Electrically assisted bicycle

Abstract

The present invention provides an electrically assisted bicycle that can suppress a metal sound and unnecessary rotation of pedals during gear change.　Provided is an electrically assisted bicycle (1) wherein the magnitude of assistance with pedals (4) is limited from when a first transmission gear ratio is changed to a second transmission gear ratio until when the assistance with the pedals (4) which corresponds to the second transmission gear ratio is started.

Description

Electrically assisted bicycles

[0001] The present invention relates to an electrically assisted bicycle.

[0002] There is a known electrically assisted bicycle that is configured to determine whether or not assistance is required based on the force applied to the pedals, and if assistance is required, to rotate the motor to provide assistance to the electrically assisted bicycle (see, for example, Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2020-90109

[0004] For example, with an electrically assisted bicycle, when shifting gears when the amount of assistance from the drive system, also known as the motor drive unit, is large, a metallic noise may be heard from the drive system, or when shifting to a lighter gear, the pedals may rotate more than necessary.

[0005] Therefore, one of the objects of the present invention is to provide an electrically assisted bicycle that can suppress the generation of metallic noise or excessive rotation of the pedals when shifting gears.

[0006] (1): In the electrically assisted bicycle of the present invention, the magnitude of pedal assist is limited from the time when the gear ratio is changed from the first to the second gear ratio until pedal assist corresponding to the second gear ratio begins.

[0007] (2): In (1), the limited magnitude of the pedal assist may be smaller than the magnitude of the pedal assist corresponding to the second gear ratio.

[0008] (3): In (1) or (2), the time from when the gear ratio is changed from the first gear ratio to the second gear ratio until when assistance for the pedal corresponding to the second gear ratio begins may be different from the time from when the gear ratio is changed from the third gear ratio to the fourth gear ratio until when assistance for the pedal corresponding to the fourth gear ratio begins.

[0009] (4): In any of (1) to (3), the time until the pedal assist corresponding to the second gear ratio starts may be within the time required for one rotation of the pedal.

[0010] (5): In any one of (1) to (4), a rotating device having a wheel, a control device, a reducer, and a motor that assists the pedal, a sensor that detects the rotation speed of the wheel, and a sensor that detects the rotation speed of the motor, wherein Nw is the rotation speed (rpm) of the wheel, Nm is the rotation speed (rpm) of the motor, and gr ＭＤＵ is the reduction ratio of the rotation device, and the control device may determine whether the magnitude of the following equation (1) is included within a predetermined range corresponding to the gear ratio. ＭＤＵ ・Nw)...Formula (1)

[0011] (6): Another electrically assisted bicycle according to the present invention is equipped with a control device, and the magnitude of the pedal assist is limited from the time the stopped control device is started until pedal assist corresponding to the gear ratio begins.

[0012] (7): In (6), the limited magnitude of the pedal assist may be smaller than the magnitude of the pedal assist corresponding to the gear ratio.

[0013] (8) In (6) or (7), the time until the pedal assist corresponding to the gear ratio starts may be within the time required for one rotation of the pedal.

[0014] (9): In any one of (6) to (8), a rotating device having a wheel, the control device, a reducer and a motor that assists the pedal, a sensor that detects the rotation speed of the wheel, and a sensor that detects the rotation speed of the motor, wherein Nw is the rotation speed (rpm) of the wheel, Nm is the rotation speed (rpm) of the motor, and gr ＭＤＵ may be the reduction ratio of the rotation device, and the control device may determine whether the magnitude of the following equation (1) is included within a predetermined range corresponding to the speed change ratio. ＭＤＵ ・Nw)...Formula (1)

[0015] 11(a) is a side view showing an example of an electrically assisted bicycle according to a first embodiment of the present invention. FIG. 11(b) is a block diagram showing the configurations of a control device, sensors, and motor provided in the electrically assisted bicycle shown in FIG. 1. FIG. 11(c) is a diagram showing an example of a table stored in a memory unit of the control device shown in FIG. 2. FIG. 11(d) is a flowchart showing an example of a flow of control by a control device provided in the electrically assisted bicycle shown in FIG. 1. FIG. 11(b) is a block diagram showing the configurations of a control device, sensors, and motor provided in an electrically assisted bicycle according to a second embodiment of the present invention. FIG. 11(c) is a block diagram showing the functional configuration of a fourth calculation unit provided in the electrically assisted bicycle shown in FIG. 5. FIG. 11(a) is a flowchart for explaining part of the control of the electrically assisted bicycle shown in FIG. 5. FIG. 11(b) is a timing diagram for explaining one control of the electrically assisted bicycle shown in FIG. 5. FIG. 11(c) is a timing diagram for explaining other control of the electrically assisted bicycle shown in FIG. 5. FIG. 11(c) is a timing diagram for explaining other control of the electrically assisted bicycle shown in FIG. 5. FIG. 11(b) is a flowchart for explaining a gear ratio state determination process in the electrically assisted bicycle shown in FIG. 5. FIG. 11(c) is a simulation diagram for explaining detection during gear shifting and motor control in the electrically assisted bicycle shown in FIG. 5. FIG. 11(a) is a simulation diagram showing an enlarged portion of FIG. 11(a) where gear G9 is changed to gear G8, and where gear G8 is confirmed after passing through the gear ratio state determination process shown in FIG. 11A is an enlarged simulation diagram of the portion of FIG. 11A in which the gear is changed from G2 to G1, and then the gear is determined to be G1 through the gear ratio state determination process shown in FIG. 10.

[0016] Below, embodiments for implementing an electrically assisted bicycle according to the present invention are illustrated with reference to the accompanying drawings. The embodiments illustrated below are intended to facilitate understanding of the present invention and are not intended to limit the present invention. The present invention can be modified or improved from the following embodiments without departing from the spirit of the present invention. Furthermore, in the accompanying drawings, the dimensions of each component may be exaggerated or reduced, and hatching may be omitted, in order to facilitate understanding.

[0017] First Embodiment FIG. 1 is a side view showing an electrically assisted bicycle according to a first embodiment. As shown in FIG. 1, the electrically assisted bicycle 1 includes a frame F, a handlebar H, a saddle S, a transmission body TC, a chain ring CR, a sprocket SP, a battery B, a motor drive unit (MDU) 100 (hereinafter referred to as "MDU 100") as a rotating device, wheels (front wheel 2 and rear wheel 3), and pedals 4. The chain ring CR is a gear that rotates together with the pedals 4 under predetermined conditions (e.g., when the driving force of the MDU 100 is transmitted to the pedals 4), and in this embodiment, includes a single gear. The sprocket SP is attached to the rear wheel 3 and is configured as a multi-stage gear with multiple gears stacked on top of each other. That is, the sprocket SP has i gear stages (i is a natural number greater than or equal to 2). The transmission body TC is stretched across the gears of the chain ring CR and the gears of the sprocket SP. The MDU 100 includes a motor 40 and a control device 50 that controls the drive of the motor 40 to provide assistance to the electrically assisted bicycle 1. When a rider sits on the saddle S of the electrically assisted bicycle 1 and rotates the pedals 4, under predetermined conditions, driving force is transmitted to a wheel (typically the rear wheel 3) via the chain ring CR, sprocket SP, and transmission body TC, enabling forward travel. At this time, under predetermined conditions, the motor 40 of the MDU 100 rotates under the control of the control device 50, and the assistance provided by the rotation of the motor 40 reduces (assists) the force exerted by the rider on the pedals 4. The transmission body TC may be a chain or a belt.

[0018] A first sensor 5 is arranged, for example, near the rotation axis of the front wheel 2 or rear wheel 3, for detecting the rotation speed Nw (rpm) of the wheel (front wheel 2 and rear wheel 3) and the vehicle speed Vb (km / h) of the electric assist bicycle 1. In this specification, "detecting the wheel rotation speed Nw (rpm) and the vehicle speed Vb (km / h) of the electrically assisted bicycle 1" may mean that the first sensor 5 itself calculates the wheel rotation speed Nw (rpm) and the vehicle speed Vb (km / h) of the electrically assisted bicycle 1, or that the first sensor 5 outputs signals necessary for calculating the wheel rotation speed Nw (rpm) and the vehicle speed Vb (km / h) of the electrically assisted bicycle 1 to the control device 50, and the control device 50 calculates the wheel rotation speed Nw (rpm) and the vehicle speed Vb (km / h) of the electrically assisted bicycle 1, or that the first sensor 5 outputs signals necessary for calculating the wheel rotation speed Nw (rpm) and the vehicle speed Vb (km / h) of the electrically assisted bicycle 1 to another calculation device (not shown), and the calculation device that receives the output signal calculates the wheel rotation speed Nw (rpm) and the vehicle speed Vb (km / h) of the electrically assisted bicycle 1 and outputs them to the control device 50. FIG. 1 shows an example in which the first sensor 5 is disposed near the rotation axis of the rear wheel 3. The first sensor 5 may be a known sensor capable of detecting the wheel rotation speed Nw (rpm) and the vehicle speed Vb (km / h) of the power-assisted bicycle 1, or a known sensor capable of outputting signals necessary to calculate the wheel rotation speed Nw (rpm) and the vehicle speed Vb (km / h) of the power-assisted bicycle 1. The first sensor 5 may be, for example, a magnetic sensor or a Hall sensor capable of detecting the wheel rotation speed Nw (rpm) and the vehicle speed Vb (km / h) of the power-assisted bicycle 1, or an optical sensor capable of detecting the wheel rotation speed Nw (rpm) and the vehicle speed Vb (km / h) of the power-assisted bicycle 1. The first sensor 5 may be disposed at any position where it can detect the wheel rotation speed Nw (rpm) and the vehicle speed Vb (km / h) of the power-assisted bicycle 1, and may be disposed, for example, at a position away from the rotation axis of the front wheel 2 or the rear wheel 3.

[0019] Further, a fourth sensor 8 for detecting a predetermined rotation angle An (deg) of the wheel is disposed near the rotation axis of the front wheel 2 or the rear wheel 3. In this specification, "detecting the predetermined rotation angle An (deg) of the wheel" may mean that the fourth sensor 8 itself calculates the predetermined rotation angle An (deg), that the fourth sensor 8 outputs a signal required to calculate the predetermined rotation angle An (deg) of the wheel to the control device 50, and the control device 50 calculates the predetermined rotation angle An (deg), or that the fourth sensor 8 outputs a signal required to calculate the predetermined rotation angle An (deg) of the wheel to another calculation device (not shown), and the calculation device that receives the output signal calculates the predetermined rotation angle An (deg) of the wheel and outputs it to the control device 50. FIG. 1 shows an example in which the fourth sensor 8 is disposed near the rotation axis of the rear wheel 3. The fourth sensor 8 may be a known sensor capable of detecting the predetermined rotation angle An (deg) of the wheel or capable of outputting a signal necessary to calculate the predetermined rotation angle An (deg). The fourth sensor 8 may be, for example, a magnetic sensor or a Hall sensor capable of detecting the predetermined rotation angle An (deg), or an optical sensor capable of detecting the predetermined rotation angle An (deg). The fourth sensor 8 may be located at any position where it can detect the predetermined rotation angle An (deg), and may be located, for example, at a position away from the rotation axis of the front wheel 2 or the rear wheel 3.

[0020] In this embodiment, the fourth sensor 8 outputs a signal Sa to the control device 50 (specifically, the third calculation unit 53, which will be described later) every time a wheel (e.g., the rear wheel 3) rotates a predetermined rotation angle An (deg). That is, the fourth sensor 8 outputs a signal Sa indicating that the wheel has rotated the predetermined rotation angle An (deg) to the control device 50. The predetermined rotation angle An (deg) is not particularly limited, and may be, for example, 30°, 120°, 90°, 60°, 45°, 15°, 10°, or any predetermined angle selected within the range of 1° to 360°.

[0021] The fourth sensor 8 and the first sensor 5 may be a common sensor.

[0022] The MDU 100 and battery B are typically arranged around the crankshaft 23 connected to the pedals 4. As shown in FIG. 1 , the MDU 100 includes a rotation device 70, a control device 50, and a housing 60. The housing 60 is fixed to, for example, the frame F of the electrically assisted bicycle 1 and houses the rotation device 70, control device 50, and other components inside. The rotation device 70 includes a motor 40, a speed reducer 10, and a third sensor 7 serving as a torque sensor. In FIG. 1 , the rotation device 70 and control device 50 are shown with dashed lines because they are housed within the housing 60 and cannot be seen. The control device 50 may be located partially or entirely outside the housing 60. The battery B supplies power to the motor 40 and control device 50, which operate using this power.

[0023] The motor 40 of the rotation device 70 is driven under the control of the control device 50 and assists the rotation of the pedal 4 via the reducer 10. In this specification, "rotation of the pedal 4" refers to the rotation (revolution) of the pedal 4 around the crankshaft 23. In this specification, "assist" also includes reducing the force (depression force) required to manually rotate the pedal 4 (push the pedal 4). The motor 40 is not particularly limited, and may be, for example, a brushless DC motor having coils corresponding to three phases (U phase, V phase, and W phase).

[0024] 1 , a second sensor 6 is disposed in the motor 40 to detect the rotation speed Nm (rpm) of the rotor of the motor 40 (hereinafter simply referred to as “rotation speed Nm (rpm) of the motor 40”). In this specification, “detecting the rotation speed Nm (rpm) of the motor 40” may mean that the second sensor 6 itself calculates the rotation speed Nm (rpm) of the motor 40, or that the second sensor 6 outputs a signal required to calculate the rotation speed Nm (rpm) of the motor 40 to the control device 50, and the control device 50 calculates the rotation speed Nm (rpm) of the motor 40, or that the second sensor 6 outputs a signal required to calculate the rotation speed Nm (rpm) of the motor 40 to another computing device (not shown), and the computing device that receives the output signal calculates the rotation speed Nm (rpm) of the motor 40 and outputs the calculated value to the control device 50. 1 shows an example in which the second sensor 6 is mounted on the motor 40, the location of the second sensor 6 is not particularly limited as long as it is a location where the rotation speed Nm (rpm) of the motor 40 can be detected. As the second sensor 6, a known sensor capable of detecting the rotation speed Nm (rpm) of the motor 40 or capable of outputting a signal necessary to calculate the rotation speed Nm (rpm) of the motor 40 can be used. The second sensor 6 may be, for example, a magnetic sensor or a Hall sensor capable of detecting the rotation speed Nm (rpm) of the motor 40, or an optical sensor capable of detecting the rotation speed Nm (rpm) of the motor 40.

[0025] The second sensor 6 does not have to be a sensor that detects the rotation speed Nm (rpm) of the motor 40. The second sensor 6 may be, for example, a sensor that can directly calculate the rotation speed Nc (rpm) of the chain ring CR. For example, by attaching a magnet to the chain ring CR and attaching a magnetic sensor near the chain ring CR, it is possible to directly detect the rotation speed Nc (rpm) of the chain ring CR.

[0026] As shown in FIG. 1 , the crankshaft 23 passes through the housing 60 of the MDU 100. Pedals 4 are fixed to one end and the other end of the crankshaft 23 in the extending direction (axial or longitudinal direction). The crankshaft 23 rotates as the pedal 4 is pedaled. The third sensor 7 may detect the pedal force Tf (N) applied to the pedal 4 by detecting strain on the crankshaft 23 that is deformed due to the pedal force applied to the pedal 4. The control device 50 controls the driving of the motor 40 based on the detected pedal force, etc.

[0027] In this specification, "detecting the pedaling force Tf(N) applied to the pedal 4" may mean that the third sensor 7 itself calculates the pedaling force Tf(N), or that the third sensor 7 outputs a signal necessary to calculate the pedaling force Tf(N) to the control device 50, and the control device 50 calculates the pedaling force Tf(N), or that the third sensor 7 outputs a signal necessary to calculate the pedaling force Tf(N) to another arithmetic device (not shown), and the arithmetic device that receives the signal calculates the pedaling force Tf(N) and outputs it to the control device 50. Furthermore, the third sensor 7 may be disposed on the pedal 4, on a crank arm connecting the pedal 4 and the crankshaft 23, on the housing 60 of the MDU 100, or at any other location. In the electrically assisted bicycle 1, the output of the motor 40 is adjusted according to the pedaling force Tf(N) detected by the third sensor 7, etc.

[0028] The reducer 10 of the rotating device 70 includes a plurality of gears, a plurality of shafts, a plurality of clutches (one-way clutches), etc. With this configuration, the reducer 10 has a predetermined reduction ratio gr ＭＤＵ and this reduction ratio gr ＭＤＵThe rotation of the motor 40 can be reduced based on the above. A chain ring CR is fixed to one of the multiple gears in the reducer 10. The multiple clutches of the reducer 10 include a gear (hereinafter referred to as the "output gear") fixed to the chain ring. The multiple clutches of the reducer 10 are configured to transmit rotation in one direction (forward direction) of the pedals 4 (crankshaft 23) and not transmit rotation in the other direction (reverse direction).

[0029] For example, when the pedals 4 are rotated in the reverse direction (the direction opposite to the direction in which the pedals 4 are rotated to move the electrically assisted bicycle 1 forward), the crankshaft 23 rotates in the reverse direction relative to the output gear. In this case, the rotation of the pedals 4 (crankshaft 23) is not transmitted to the output gear. That is, in this case, the rotation of the pedals 4 (crankshaft 23) is not transmitted to the chain ring CR fixed to the output gear, so the wheel is prevented from rotating in response to pedaling of the pedals 4, and the rider's pedaling force (treading force) is prevented from becoming a propulsion force for the electrically assisted bicycle 1. In this way, when the pedals 4 (crankshaft 23) rotate in the relative reverse direction, the clutch (one-way clutch) of the reducer 10 or the like prevents the assist of the motor 40 from being transmitted to the pedals 4. Note that hereinafter, "relative reverse rotation" may be simply referred to as "reverse rotation."

[0030] On the other hand, when the rotation speed of the pedal 4 (crankshaft 23) in the forward direction reaches a certain rotation speed, the crankshaft 23 and the output gear are connected by a clutch, and the crankshaft 23 and the output gear rotate synchronously as a unit (hereinafter, this may be referred to as "synchronous rotation in the forward direction"). In this way, the rotation of the pedal 4 (crankshaft 23) is transmitted to the output gear. This in turn rotates the chain ring CR fixed to the output gear, and driving force is transmitted to the rear wheel 3 via the transmission body TC that is stretched between the gear of the chain ring CR and the gear of the sprocket SP. In other words, when the rotation speed of the pedal 4 (crankshaft 23) in the forward direction reaches a certain rotation speed, the clutch of the reducer 10 or the like enables the rotational force of the motor 40 to be transmitted to the pedal 4, and the force required to press the pedal 4 is reduced (assisted) under predetermined conditions.

[0031] As shown in FIG. 1 , a clutch RC is provided on the rotation shaft of the rear wheel 3. This clutch RC may be a one-way clutch such as a ratchet. The clutch RC is configured to transmit the rotation of the sprocket SP rotating in a forward direction relative to the rotation direction of the rear wheel 3 to the rear wheel 3, but not to transmit the rotation of the sprocket SP rotating in a reverse direction relative to the rotation direction of the rear wheel 3 to the rear wheel 3. As a result, when the wheel rotation speed Nw (rpm) increases due to driving downhill, the clutch RC disengages, preventing the pedals 4 from rotating rapidly in response to the fast rotation of the wheel. Therefore, when the rotation of the sprocket SP rotating in the forward direction relative to the rotation direction of the rear wheel 3 is transmitted to the rear wheel 3, the metal members constituting the clutch RC of the rear wheel 3 come into contact with each other. As a result, the rotational force of the pedals 4 and the rotational force of the motor 40 are transmitted to the rear wheel 3 via the chain ring CR, the sprocket SP, the transmission body TC, and the clutch RC of the rear wheel 3.

[0032] Next, the control device 50 will be described in detail. FIG. 2 is a block diagram showing the configuration of the control device 50, the first sensor 5, the second sensor 6, the third sensor 7, the fourth sensor 8, and the motor 40. As shown in FIG. 2, the control device 50 includes a control circuit 50a and a drive circuit 50b. Note that the functions and configuration of the control device 50 shown in FIG. 2 may be part of the overall functions and configuration of the control device 50. In other words, the control device 50 may include functions or configurations other than those shown in FIG. 2.

[0033] The control circuit 50a is realized by a program processing device (e.g., a microcontroller) having a configuration in which a processor such as a CPU, various storage devices such as RAM and ROM, and peripheral circuits such as a counter (timer), an A / D conversion circuit, a D / A conversion circuit, a clock generation circuit, and an input / output I / F circuit are connected to each other via a bus or dedicated lines.

[0034] 2 , in this embodiment, the control circuit 50 a includes, as functional blocks, a first calculation unit 51, a second calculation unit 52, a third calculation unit 53, a fourth calculation unit 54, a determination unit 56, a mode determination unit 57, a storage unit (memory) 58, a drive signal generation unit 59, and an output suppression unit 80. The storage unit 58 may be all or part of the above-mentioned storage devices such as RAM and ROM. The first calculation unit 51, the second calculation unit 52, the third calculation unit 53, the fourth calculation unit 54, the determination unit 56, the mode determination unit 57, the drive signal generation unit 59, and the output suppression unit 80 are realized, for example, by a processor in a program processing device serving as the control circuit 50 a executing various arithmetic operations in accordance with various programs stored in the above-mentioned storage devices, including the storage unit 58, and controlling peripheral circuits such as a counter and an A / D conversion circuit. In this embodiment, the various programs described above include a program (hereinafter sometimes referred to as the "stage determination program") that determines the current gear stage of the sprocket SP (hereinafter sometimes referred to as the "current stage") based on the rotation speed Nc (rpm) of the chain ring CR and the rotation speed Nw (rpm) of the wheel.

[0035] In addition, when the second sensor 6 is, for example, a Hall sensor or the like that detects the rotation speed Nm (rpm) of the motor 40, the gear determination program calculates the reduction ratio gr of the reducer 10 in the rotation speed Nm (rpm) of the motor 40. ＭＤＵ and then determine the current gear position based on the calculated rotation speed Nc (rpm) of the chainring CR and the rotation speed Nw (rpm) of the wheel. Also, if the second sensor 6 is a sensor that directly detects the rotation speed of the chainring CR, the gear position determination program may determine the current gear position based on the rotation speed Nc (rpm) of the chainring CR detected by the second sensor 6 and the rotation speed Nw (rpm) of the wheel.

[0036] In this embodiment, the storage unit 58 stores, in addition to the above-mentioned program, the reduction ratio gr of the reducer 10. ＭＤＵ (hereinafter, sometimes referred to as "reduction ratio data"), a table T of the gear ratio Gr of the electrically assisted bicycle 1, data indicating the current gear, and data indicating the previous current gear, etc. The control circuit 50a may also have other functional blocks.

[0037] Here, the table T of the gear ratio Gr will be explained. Fig. 3 shows an example of the table T. As described above, in this embodiment, the chain ring CR includes one gear stage, and the sprocket SP has i gear stages (i is a natural number of 2 or more). Therefore, the number of teeth n of the chain ring CR is ｃ is a constant, and the number of teeth of the sprocket SP is n ｓ ｉ differs depending on the gear stage (stage 1 to stage i) of the sprocket SP. Here, when the sprocket SP is stage 1, the number of teeth of the sprocket SP is n ｓ １ When the sprocket SP has two stages, the number of teeth of the sprocket SP is n ｓ ２ When the sprocket SP has three stages, the number of teeth of the sprocket SP is n ｓ ３ When the sprocket SP has i stages, the number of teeth of the sprocket SP is expressed as n ｓ ｉIn this embodiment, the gear ratio Gr of the power-assisted bicycle 1 is defined by the following equation (A): Gr=n ｓ ｉ / n ｃ As shown in FIG. 3, in table T, data on the gear ratio Gr based on equation (A) is associated with each of the gear stages (stage 1 to stage i) of the sprocket SP.

[0038] 2, signals output from the first sensor 5 that detects the rotation speed Nw of the wheel and the vehicle speed Vb of the electrically assisted bicycle 1, the second sensor 6 that detects the rotation speed Nm of the rotor of the motor 40, the third sensor 7 that serves as the torque sensor, and the fourth sensor 8 that detects the predetermined rotation angle An of the wheel are input to the control circuit 50a. The first calculation unit 51 calculates the rotation speed Nw (rpm) of the wheel based on the signal input from the first sensor 5. The second calculation unit 52 calculates the rotation speed Nm (rpm) of the motor 40 based on the signal input from the second sensor 6.

[0039] When the signal Sa is input to the third calculation unit 53 from the fourth sensor 8, the third calculation unit 53 calculates the number of rotations Nw (rpm) of the wheel calculated by the first calculation unit 51, the number of rotations Nm (rpm) of the motor 40 calculated by the second calculation unit 52, and the reduction ratio data (reduction ratio gr of the reducer 10) stored in the memory unit 58. ＭＤＵ Based on the data of the rotation speed Nc (rpm) of the chain ring CR and the rotation speed Nw (rpm) of the wheel (for example, the rear wheel 3), a ratio R (Nc / Nw) of the rotation speed Nc (rpm) of the chain ring CR is calculated. Here, the rotation speed Nc (rpm) of the chain ring CR is calculated by multiplying the rotation speed Nm (rpm) of the motor 40 by the reduction ratio gr of the reducer 10. ＭＤＵ Therefore, the third calculation unit 53 calculates the ratio R(Nc / Nw) based on the following formula (1): R=Nm / (gr ＭＤＵ ・Nw)...Formula (1)

[0040] In this embodiment, the ratio R can also be calculated by detecting the rotation speed Nc (rpm) of the chain ring CR using a sensor that directly detects the rotation speed Nc (rpm) of the chain ring CR. That is, when the rotation speed Nc (rpm) of the chain ring CR is detected using a sensor that directly detects the rotation speed Nc (rpm) of the chain ring CR, the third calculation unit 53 may calculate the ratio R using the following equation (2): R=Nc / Nm (2)

[0041] However, a sensor (typically a Hall sensor) detecting the rotational speed Nm (rpm) of the motor 40 may be able to detect the rotation angle more accurately than a sensor directly detecting the rotational speed of the pedals (crankshaft). Therefore, by calculating the ratio R using Equation (1), it is possible to obtain data on the ratio R with greater accuracy (e.g., at a time interval desired for use in software). A first case in which a sensor detecting the rotational speed Nm (rpm) of the motor 40 can obtain the rotational speed more accurately is when, in the case of a sensor directly detecting the rotational speed of the pedals, the distance between the magnet on the shaft connecting the two pedals 4 and the magnetic sensor changes slightly due to distortion of the shaft caused by pedal force. On the other hand, the sensor detecting the rotational speed Nm (rpm) of the motor 40 is fixed so that it is always in the same position relative to the rotor of the motor 40. Therefore, the sensor detecting the rotational speed Nm (rpm) of the motor 40 can obtain accurate magnetic information virtually all the time. A second case is when the rotational speed is affected by the power of the rotating body being detected. That is, in a sensor that detects the rotation speed Nm (rpm) of the motor 40, the power of the motor 40, which is the rotating body to be detected, is electricity, whereas in a sensor that directly detects the rotation speed of the pedals, the power of the rotating body to be detected is human power. For example, if the detection cycle is set to 1 ms, the fluctuation per detection cycle will be smaller with electricity than with human power, and this can be used as data in the software.

[0042] The fourth calculation unit 54 calculates the pedal force Tf (N) applied to the pedal 4 based on the signal input from the third sensor 7, and further calculates a torque command value Tm (Nm), which is a target value for causing the motor 40 to exert a predetermined torque, based on the wheel rotation speed Nw (rpm) and vehicle speed Vb (km / h) calculated by the first calculation unit 51.

[0043] The storage unit 58 stores "data indicating the current row" and "data indicating the previous current row."

[0044] The determination unit 56 determines the current stage using a stage determination program based on the ratio R calculated by the third calculation unit 53, and stores data indicating the determined current stage in the storage unit 58. Specifically, the determination unit 56 stores the data indicating the most recently determined current stage in the storage unit 58 as "data indicating the current stage." Accordingly, the determination unit 56 shifts (updates) the data that was previously stored in the storage unit 58 as "data indicating the current stage" to "data indicating the previous current stage," and erases the data that was previously stored in the storage unit 58 as "data indicating the previous current stage."

[0045] The determination unit 56 also reads the table T and the "data indicating the previous current gear" from the storage unit 58 and determines whether the ratio R calculated by the third calculation unit 53 is within a range of ±X% of the value of the gear ratio Gr of the previous current gear. In other words, it determines whether the current gear has been changed from the previous current gear. The value of X may be individually and specifically set based on the performance of the electrically power-assisted bicycle (e.g., motor output, reduction ratio of the reducer, wheel diameter, etc.), and may be 10 (i.e., ±10%), 5 (i.e., ±5%), 15 (i.e., ±15%), or some other value. If the determination unit 56 determines that the ratio R is within a range of ±X% of the value of the gear ratio Gr of the previous current gear, it outputs a first signal S1 to the mode determination unit 57. If the determination unit 56 determines that the ratio R is not within a range of ±X% of the value of the gear ratio Gr of the previous current gear, it outputs a second signal S2 to the mode determination unit 57.

[0046] The mode determination unit 57 includes a counter 57C. This counter 57C is configured to output a third signal S3 to the output suppression unit 80 when the first signal S1 is input from the determination unit 56 to the counter 57C N or more consecutive times, where N is a natural number greater than or equal to 1. That is, the mode determination unit 57 (counter 57C) outputs the third signal S3 to the output suppression unit 80 when the first signal S1 is input N consecutive times, and also outputs the third signal S3 to the output suppression unit 80 when the first signal S1 is input (N+1), (N+2), ..., (N+n (n is a natural number greater than or equal to 1)) consecutive times. This third signal S3 indicates the current gear of the sprocket SP. That is, the third signal S3 is output when it is determined that the ratio R is within ±X% of the value of the gear ratio Gr of the current gear. On the other hand, when the first signal S1 is not input to the mode determination unit 57 consecutively N times or more, in other words, when the second signal S2 is input to the mode determination unit 57, the mode determination unit 57 outputs the fourth signal S4 to the output suppression unit 80. Note that, as will be mentioned again later, the mode determination unit 57 may reset the value of the counter 57C to zero when it outputs the fourth signal S4, or may return the value of the counter 57C to N when the value of n reaches a predetermined value.

[0047] When the third signal S3 is input from the mode determination unit 57, the output suppression unit 80 outputs a fifth signal S5 indicating the torque command value Tm (Nm) calculated by the third calculation unit 53 to the drive signal generation unit 59. The control mode in which the motor 40 is driven based on the torque command value Tm (Nm) is the normal output mode. On the other hand, when the fourth signal S4 is input from the mode determination unit 57, the output suppression unit 80 outputs a sixth signal S6 indicating a torque command value (hereinafter, sometimes referred to as a "reduced torque command value RTm (Nm)") obtained by suppressing the torque command value Tm (Nm) calculated by the third calculation unit 53 to the drive signal generation unit 59. The control mode in which the motor 40 is driven based on the reduced torque command value RTm (Nm) is the output reduced mode.

[0048] Here, the suppression torque command value RTm (Nm) for the output suppression mode is smaller than the torque command value Tm (Nm) for the normal output mode, and may be, for example, the torque obtained by multiplying the smallest torque (Nm) of motor 40 in the normal output mode by a number M (0<M<1) that is smaller than 1. In other words, in the electrically assisted bicycle 1, the suppression torque command value RTm (Nm) of motor 40 when ratio R is outside the range of ±X% of a certain gear ratio Gr is smaller than the torque command value Tm (Nm) of motor 40 when ratio R is within a predetermined range Ra each time the first signal S1 is input N or more consecutive times.

[0049] The drive signal generation unit 59 generates a drive signal Sd for driving the motor 40 and outputs it to the drive circuit 50b. Specifically, when the fifth signal S5 is input, the drive signal generation unit 59 outputs a drive signal Sd for causing the motor 40 to exert a torque of the torque command value Tm (Nm) indicated by the fifth signal S5 to the drive circuit 50b, and when the sixth signal S6 is input, the drive signal generation unit 59 outputs a drive signal Sd for causing the motor 40 to exert a torque of the suppression torque command value RTm (Nm) indicated by the sixth signal S6 to the drive circuit 50b. The drive signal Sd is, for example, a PWM (Pulse Width Modulation) signal.

[0050] For example, if the motor 40 is a brushless DC motor having coils corresponding to three phases (U phase, V phase, and W phase), the drive circuit 50b drives the motor 40 by exciting the coils corresponding to the three phases (U phase, V phase, and W phase) of the motor 40 based on the drive signal Sd. The drive circuit 50b may include, for example, an inverter circuit that drives each coil, a pre-drive circuit that drives the inverter circuit in response to the drive signal, and a current detection circuit that detects the current flowing through each coil.

[0051] The control device 50 as described above may be configured such that part or all of the control circuit 50a and part or all of the drive circuit 50b are packaged as a single integrated circuit device (IC), or such that the control circuit 50a and the drive circuit 50b are each packaged as separate integrated circuit devices.

[0052] Next, an example of steps in the control by the control device 50 will be described. FIG. 4 is a flowchart showing an example of steps in the control by the control device 50. Note that the steps in the control by the control device 50 are not limited to the steps in the control shown in FIG. 4. As shown in FIG. 4, the steps in the control according to this embodiment include steps St1 to St9. Hereinafter, among the steps in the control shown in FIG. 4, steps St2 to St9 may be referred to as a "mode determination flow MF."

[0053] In this embodiment, for example, the step of starting control may be started (START) when the drive of the motor 40 starts. Specifically, the step of starting control may be started when the drive signal generating unit 59 generates the drive signal Sd for driving the motor 40 and outputs it to the drive circuit 50b. At this time, the gear position of the sprocket SP that was set immediately before the step of control started (START) is stored in the memory unit 58 as "data indicating the current gear position." Note that at the time of START, the "data indicating the previous current gear position" does not have to be stored in the memory unit 58.

[0054] (Step St1) When a signal Sa indicating that the wheel has rotated a predetermined rotation angle An (deg) is input to the third calculation unit 53, the control device 50 advances the control step to step St2 and starts the mode determination flow MF. On the other hand, when the signal Sa is not input to the third calculation unit 53, the control device 50 repeats this step. Note that the signal Sa does not have to be a signal indicating that the wheel has rotated a predetermined rotation angle An (deg), and may be, for example, a signal transmitted at regular intervals from a predetermined timer.

[0055] (Step St2) When the signal Sa is input from the fourth sensor 8 to the third calculation unit 53, the control device 50 calculates the ratio R in the third calculation unit 53 based on the above-mentioned formula (1). Specifically, the third calculation unit 53 calculates the ratio R based on the number of rotations Nw (rpm) of the wheel calculated by the first calculation unit 51, the number of rotations Nm (rpm) of the motor 40 calculated by the second calculation unit 52, and the reduction ratio data (reduction ratio gr of the reducer 10) stored in the memory unit 58. ＭＤＵ ) and calculates the ratio R. When the third calculation unit 53 calculates the ratio R, the control device 50 outputs a signal indicating the ratio R to the determination unit 56, and the control proceeds to step St3. Note that in this step, the ratio R may be calculated based on equation (2).

[0056] (Step St3) The control device 50 executes this step when a signal indicating the ratio R is input from the third calculation unit 53. Specifically, the control device 50 determines the current stage based on the ratio R calculated by the third calculation unit 53 and the stage determination program described above. The determination unit 56 stores data indicating the determined current stage in the memory unit 58 as "data indicating the current stage." Accordingly, the determination unit 56 transitions (updates) the data that was previously stored in the memory unit 58 as "data indicating the current stage" to "data indicating the previous current stage."

[0057] For example, consider a case where the mode decision flow MF currently being executed is the (m+1)th mode decision flow MF (m is a natural number) and the power-assisted bicycle 1 has not shifted gears (in this embodiment, the gear position of the sprocket SP has not changed). In this case, in this step of the (m+1)th mode decision flow MF and in this step of the previous mth mode decision flow MF, the "current gear position" is determined to be, for example, gear position i. In other words, by going through this step in the (m+1)th mode decision flow MF, data indicating gear position i is stored in the memory unit 58 as both "data indicating the previous current gear position" and "data indicating the current gear position."

[0058] On the other hand, consider a case where the mode decision flow MF currently being executed is the (m+1)th mode decision flow MF, and the power-assisted bicycle 1 has shifted gears (in this embodiment, the gear position of the sprocket SP has been changed). For example, if the (i-1)th gear was determined in the mth mode decision flow MF, and if this step of the (m+1)th mode decision flow MF determines that the ith gear is being selected, the control device 50 overwrites (updates) the data indicative of the ith gear as the "data indicative of the current gear" in the storage unit 58, and accordingly overwrites (updates) the data indicative of the (i-1)th gear as the "data indicative of the previous current gear" in the storage unit 58.

[0059] Then, the control device 50 advances the control to step St4.

[0060] (Step St4) The control device 50 reads out "data indicating the previous current gear" and table T from the storage unit 58, and determines in the determination unit 56 whether the ratio R calculated in step St2 is within a range of ±X% of the value of the gear ratio Gr of the previous current gear that was updated in step St3. That is, the control device 50 determines whether the ratio R (magnitude) calculated using equation (1) or equation (2) is within a predetermined range corresponding to the gear ratio Gr of the previous current gear. The control device 50 determines in the determination unit 56 whether the ratio R is within the value of the gear ratio Gr of the previous current gear (for example, the value of the gear ratio Gr of the i-th gear). ｓ ｉ / nc), the control proceeds to step St5. Specifically, the determination unit 56 outputs the second signal S2 to the mode determination unit 57, which causes the control to proceed to step St5. For example, if the (i-1)th gear was determined in step St2 of the previous mode determination flow MF and the electrically assisted bicycle 1 was shifted to the ith gear during the currently executed mode determination flow MF, the ratio R calculated in step St2 of the currently executed mode determination flow MF (the ratio R calculated based on the ith gear) is calculated based on the "gear ratio of the previous current gear (n ｓ ｉ-１It is assumed that the value is not included in the range of ±X% of the value of (1 / nc).

[0061] On the other hand, when the determination unit 56 of the control device 50 determines that the ratio R is within the range of ±X% of the value of the gear ratio Gr of the current gear of the previous stage, the control proceeds to step St6. For example, if the i-stage was determined in the previous mode determination flow MF and the i-stage is also determined in step St3 of the currently executed mode determination flow MF, the ratio R calculated in step St2 of the currently executed mode determination flow MF (the ratio R calculated based on the i-stage) is the gear ratio n of the current gear of the previous stage calculated based on the gear (i-stage) determined in step St3 of the previous mode determination flow MF. ｓ ｉ / nc" and "the gear ratio n of the current gear" calculated based on the gear (i-th gear) determined in step St3 of the current mode determination flow MF. ｓ ｉ It is assumed that the value is within the range of ±X% of " / nc".

[0062] (Step St5) In this step, the control device 50 outputs the fourth signal S4 from the mode determination unit 57 to the output suppression unit 80. Note that, when the control device 50 outputs the fourth signal S4, if the value of the counter 57C of the mode determination unit 57 is greater than zero, the control device 50 may reset the value of the counter 57C to zero. When the fourth signal S4 is input to the output suppression unit 80, the control device 50 inputs a signal S6 indicating a suppression torque command value RTm (Nm) obtained by suppressing the torque command value Tm (Nm) calculated by the third calculation unit 53 to the drive signal generation unit 59. The control device 50 generates a drive signal Sd based on the suppression torque command value RTm (Nm) in the drive signal generation unit 59 and outputs this drive signal Sd to the drive circuit 50b. The control device 50 then controls the operation of the motor 40 based on the drive signal Sd of the suppression torque command value RTm (Nm) via the drive circuit 50b. In this way, the control device 50 turns on the output suppression mode. That is, by going through this step, the motor 40 rotates with a torque smaller than in the normal output mode, and as a result, the assist by the motor 40 is reduced compared to the normal output mode. Then, the control device 50 returns the step in the control to step St1.

[0063] (Step St6) The control device 50 causes the determination unit 56 to output a first signal S1 to the mode determination unit 57. This first signal S1 is input to the counter 57C of the mode determination unit 57. That is, in this step, the control device 50 causes the determination unit 56 to output the first signal S1, which is a counter input signal, to the mode determination unit 57. Then, the control device 50 advances the control step to step St7.

[0064] (Steps St7 and St8) In step St7, the control device 50 increments the counter 57C of the mode determination unit 57 by 1 and determines whether the first signal S1 has been input to the counter 57C N or more consecutive times. Note that "consecutive inputs to the counter 57C" refers to a case where, when the currently executed mode determination flow MF is the (m+1)th mode determination flow MF, the first signal S1 has also been input to the counter 57C in step St7 of the mth mode determination flow MF. This point will be described further below.

[0065] In step St7 of the mth mode determination flow MF, if the first signal S1 has not been input to the counter 57C N or more consecutive times, the control device 50 proceeds to step St8. In step St8, the control device 50 turns on the output reduction mode, as in step St5. This causes the motor 40 to rotate with a torque smaller than in the normal output mode, resulting in reduced assistance by the motor 40 compared to the normal output mode. The control device 50 then returns the control to step St1. In step St1 to which the control device 50 has returned, if the signal Sa is input to the determination unit 56, the control device 50 executes the (m+1)th mode determination flow MF. Conversely, if the signal Sa is not input to the determination unit 56, the control device 50 does not execute the (m+1)th mode determination flow MF, and repeats step St1 until the signal Sa is input to the determination unit 56.

[0066] If the ratio R calculated in step St2 of the (m+1)th mode determination flow MF is not within ±X % of the value of the gear ratio Gr of the previous current gear (i.e., the current gear calculated in the mth mode determination flow MF), the control device 50 proceeds to step St5 in the control. That is, if the output reduction mode is selected in the mth mode determination flow MF, the control device 50 maintains the output reduction mode based on step St7 of the (m+1)th mode determination flow MF, and if the normal output mode is selected in the mth mode determination flow MF, the control device 50 switches to the output reduction mode based on step St7 of the (m+1)th mode determination flow MF. If the normal output mode was selected in the mth mode decision flow MF, the (m+1)th mode decision flow MF switches to the reduced output mode, and then step St7 is reached in the (m+2)th mode decision flow MF, the input of the first signal S1 to the counter 57C in step St7 of the (m+2)th mode decision flow MF does not result in a continuous input of the first signal S1 to the counter 57C. In this case, the control device 50 resets the value of the counter 57C to zero and returns the control to step St1.

[0067] On the other hand, if the counter 57C reaches step St7 in the mth mode decision flow MF and the first signal S1 has not been input to the counter 57C N or more consecutive times in the mth mode decision flow MF, and if the counter 57C reaches step St7 in the (m+1)th mode decision flow MF, the counter 57C is further incremented (incremented) by 1. Consider, for example, the case where m is 1 (i.e., the first mode decision flow MF). When the counter 57C reaches step St7 in the first (mth) mode decision flow MF, the counter 57C is incremented by 1, and the value of the counter 57C becomes 1. Next, when the counter 57C reaches step St7 in the second ((m+1)th) mode decision flow MF, the counter 57C is incremented (incremented) by 1, and the value of the counter 57C becomes 2. If N is 4, for example, the value of the counter 57C in the second ((m+1)th) mode decision flow MF is 2, which is smaller than 4. That is, in this case, the first signal S1 has not been input to the counter 57C four or more times (N times) in succession in the second ((m+1)th) mode decision flow MF. Therefore, the control device 50 returns to step St1 via steps St7 and St8 of the second ((m+1)th) mode decision flow MF, and executes the third ((m+2)th) mode decision flow MF. Then, when step St7 is reached in both the third and fourth ((m+3)th) mode decision flow MF, the value of the counter 57C is incremented to 4, thereby satisfying the condition of N or more times. Therefore, in this case, the control device 50 advances the control to step St9.

[0068] (Step St9) In this step, the control device 50 outputs the third signal S3 from the counter 57C to the output suppression unit 80. Then, the control device 50 outputs the fifth signal S5 indicating the torque command value Tm (Nm) from the output suppression unit 80 to the drive signal generation unit 59. Thus, in this step, the normal output mode is turned ON. Then, the control device 50 returns the control step to step St1.

[0069] In the subsequent cycle of steps in the control, when step St7 is reached consecutively, the value of counter 57C is sequentially accumulated, and the value of counter 57C increases. To prevent this, an upper limit may be set for the value of counter 57C, and when the value of counter 57C reaches the upper limit in step St7 of a step in a certain control, the value of counter 57C may be reset to N.

[0070] 4, the control device 50 of the electrically assisted bicycle 1 determines that the current gear ratio has been reached when the first signal S1 (counter input signal) is received N or more times in succession, and executes the normal output mode corresponding to the current gear. On the other hand, when the ratio R is outside the range of ±X% of the value of the gear ratio Gr of the previous current gear, the electrically assisted bicycle 1 reduces the magnitude of assistance for the rotation of the pedals 4 (torque (Nm) of the motor 40) relative to the torque Nm (rpm) of the motor 40 in the normal output mode.

[0071] As described above, if the gear was determined to be (i-1) in step St3 of the previous mode determination flow MF and the power-assisted bicycle 1 was shifted to gear i during the currently executed mode determination flow MF, the ratio R calculated in step St2 of the currently executed mode determination flow MF is the gear ratio n of the previous current gear calculated based on the gear determined in step St3 of the previous mode determination flow MF. ｓ ｉ-１ / nc". That is, when the ratio R is not within "a range of ±X% of the value of the gear ratio Gr of the current gear immediately before," it can be assumed that this is the timing when the power-assisted bicycle 1 shifted gears; specifically, in this embodiment, it is the timing when the gear of the sprocket SP was changed from the first gear ratio to the second gear ratio. As described above, when the ratio R is "outside a range of ±X% of the value of the gear ratio Gr of the current gear immediately before," the power-assisted bicycle 1 of this embodiment reduces the magnitude of assistance for the rotation of the pedal 4 (torque (Nm) of the motor 40) relative to the torque (Nm) of the motor 40 in the normal output mode. That is, according to the power-assisted bicycle 1, the magnitude of assistance for the pedal 4 is limited from the time when the gear ratio is changed from the first gear ratio (gear ratio of the current gear immediately before) to the second gear ratio (gear ratio of the current gear) until assistance for the pedal 4 corresponding to the second gear ratio begins. Furthermore, with the electrically assisted bicycle 1, the magnitude of the limited pedal 4 assist (the magnitude of assist in the output reduction mode) is smaller than the magnitude of pedal 4 assist corresponding to the second gear ratio (the magnitude of assist in the normal output mode). With this configuration, the assist from the motor 40 is limited when the electrically assisted bicycle 1 is shifted (in this embodiment, when the gear of the sprocket SP is changed), thereby making it possible to suppress metallic noises and excessive pedal rotation when shifting gears.

[0072] Furthermore, with the electrically assisted bicycle 1, gear shifts are detected based on the control described above, so there is no need to provide a separate sensor for detecting gear shifts. This makes it possible to suppress metallic noises and excessive pedal rotation when shifting gears without increasing the number of parts or costs.

[0073] As described above, the control device 50 according to this embodiment determines that the gear ratio has been reached for the current gear when the first signal S1 (counter input signal) is received N or more times in a row, and executes the normal output mode corresponding to the current gear. That is, the control device 50 according to this embodiment executes the normal output mode when the ratio R stabilizes and falls within ±X% of the value of the gear ratio Gr for the current gear, i.e., when it is more accurately determined that metallic noises from the drivetrain and excessive pedal rotation when shifting gears are unlikely to occur. Therefore, the electrically power-assisted bicycle 1 according to this embodiment can suppress metallic noises and excessive pedal rotation when shifting gears.

[0074] Second Embodiment Next, an electrically assisted bicycle according to a second embodiment will be described. The electrically assisted bicycle of this embodiment differs from the electrically assisted bicycle 1 of the first embodiment mainly in that the method for determining the current gear (step St3 shown in FIG. 4) is different from step St3 of the electrically assisted bicycle of the first embodiment.

[0075] More specifically, the electrically power assisted bicycle 200 of this embodiment differs from the electrically power assisted bicycle 1 of the first embodiment in that, as shown in Figure 5, it has a determination unit 1556 that is different from the determination unit 56 of the electrically power assisted bicycle 1 of the first embodiment, that it determines the current gear by performing a gear ratio state determination process described below in step St3 of Figure 4, and that, while the electrically power assisted bicycle 1 of the first embodiment can use either a hall sensor or the like that detects the rotation speed Nm (rpm) of the motor 40 or a sensor that directly detects the rotation speed Nc (rpm) of the chain ring CR (wheel) as the second sensor 6, the electrically power assisted bicycle 200 of this embodiment uses the former (a hall sensor or the like that detects the rotation speed Nm (rpm) of the motor 40), but is generally similar in other respects to the electrically power assisted bicycle 1. Therefore, with regard to this embodiment, these differences will mainly be described, and other components will be designated by the same reference numerals as in the first embodiment and will not be described again.

[0076] In this embodiment, the motor rotation speed and wheel rotation speed are measured to determine the current gear ratio (current gear) of the electrically assisted bicycle. However, due to issues with the accuracy of the rotation speed sensor, a situation may arise in which it is unclear which of the adjacent gear ratios is correct. For example, even when gear G3 (3rd gear) is set, the results of measuring the motor rotation speed and wheel rotation speed may not indicate whether gear G2 (2nd gear) or gear G3 (3rd gear) is set. In this situation, if it is erroneously determined that gear G2 is set, the electrically assisted bicycle may behave in an unexpected manner. However, this embodiment makes it possible to accurately determine the situation in which it is unclear which of the adjacent gear ratios (gears) is correct. This point will be explained below.

[0077] As an example of gear positions for the sprocket SP of the electrically assisted bicycle 200 of this embodiment, the position with 36 gear teeth may be the first gear, the position with 30 gear teeth may be the second gear, and the position with 26 gear teeth may be the third gear. Gear G1 (first gear) is the lightest, and gear G9 (ninth gear) is the heaviest. Table 1 shows the gear (speed) settings of this embodiment. The tables shown below, including Table 1, may be stored in the memory unit 58 of the control circuit 50a (see FIG. 2), for example. The ratio of the number of teeth on the rear (sprocket SP) to the number of teeth on the front (chain ring CR) (rear tooth number / front tooth number) corresponds to the ratio (theoretical value) of the rotation speeds of the rear and front, and this theoretical value (i.e., gear ratio Gr) is calculated based on the number of gear teeth (n) of the rear (sprocket SP) based on the above-mentioned formula (A). ｓ ｉ ) / Front (chain ring CR) gear tooth count (n ｃ ) In Table 1, only the third decimal place is shown, but in actual calculations, the fourth decimal place and below are also used. In this embodiment, the lower limit of the threshold value used for determination is 90% of the theoretical value of the ratio of the rotation speeds, and the upper limit of the threshold value is 110% of the theoretical value of the ratio of the rotation speeds, but the upper and lower limits of the threshold value can be set arbitrarily.

[0078]

[0079] On the other hand, the actual rotation speed ratio R is expressed by the above-mentioned formula (1). In the gear ratio state determination process described below, the control device 50 determines whether the ratio R, i.e., the magnitude of formula (1), is included within a predetermined range (threshold range in Table 1) corresponding to each gear ratio Gr.

[0080] 5, the power-assisted bicycle 200 has the same configuration as the power-assisted bicycle 200 except for the configuration of the determination unit 1556. Therefore, the following description will focus on the determination unit 1556, and detailed description of the other components will be omitted.

[0081] FIG. 6 is a block diagram showing the functional configuration of the determination unit 1556. As shown in FIG. 6, the determination unit 1556 has, as functional blocks, for example, a rotation speed calculation unit 1541, an i comparison unit 1542, a threshold comparison unit 1543, a gear ratio setting unit 1544, an i setting unit 1545, a C setting unit 1546, and a count threshold comparison unit 1547. The rotation speed calculation unit 1541, the i comparison unit 1542, the threshold comparison unit 1543, the gear ratio setting unit 1544, the i setting unit 1545, the C setting unit 1546, and the count threshold comparison unit 1547 are realized, for example, by a processor in a program processing device serving as the control circuit 50a executing various arithmetic processes in accordance with various programs stored in the above-mentioned storage devices, including the storage unit 58, and controlling peripheral circuits such as a counter and an A / D conversion circuit. Note that the determination unit 1556 may have other functional blocks. Furthermore, the third calculation unit 53 described in the first embodiment may also function as the rotation speed calculation unit 1541. When the third calculation unit 53 also functions as the rotation speed calculation unit 1541, the determination unit 1556 may include the third calculation unit 53 as a functional block. The functions and operations of the rotation speed calculation unit 1541, the i comparison unit 1542, the threshold comparison unit 1543, the gear ratio setting unit 1544, the i setting unit 1545, the C setting unit 1546, and the count threshold comparison unit 1547 will be described using a flowchart of the gear ratio state determination process described later.

[0082] In the electrically power assisted bicycle 200 of this embodiment, the flow of step St3 for determining the current gear differs from step St3 in the electrically power assisted bicycle 1 of the first embodiment. Figure 7(a) is a flowchart for explaining some of the steps in the control of the electrically power assisted bicycle 200 of this embodiment, specifically, a flowchart for explaining the control performed in step St3 in the electrically power assisted bicycle 200. Figure 7(b) is a timing chart for explaining the control shown in Figure 7(a).

[0083] As shown in FIG. 7A, in this embodiment, steps St1100, St1200, and St1300 are performed in step St3. In step St1100, the control device 50 detects whether the gear ratio (the stage of the sprocket SP) has changed from the first gear ratio (first stage) to the second gear ratio (second stage). The time when the gear ratio is changed from the first gear ratio to the second gear ratio is defined as t=t10 (see FIG. 7B). In step St1200, the control device 50 performs a gear ratio state determination process, which will be described later. In step St1300, the control device 50 controls the pedal assist corresponding to the second gear ratio to start. The time when the pedal assist corresponding to the second gear ratio starts is defined as t=t11 (see FIG. 7B). The time from when the gear ratio is changed from the first gear ratio to the second gear ratio until when pedal assist corresponding to the second gear ratio begins is (t11-t10). At this point, the processing of step St3 in this embodiment ends, but in this embodiment, this processing is performed every time the gear ratio (speed) is changed.

[0084] For example, if the time when the gear ratio is changed from the third to the fourth gear ratio is t=t12 (see FIG. 7B), and the time when pedal assist corresponding to the fourth gear ratio starts is t=t13 (see FIG. 7B), the time from when the gear ratio is changed from the third to the fourth gear ratio to when pedal assist corresponding to the fourth gear ratio starts is (t13-t12). In the present invention, due to the gear ratio state determination process described below, the time (t11-t10) from when the gear ratio is changed from the first to the second gear ratio to when pedal assist corresponding to the second gear ratio starts is different from the time (t13-t12) from when the gear ratio is changed from the third to the fourth gear ratio to when pedal assist corresponding to the fourth gear ratio starts.

[0085] FIG. 8 is a timing diagram illustrating other control in this embodiment. Consider the case where the control device 50 is activated at time t=t20 from a stopped state. Pedal assist does not begin immediately upon activation, but rather after a predetermined time has elapsed. For example, assume that pedal assist corresponding to the gear ratio set at activation begins at time t=t21 shown in FIG. 8 . Consider the case where the gear ratio is changed at time t=t22, a predetermined time after activation of the control device 50. As with activation of the control device 50, pedal assist at the changed gear ratio is not applied immediately upon change of the gear ratio, but is applied after a predetermined time has elapsed. For example, assume that pedal assist corresponding to the changed gear ratio begins at time t=t23. In this embodiment, due to the gear ratio state determination process described below, the time from activation of the stopped control device 50 to the start of pedal assist corresponding to the gear ratio (t21-t20) is longer than the time from the change of the gear ratio to the start of pedal assist corresponding to the changed gear ratio (t23-t22).

[0086] Here, the time until pedal assist corresponding to the gear ratio starts may be, for example, within the time required for one rotation of the wheel. Specifically, the times (t11-t10), (t13-t12), (t21-t20), and (t23-t22) may be within the time required for one rotation of the rear wheel 3.

[0087] FIG. 9 is a timing diagram illustrating other control in this embodiment. Assume that the gear ratio is changed to a predetermined gear ratio at time t=t30 shown in FIG. 9 . At time t=t31, which is before the first period p1 has elapsed after the change to the predetermined gear ratio, the control device 50 determines (provisionally determines) a candidate for the predetermined gear ratio using a gear ratio state determination process described below. For example, gears G2 and G3 (second and third gears) are determined (provisionally determined) as candidates. At time t=t32, which is after the first period p1 has elapsed but before the second period p2 has elapsed, the control device 50 determines the predetermined gear ratio from the candidate predetermined gear ratios using a gear ratio state determination process described below. For example, from the two candidates (gears G2 and G3), the control device 50 determines that gear G3 (third gear) is the current gear ratio (current gear).

[0088] Here, it is preferable that the period including the first period p1 and the second period p2 is, for example, within the time required for one rotation of the wheel (rear wheel 3).

[0089] In addition, possible methods for checking whether a certain electrically assisted bicycle has the time relationship (time lag) that is a characteristic feature of the present invention include checking the display (display device) that shows the gear position, checking that the assist output is suppressed until the gear position is determined, and checking that a time lag occurs in the assist output due to motor current, etc.

[0090] FIG. 10 is a flowchart illustrating the gear ratio status determination process (step St1200 shown in FIG. 7 ). In the following description, it is assumed that the current gear ratio (current gear) is set to gear G3 (3rd gear). However, as described above, it may be impossible to determine whether the current gear is set to gear G2 (2nd gear) or gear G3 (3rd gear) based on the results of measuring the motor rotation speed and the wheel rotation speed. The situation in which it is unclear which of the adjacent gear ratios is correct can occur, for example, when the gear ratio is changed or when the system (control device 50) is started from a stopped state and pedaling begins. According to the power-assisted bicycle 200 of this embodiment, the gear ratio status determination process shown in FIG. 10 allows the current gear (speed) to be provisionally determined or confirmed. Example 1 shows a case where the rotation speed ratio remains unchanged at R=0.63, Example 2 shows a case where the rotation speed ratio changes from R=0.63 to R=0.55, and Example 3 shows a case where the rotation speed ratio changes from R=0.55 to R=0.63.

[0091] In Example 1, the rotation speed ratio remains constant at R = 0.63, and each time a signal indicating the vehicle speed of the electrically assisted bicycle 200 (vehicle speed pulse) arrives, the count value C for gear G2 (second gear) and gear G3 (third gear) increases, and when count value C exceeds the count threshold, gear G2 (second gear) and gear G3 (third gear) are "provisionally determined." This will be described in detail below with reference to the flowchart in Figure 10. In this embodiment, the first sensor 5 uses a sensor that outputs 12 pulses (hereinafter referred to as vehicle speed pulses) per rotation of the wheel.

[0092] In step St1211, the rotation speed calculation unit 1541 receives a signal indicating the rotation speed Nw (rpm) of the wheel from the first calculation unit 51 and detects the timing to change the vehicle speed (whether a 1 / 12 vehicle speed pulse has arrived). Hereinafter, the timing to change the vehicle speed will be referred to as the vehicle speed change timing. At the vehicle speed change timing (when a 1 / 12 vehicle speed pulse has arrived), in step S1212, the rotation speed calculation unit 1541 calculates the rotation speed ratio R (the actual rotation speed ratio) according to the above-described formula (1) based on the signal from the first calculation unit 51 and the signal from the second calculation unit 52 indicating the rotation speed Nm (rpm) of the motor 40. In the first embodiment, the ratio R is assumed to be 0.63.

[0093] In step St1213, the i comparison unit 1542 compares i with Ngear. The initial value of i is 1, and Ngear is the number of gear ratios (the number of stages of the sprocket SP), which is 9 in this embodiment. Here, since i≠9, the process proceeds to step St1214. In step St1214, the threshold comparison unit 1543 checks whether the ratio R=0.63 is within the threshold range. According to Table 1, the threshold for i=1 is 0.736 to 0.900, and the ratio R=0.63 is not within the threshold range, so the process proceeds to step St1215. In step St1215, the gear ratio setting unit 1544 checks whether the gear ratio state of gear G1 is "provisional" or "determined." As shown in Table 2, the initial values ​​of the gear ratio states of all gears G1 to G9 are "undetermined," and the gear ratio state of gear G1 is also "undetermined," so the process proceeds to step St1221. In step St1221, the i setting unit 1545 counts up i, and the process returns to step St1213.

[0094] In step St1213, the i comparison unit 1542 compares i with Ngear. Since i=2, the process proceeds to step St1214. In step St1214, the threshold comparison unit 1543 checks whether the ratio R=0.63 is within the threshold range. According to Table 1, the threshold for i=2 is 0.614 to 0.750, and the ratio R=0.63 is within the threshold range, so the process proceeds to step St1216. In step St1216, the C setting unit 1546 counts up the count value C of the gear G2 (second gear). Specifically, the count value C of the gear G2 (second gear) in Table 3 is changed from 0 to 1. In the tables shown below, including Table 3, the parts changed in this step are marked with an *. In step St1217, the count threshold comparison unit 1547 compares the count value C of gear G2 with the count threshold. The count threshold is a number indicating how many consecutive times the gear (speed) has satisfied the threshold, and is set to 6 in this embodiment. Since C<6, the process proceeds to step St1215. Note that if the gear (speed) determination is to be made faster, the count threshold should be a small number, while if the gear (speed) determination is to be made more accurate, the count threshold should be a large number. The count threshold can be set arbitrarily. In step St1215, the gear ratio setting unit 1544 checks whether the gear ratio state of gear G2 is "provisionally determined" or "determined." As shown in Table 3, the gear ratio state of gear G2 is "undetermined," so the process proceeds to step St1221. In step St1221, the i setting unit 1545 counts up i and returns to step St1213.

[0095] In step St1213, the i comparison unit 1542 compares i with Ngear. Since i=3, the process proceeds to step St1214. In step St1214, the threshold comparison unit 1543 checks whether the ratio R=0.63 is within the threshold range. According to Table 1, the threshold for i=3 is 0.532 to 0.650, and the ratio R=0.63 is within the threshold range, so the process proceeds to step St1216. In step St1216, the C setting unit 1546 counts up the count value C of gear G3 (3rd gear). Specifically, the count value C of gear G3 in Table 4 is changed from 0 to 1. In step St1217, the count threshold comparator 1547 compares the count value C of gear G3 (3rd gear) with the count threshold (6 in this embodiment). Since C<6, the process proceeds to step St1215. In step St1215, the gear ratio setting unit 1544 checks whether the gear ratio state of gear G3 is "provisionally determined" or "determined." As shown in Table 4, the gear ratio state of gear G3 is "undetermined," so the process proceeds to step St1221. In step St1221, the i setting unit 1545 counts up i and returns to step St1213.

[0096] In step St1213, the i comparison unit 1542 compares i with Ngear. Since i=4, the process proceeds to step St1214. In step St1214, the threshold comparison unit 1543 checks whether the ratio R=0.63 is within the threshold range. According to Table 1, the threshold for i=4 is 0.470 to 0.535, and the ratio R=0.63 is not within the threshold range, so the process proceeds to step St1215. In step St1215, the gear ratio setting unit 1544 checks whether the gear ratio state of gear G4 is "provisionally determined" or "determined." As shown in Table 4, the gear ratio state of gear G4 is "undetermined," so the process proceeds to step St1221. In step St1221, the i setting unit 1545 counts up i and returns to step St1213.

[0097] Since i=5 to 9 are the same as the case of i=4 described above, in step St1221, the i setting unit 1545 counts up i and skips to i=10.

[0098] In step St1213, the i comparison unit 1542 compares i with Ngear. Since i=9, the process proceeds to step St1222. In step St1222, the i setting unit 1545 resets i=1, and then the process proceeds to step St1223. In step St1223, the gear ratio setting unit 1544 checks whether there is one or more gear ratio states of "provisional determination" or "confirmed" among the gear ratio states of all gears (speeds). As shown in Table 4, the gear ratio states of all gears (speeds) are "undetermined," so the process proceeds to step St1224. In step St1224, the gear ratio setting unit 1544 sets the gear ratio states of all gears (speeds) to "undetermined." In Example 1, since the gear ratio states of all gears (speeds) are already "undetermined," nothing is done and the process returns to step St1211.

[0099] In step St1211, the rotation speed calculation unit 1541 receives a signal indicating the rotation speed Nw (rpm) of the wheel from the first calculation unit 51 and detects the timing of a vehicle speed change (whether a 2 / 12 vehicle speed pulse has arrived). At the timing of the vehicle speed change (when a 2 / 12 vehicle speed pulse has arrived), in step St1212, the rotation speed calculation unit 1541 calculates the ratio R based on the signal from the first calculation unit 51 and the signal indicating the rotation speed Nm (rpm) of the motor 40 from the second calculation unit 52. In the first embodiment, the ratio R is assumed to remain unchanged at 0.63. Therefore, when i = 1, steps St1212 to St1221 are the same as in the case of the 1 / 12 vehicle speed pulse described above. Therefore, in step St1221, the i setting unit 1545 counts up i and skips until i = 2.

[0100] In step St1213, the i comparison unit 1542 compares i with Ngear. Since i=2, the process proceeds to step St1214. In step St1214, the threshold comparison unit 1543 checks whether the ratio R=0.63 is within the threshold range. According to Table 1, the threshold for i=2 is 0.614 to 0.750, and the ratio R=0.63 is within the threshold range, so the process proceeds to step St1216. In step St1216, the C setting unit 1546 counts up the count value C of gear G2 (second gear). Specifically, the count value C of gear G2 (second gear) in Table 5 is changed from 1 to 2. In step St1217, the count threshold comparator 1547 compares the count value C of gear G2 (second gear) with the count threshold (6 in this embodiment). Since C<6, the process proceeds to step St1215. In step St1215, the gear ratio setting unit 1544 checks whether the gear ratio state of gear G2 is "provisionally determined" or "determined." As shown in Table 5, the gear ratio state of gear G2 is "undetermined," so the process proceeds to step St1221. In step St1221, the i setting unit 1545 counts up i and returns to step St1213.

[0101] In step St1213, the i comparison unit 1542 compares i with Ngear. Since i=3, the process proceeds to step St1214. In step St1214, the threshold comparison unit 1543 checks whether the ratio R=0.63 is within the threshold range. According to Table 1, the threshold for i=3 is 0.532 to 0.650, and the ratio R=0.63 is within the threshold range, so the process proceeds to step St1216. In step St1216, the C setting unit 1546 counts up the count value C of gear G3 (3rd gear). Specifically, the count value C of gear G3 (3rd gear) in Table 6 is changed from 1 to 2. In step St1217, the count threshold comparator 1547 compares the count value C of gear G3 (3rd gear) with the count threshold (6 in this embodiment). Since C<6, the process proceeds to step St1215. In step St1215, the gear ratio setting unit 1544 checks whether the gear ratio state of gear G3 is "provisionally determined" or "determined." As shown in Table 6, the gear ratio state of gear G3 is "undetermined," so the process proceeds to step St1221. In step St1221, the i setting unit 1545 counts up i and returns to step St1213.

[0102] Similarly, at the subsequent vehicle speed change timings (when the 3 / 12, 4 / 12, and 5 / 12 vehicle speed pulses arrive), as shown in Table 7, the C setting unit counts up the count value C for gears G2 and G3.

[0103] The flow for each vehicle speed change timing (3 / 12, 4 / 12, 5 / 12 vehicle speed pulse) is the same as that described above. Also, in the flow for the vehicle speed change timing (6 / 12 vehicle speed pulse), when i=1, steps St1212 to St1221 are the same as those for each vehicle speed change timing (1 / 12, 2 / 12, 3 / 12, 4 / 12, 5 / 12 vehicle speed pulse) described above, so in step St1221, the i setting unit 1545 counts up i and skips until i=2.

[0104] In step St1213, the i comparison unit 1542 compares i with Ngear. Since i=2, the process proceeds to step St1214. In step St1214, the threshold comparison unit 1543 checks whether the ratio R=0.63 is within the threshold range. According to Table 1, the threshold for i=2 is 0.614 to 0.750, and the ratio R=0.63 is within the threshold range, so the process proceeds to step St1216. In step St1216, the C setting unit 1546 counts up the count value C of gear G2 (second gear). Specifically, the count value C of gear G2 in Table 8 is changed from 5 to 6. In step St1217, the count threshold comparison unit 1547 compares the count value C of the gear G2 (second gear) with the count threshold (6 in this embodiment). Since 6≦C, the process proceeds to step St1218. In step St1218, the gear ratio setting unit 1544 checks whether the gear ratio state of the gear G2 is "excluded." As shown in Table 8, the gear ratio state of the gear G2 is "undetermined," so the process proceeds to step St1219. In step St1219, as shown in Table 9, the gear ratio setting unit 1544 changes the gear ratio state of the gear G2 (second gear) from "undetermined" to "provisional determination."

[0105] Similarly, in the loop of vehicle speed change timing (6 / 12 vehicle speed pulse), the count value C of gear G3 also becomes 6, so as shown in Table 10, the gear ratio setting unit 1544 also changes the gear ratio state of gear G3 (3rd gear) to "tentative judgment."

[0106] Since i = 4 to 8 are the same as for each of the vehicle speed change timings described above (1 / 12, 2 / 12, 3 / 12, 4 / 12, 5 / 12 vehicle speed pulses), in step St1221, the i setting unit 1545 counts up i and skips until i = 9.

[0107] In step St1213, the i comparison unit 1542 compares i with Ngear. Since i=9, the process proceeds to step St1222. In step St1222, the i setting unit 1545 resets i=1, and then the process proceeds to step St1223. In step St1223, the gear ratio setting unit 1544 checks whether there is one or more gear ratio states that are "provisional" or "confirmed" among the gear ratio states of all gears (speeds). As shown in Table 10, the gear ratio state of gears G2 and G3 is "provisional," so the process proceeds to step St1225. In step St1225, the gear ratio setting unit 1544 checks whether there is one "provisional" gear ratio state and whether the gear ratio states above and below this state are "excluded." As shown in Table 10, the gears in the "provisional determination" gear ratio state are two, gears G2 and G3, so the process returns to step St1211.

[0108] Similarly, at subsequent vehicle speed change timings (when the 7 / 12, 8 / 12, and 9 / 12 vehicle speed pulses arrive), the C setting unit increments the count value C for gears G2 and G3, as shown in Table 11. In Example 1, the ratio R remains unchanged at 0.63, so the gear ratio state remains unchanged and the loop continues. Therefore, the gear ratio state is not determined, and both gears G2 and G3 remain in a provisionally determined state. As a result, by provisionally determining both adjacent gear ratios (gears G2 and G3) as candidates, the risk of erroneous determination can be reduced. However, if the count value C reaches the count threshold, further increments are not necessary. That is, in Table 11, the count value C for gears G2 and G3 may stop at 6.

[0109] In Example 1, the control device 50 determines one or more numerical ranges that include the gear ratio calculated by equation (1) from among the numerical ranges corresponding to multiple gear ratios (gears G1 to G9), as shown in Table 1 (step St1214), and one or more gear ratios (gears G2, G3) corresponding to the one or more numerical ranges are candidates for the specified gear ratio.

[0110] In Example 2, when the rotation speed ratio changes from the state in Example 1 (R = 0.63) to R = 0.55 and the first vehicle speed pulse arrives after the change, gear G2 (2nd) deviates from the threshold (NO in step St1214). Because gear G2 (2nd) was provisionally determined (YES in step St1215), gear G2 (2nd) is "excluded" (step St1220). Because R = 0.55 is included in the thresholds of both gear G3 (3rd) and gear G4 (4th) (step St1214), the count values ​​C of gear G3 (3rd) and gear G4 (4th) increase (step St1216) and exceed the count threshold (YES in step St1217). As a result, gear G3 (3rd) and gear G4 (4th) are "provisionally determined" (step St1219). A detailed description is given below with reference to the flowchart.

[0111] In step St1211, the rotation speed calculation unit 1541 receives a signal indicating the rotation speed of the wheel (rear wheel 3) from the first sensor 5 and detects the timing of a vehicle speed change (whether a 10 / 12 vehicle speed pulse has arrived). At the timing of the vehicle speed change (when a 10 / 12 vehicle speed pulse has arrived), in step St1212, the rotation speed calculation unit 1541 calculates the ratio R based on the signal from the first calculation unit 51 and the signal indicating the rotation speed Nm (rpm) of the motor 40 from the second calculation unit 52. In the second embodiment, the ratio R is set to 0.55.

[0112] In step St1213, the i comparison unit 1542 compares i with Ngear. Since i=1, the process proceeds to step St1214. In step St1214, the threshold comparison unit 1543 checks whether the ratio R=0.55 is within the threshold range. According to Table 1, the threshold for i=1 is 0.736 to 0.900, and the ratio R=0.55 is not within the threshold range, so the process proceeds to step St1215. In step St1215, the gear ratio setting unit 1544 checks whether the gear ratio state of the gear G1 is "provisionally determined" or "determined." As shown in Table 11, the gear ratio state of the gear G1 is "undetermined," so the process proceeds to step St1221. In step St1221, the i setting unit 1545 counts up i and returns to step St1213.

[0113] In step St1213, the i comparison unit 1542 compares i with Ngear. Since i=2, the process proceeds to step St1214. In step St1214, the threshold comparison unit 1543 checks whether the ratio R=0.55 is within the threshold range. According to Table 1, the threshold for i=2 is 0.614 to 0.750, and the ratio R=0.55 is not within the threshold range, so the process proceeds to step St1215. In step St1215, the gear ratio setting unit 1544 checks whether the gear ratio state of gear G2 is "provisional" or "confirmed." As shown in Table 11, the gear ratio state of gear G2 is "provisional," so the process proceeds to step St1220. In step St1220, as shown in Table 12, the gear ratio setting unit 1544 changes the gear ratio state of the gear G2 from "provisional determination" to "exclusion," and the C setting unit 1546 resets the count value C (to zero). In step St1221, the i setting unit 1545 counts up i, and the process returns to step St1213.

[0114] In step St1213, the i comparison unit 1542 compares i with Ngear. Since i=3, the process proceeds to step St1214. In step St1214, the threshold comparison unit 1543 checks whether the ratio R=0.55 is within the threshold range. According to Table 1, the threshold for i=3 is 0.532 to 0.650, and the ratio R=0.55 is within the threshold range, so the process proceeds to step St1216. In step St1216, the C setting unit 1546 counts up the count value C of gear G3 (3rd gear). Specifically, the count value C of gear G3 (3rd gear) in Table 13 is changed from 9 to 10. In step St1217, the count threshold comparator 1547 compares the count value C of gear G3 with the count threshold (6 in this embodiment). Since 6≦C, the process proceeds to step St1218. In step St1218, the gear ratio setting unit 1544 checks whether the gear ratio state of gear G3 (3rd gear) is "excluded." As shown in Table 13, the gear ratio state of gear G3 (3rd gear) is "provisional determination," so the process proceeds to step St1219. In step St1219, the gear ratio state of gear G3 (3rd gear) is already "provisional determination," so nothing is done and the process proceeds to step St1221. In step St1221, the i setting unit 1545 counts up i and returns to step St1213.

[0115] In step St1213, the i comparison unit 1542 compares i with Ngear. Since i=4, the process proceeds to step St1214. In step St1214, the threshold comparison unit 1543 checks whether the ratio R=0.55 is within the threshold range. According to Table 1, the threshold for i=4 is 0.470 to 0.575, and since the ratio R=0.55 is within the threshold range, the process proceeds to step St1216. In step St1216, the C setting unit 1546 counts up the count value C of gear G4 (fourth gear). Specifically, the count value C of gear G4 in Table 14 is changed from 0 to 1. In step St1217, the count threshold comparator 1547 compares the count value C of gear G4 (fourth gear) with the count threshold (6 in this embodiment). Since C<6, the process proceeds to step St1215. In step St1215, the gear ratio setting unit 1544 checks whether the gear ratio state of gear G4 (fourth gear) is "provisionally determined" or "determined." As shown in Table 14, the gear ratio state of gear G4 (fourth gear) is "undetermined," so the process proceeds to step St1221. In step St1221, the i setting unit 1545 counts up i and returns to step St1213.

[0116] Since i=5 to 9 are the same as the case of i=1 described above, in step St1221, the i setting unit 1545 counts up i and skips to i=10.

[0117] In step St1213, the i comparison unit 1542 compares i with Ngear. Since i=9, the process proceeds to step St1222. In step St1222, the i setting unit 1545 resets i=1, and then proceeds to step St1223. In step St1223, the gear ratio setting unit 1544 checks whether there is one or more gear ratio states that are "provisional" or "confirmed" among the gear ratio states of all gears (speeds). As shown in Table 14, the gear ratio state of gear G3 is "provisional," so the process proceeds to step St1225. In step St1225, the gear ratio setting unit 1544 checks whether there is one "provisional" gear ratio state and whether the gear ratio states above and below this state are "excluded." As shown in Table 14, there is only one gear whose gear ratio state is "provisional judgment", which is gear G3, and the gear ratio state of gear G2 above gear G3 is "excluded", and the gear ratio state of gear G4 below gear G3 is "undetermined", so the process returns to step St1211.

[0118] Similarly, at the subsequent vehicle speed change timings (when the 11 / 12, 12 / 12, 1 / 12, and 2 / 12 vehicle speed pulses arrive), as shown in Table 15, the C setting unit 1546 counts up the count value C of gears G3 and G4.

[0119] The flow for each vehicle speed change timing (11 / 12, 12 / 12, 1 / 12, 2 / 12 vehicle speed pulse) is the same as that described above, so in step St1216 of the loop for the vehicle speed change timing (3 / 12 vehicle speed pulse), skip is made until the count value C for gear G4 becomes 6, as shown in Table 16.

[0120] In step St1217, the count threshold comparison unit 1547 compares the count value C of gear G4 (fourth gear) with the count threshold (6 in this embodiment). Since 6≦C, the process proceeds to step St1218. In step St1218, the gear ratio setting unit 1544 checks whether the gear ratio state of gear G4 is "excluded." As shown in Table 16, the gear ratio state of gear G4 is "undetermined," so the process proceeds to step St1219. In step St1219, as shown in Table 17, the gear ratio setting unit 1544 changes the gear ratio state of gear G4 (fourth gear) from "undetermined" to "provisional determination." In step St1221, the i setting unit 1545 counts up i, and the process returns to step St1213.

[0121] Since i=5 to 9 is the same as when i=4 in the first embodiment, in step St1221, the i setting unit 1545 counts up i and skips until i=10.

[0122] In step St1213, the i comparison unit 1542 compares i with Ngear. Since i=9, the process proceeds to step St1222. In step St1222, the i setting unit 1545 resets i=1, and then the process proceeds to step St1223. In step St1223, the gear ratio setting unit 1544 checks whether there is one or more gear ratio states that are "provisional" or "confirmed" among the gear ratio states of all gears (speeds). As shown in Table 17, the gear ratio state of gears G3 and G4 is "provisional," so the process proceeds to step St1225. In step St1225, the gear ratio setting unit 1544 checks whether there is one "provisional" gear ratio state and whether the gear ratio states above and below this state are "excluded." As shown in Table 17, there are two gears, G3 and G4, in the "provisional" gear ratio state, so the process returns to step St1211. In Example 2, the gear ratio state is not determined, and both gears G3 and G4 are in a provisionally determined state. As a result, by provisionally determining both of the adjacent gear ratios (gears G3 and G4) as candidates, the risk of erroneous determination can be reduced.

[0123] In Example 3, when the rotation speed ratio changes from the state in Example 2 (R = 0.55) to R = 0.63 and the first vehicle speed pulse arrives after the change, gear G4 (4th) deviates from the threshold (NO in step St1214). Because gear G4 (4th) was provisionally determined (YES in step St1215), gear G4 (4th) is "excluded" (step St1220). At this time, gear G3 (3rd) has not yet been "excluded," and the only provisionally determined or confirmed gear ratio is gear G3 (3rd) (YES in step St1223). Because gears G2 and G4 above and below gear G3 (3rd) are "excluded," gear G3 (3rd) is "confirmed" (YES in step St1225). A detailed description will be given below with reference to the flowchart.

[0124] In step St1211, the rotation speed calculation unit 1541 receives a signal indicating the rotation speed of the wheel (rear wheel 3) from the first sensor 5 and detects the timing of a vehicle speed change (whether a 4 / 12 vehicle speed pulse has arrived). At the timing of the vehicle speed change (when a 4 / 12 vehicle speed pulse has arrived), in step St1212, the rotation speed calculation unit 1541 calculates the ratio R based on the signal from the first calculation unit 51 and the signal indicating the rotation speed Nm (rpm) of the motor 40 from the second calculation unit 52. In the third embodiment, the ratio R is set to 0.63.

[0125] In step St1213, the i comparison unit 1542 compares i with Ngear. Since i=1, the process proceeds to step St1214. In step St1214, the threshold comparison unit 1543 checks whether the ratio R=0.63 is within the threshold range. According to Table 1, the threshold for i=1 is 0.736 to 0.900, and the ratio R=0.63 is not within the threshold range, so the process proceeds to step St1215. In step St1215, the gear ratio setting unit 1544 checks whether the gear ratio state of the gear G1 is "provisionally determined" or "determined." As shown in Table 17, the gear ratio state of the gear G1 is "undetermined," so the process proceeds to step St1221. In step St1221, the i setting unit 1545 counts up i and returns to step St1213.

[0126] In step St1213, the i comparison unit 1542 compares i with Ngear. Since i=2, the process proceeds to step St1214. In step St1214, the threshold comparison unit 1543 checks whether the ratio R=0.63 is within the threshold range. According to Table 1, the threshold for i=2 is 0.614 to 0.750, and the ratio R=0.63 is within the threshold range, so the process proceeds to step St1216. In step St1216, the C setting unit 1546 counts up the count value C of gear G2 (second gear). Specifically, the count value C of gear G2 in Table 18 is changed from 0 to 1. In step St1217, the count threshold comparator 1547 compares the count value C of gear G2 (2nd gear) with the count threshold (6 in this embodiment). Since C<6, the process proceeds to step St1215. In step St1215, the gear ratio setting unit 1544 checks whether the gear ratio state of gear G2 (2nd gear) is "provisional" or "determined." As shown in Table 18, the gear ratio state of gear G2 (2nd gear) is "excluded," so the process proceeds to step St1221. In step St1221, the i setting unit 1545 counts up i and returns to step St1213.

[0127] In step St1213, the i comparison unit 1542 compares i with Ngear. Since i=3, the process proceeds to step St1214. In step St1214, the threshold comparison unit 1543 checks whether the ratio R=0.63 is within the threshold range. According to Table 1, the threshold for i=3 is 0.532 to 0.650, and the ratio R=0.63 is within the threshold range, so the process proceeds to step St1216. In step St1216, the C setting unit 1546 counts up the count value C of gear G3 (3rd gear). Specifically, the count value C of gear G3 in Table 19 is changed from 15 to 16. In step St1217, the count threshold comparator 1547 compares the count value C of gear G3 (3rd gear) with the count threshold (6 in this embodiment). Since 6≦C, the process proceeds to step St1218. In step St1218, the gear ratio setting unit 1544 checks whether the gear ratio state of gear G3 is "excluded." As shown in Table 19, the gear ratio state of gear G3 (3rd gear) is "provisional determination," so the process proceeds to step St1219. In step St1219, the gear ratio state of gear G3 (3rd gear) is already "provisional determination," so nothing is done and the process proceeds to step St1221. In step St1221, the i setting unit 1545 counts up i and returns to step St1213.

[0128] In step St1213, the i comparison unit 1542 compares i with Ngear. Since i=4, the process proceeds to step St1214. In step St1214, the threshold comparison unit 1543 checks whether the ratio R=0.63 is within the threshold range. According to Table 1, the threshold for i=4 is 0.470 to 0.575, and the ratio R=0.63 is not within the threshold range, so the process proceeds to step St1215. In step St1215, the gear ratio setting unit 1544 checks whether the gear ratio state of gear G4 (fourth gear) is "provisional" or "confirmed." As shown in Table 19, the gear ratio state of gear G4 (fourth gear) is "provisional," so the process proceeds to step St1220. In step St1220, as shown in Table 20, the gear ratio setting unit 1544 changes the gear ratio state of gear G4 (fourth gear) from "provisional determination" to "exclusion," and the C setting unit 1546 resets the count value C (to zero). In step St1221, the i setting unit 1545 counts up i, and the process returns to step St1213.

[0129] Since i=5 to 9 are the same as the case of i=1 described above, in step St1221, the i setting unit 1545 counts up i and skips to i=10.

[0130] In step St1213, the i comparison unit 1542 compares i with Ngear. Since i=9, the process proceeds to step St1222. In step St1222, the i setting unit 1545 resets i=1, and then proceeds to step St1223. In step St1223, the gear ratio setting unit 1544 checks whether there is one or more gear ratio states that are "provisional" or "confirmed" among the gear ratio states of all gears (speeds). As shown in Table 20, the gear ratio state of gear G3 is "provisional," so the process proceeds to step St1225. In step St1225, the gear ratio setting unit 1544 checks whether there is one "provisional" gear ratio state and whether the gear ratio states above and below this state are "excluded." As shown in Table 20, there is only one gear, gear G3, whose gear ratio state is "provisional," and the gear ratio state of gear G2 above gear G3 is "excluded," and the gear ratio state of gear G4 below gear G3 is also "excluded," so the process proceeds to step St1226. In step St1226, as shown in Table 21, the gear ratio setting unit 1544 changes the gear ratio state of gear G3 (3rd gear) from "provisional" to "determined." In this way, in the third embodiment, it is possible to determine with high accuracy that the current speed ratio is gear G3.

[0131] In this embodiment, in each of steps St3 and St9 in FIG. 4, the control device 50 determines that the gear ratio Gr (speed) is set when the rotation speed ratio R (actual rotation speed ratio) is within the threshold range of Table 1 for a predetermined period (e.g., the time it takes for the wheels (rear wheels 3) to make one rotation). However, even after this determination, the gear ratio state determination process continues. If the driver changes the gear ratio Gr (speed), the gear ratio (speed) determined before the change no longer satisfies equation (1). At this time, the control device 50 detects that the gear ratio Gr has been changed.

[0132] To summarize Examples 1 to 3, the determination unit 1556 is configured as follows. Based on a signal indicating the rotation speed Nw (rpm) of the wheels from the first calculation unit 51 and a signal indicating the rotation speed Nm (rpm) of the motor 40 from the second calculation unit 52, the determination unit 1556 calculates the rotation speed ratio R (actual rotation speed ratio) according to Equation (1) (steps St1211 and St1212). For all gear ratios Gr (gears G1 to G9), the determination unit 1556 checks whether the ratio R is within a threshold range (step St1214). If the ratio R is within the threshold range for one or more of all gear ratios Gr a predetermined number of times (count threshold, 6 in this embodiment) or more (step St1217), the determination unit 1556 provisionally determines one or more gear ratios Gr (gears) (step St1219). If the ratio R for a provisionally determined gear ratio Gr (gear) is no longer within the threshold range (step St1215), that gear ratio Gr (gear) is excluded (step St1220). If both gear ratios Gr (gears) adjacent to a provisionally determined gear ratio Gr (gear) are excluded (step St1225), the provisionally determined gear ratio Gr (gear) is confirmed (step St1226). In this way, with the power-assisted bicycle 200 of this embodiment, by using a hall sensor or the like that detects the rotation speed Nm (rpm) of the motor 40, the determination unit 1556 can determine the current gear with high accuracy.

[0133] FIG. 11(a) is a simulation diagram illustrating detection and motor control during gear shifting in an electrically assisted bicycle. In FIG. 11(a), the vertical axis represents the gear determination status in the software in terms of voltage output, and the horizontal axis represents time. "Uncoupled" refers to cases where assist output is suppressed at the beginning of pedaling or when a gear change is detected and assist output is suppressed. As shown in FIG. 11(a), the time ta from shifting from gear G9 (9th gear) to gear G8 (8th gear) through the gear ratio state determination process shown in FIG. 10 to gear G8 (8th gear) is longer than the time tb from shifting from gear G8 (8th gear) to gear G7 (7th gear) and gear G7 (7th gear) is fixed. A similar magnitude relationship holds, with the time tc from shifting from gear G2 (2nd gear) to gear G1 (1st gear) and gear G1 (1st gear) being the shortest. This is because heavier gears take longer to fix the gear than lighter gears because the difference in the number of teeth between the upper and lower gears is smaller. For example, as shown in Table 1, the number of teeth of gear G9 (9th gear) is 11 and the number of teeth of gear G8 (8th gear) is 13, so the difference in the number of teeth between gears G9 and G8 is 2, whereas the number of teeth of gear G2 (2nd gear) is 30 and the number of teeth of gear G1 (1st gear) is 36, so the difference in the number of teeth between gears G2 and G1 is 6. Note that the time taken to change from gear G9 (9th gear) to gear G8 (8th gear) and to be fixed as gear G8 (8th gear) is the same as the time taken to change from gear G8 (8th gear) to gear G9 (9th gear) and to be fixed as gear G9 (9th gear).

[0134] FIG. 11B is an enlarged simulation diagram of the portion of FIG. 11A in which gear G9 (9th gear) is changed to gear G8 (8th gear), and the gear ratio state determination process shown in FIG. 10 is performed to determine gear G8 (8th gear). Immediately after the gear G9 (9th gear) is changed to gear G8 (8th gear), the assist output is suppressed. Next, gear G8 (8th gear) is provisionally determined, and the voltage output becomes the voltage level of gear G8 (8th gear). Next, gear G8 and gear G7 are provisionally determined, and the voltage output becomes the voltage level between gear G8 (8th gear) and gear G7 (7th gear). Next, gear G7 (7th gear) is excluded, and only gear G8 (8th gear) is provisionally determined, and the voltage output becomes the voltage level of gear G8 (8th gear). Next, gear G9 (9th gear) is also provisionally determined, and since gear G8 (8th gear) and gear G9 (9th gear) are provisionally determined, the voltage output will be at a voltage level between gear G8 (8th gear) and gear G9 (9th gear). Finally, gear G9 (9th gear) is excluded, gear G8 (8th gear) is determined, and the voltage output will be at the voltage level of gear G8 (8th gear).

[0135] FIG. 11C is an enlarged simulation diagram of the portion of FIG. 11A in which the gear is changed from gear G2 (second gear) to gear G1 (first gear), and then the gear is determined to be gear G1 (first gear) through the gear ratio state determination process shown in FIG. 10 . Immediately after the gear is changed from gear G2 (second gear) to gear G1 (first gear), the assist output is suppressed. Next, gear G1 (first gear) is provisionally determined, and the voltage output becomes the voltage level of gear G1 (first gear). As described above, the difference in the number of teeth between gears G2 and G1 is large, so the determination is not ambiguous.

[0136] As described above, according to the power-assisted bicycle 200 of this embodiment, in addition to the advantages described in the first embodiment, the current gear can be determined with higher accuracy in step St3 shown in FIG.

[0137] Although the present invention has been described above using the first and second embodiments as examples, the present invention is not limited to these.

[0138] For example, an electric assist bicycle may be configured so that the magnitude of assist of the pedal 4 is limited based on the control described in the first and second embodiments from the time when the stopped control device 50 is started up until the time when assistance of the pedal 4 corresponding to a certain gear ratio Gr begins.

[0139] In the first and second embodiments, the control device 50 determines that the gear ratio of the current gear has been entered when the first signal S1 (counter input signal) is input N or more times in succession, and executes the normal output mode corresponding to the current gear. However, the control device 50 may determine that the gear ratio of the current gear has been entered when the first signal S1 is input to the control device 50 for the first time (once), and execute the normal output mode. That is, in this case, for example, there is no need to provide a counter 57C in the mode determination unit 57, step St7 can be omitted, and there is no need to repeat the mode determination flow MF.

[0140] While the present invention has been described above using the first and second embodiments as examples, the present invention is not limited to these, and those skilled in the art can modify the electrically assisted bicycle of the present invention as appropriate in accordance with conventional knowledge. As long as such modifications still include the configuration of the present invention, they will of course be included in the scope of the present invention.

[0141] 1,200...electrically assisted bicycle, 4...pedal, 10...reduction gear, 50...control device, Gr...gear ratio

Claims

1. An electric assist bicycle in which the magnitude of the pedal assist is restricted from when the first gear ratio is changed to the second gear ratio until the pedal assist corresponding to the second gear ratio is started.

2. The electric assist bicycle according to claim 1, wherein the restricted magnitude of the pedal assist is smaller than the magnitude of the pedal assist corresponding to the second gear ratio.

3. The electric assist bicycle according to claim 1 or 2, wherein the time from when the first gear ratio is changed to the second gear ratio until the pedal assist corresponding to the second gear ratio is started is different from the time from when the third gear ratio is changed to the fourth gear ratio until the pedal assist corresponding to the fourth gear ratio is started.

4. The electric assist bicycle according to any one of claims 1 to 3, wherein the time until the pedal assist corresponding to the second gear ratio is started is within the time taken for one rotation of the pedal.

5. A rotating device having a wheel, a control device, a speed reducer, and a motor for assisting the pedal, a sensor for detecting the rotational speed of the wheel, and a sensor for detecting the rotational speed of the motor, where Nw is the rotational speed (rpm) of the wheel, Nm is the rotational speed (rpm) of the motor, and gr ＭＤＵ is the reduction ratio of the rotating device, and the control device determines whether the magnitude of the following formula (1) is included within a predetermined range corresponding to the gear ratio. The electric assist bicycle according to any one of claims 1 to 4. Nm / (gr ＭＤＵ ・ Nw) ... Formula (1) 6. An electric assist bicycle comprising a control device, wherein the magnitude of the pedal assist is restricted from when the stopped control device is started until the pedal assist corresponding to the gear ratio is started.

7. The electric assist bicycle according to claim 6, wherein the restricted magnitude of the pedal assist is smaller than the magnitude of the pedal assist corresponding to the gear ratio.

8. The electric assist bicycle according to any one of claims 6 or 7, wherein the time until the pedal assist corresponding to the gear ratio is started is within the time taken for one rotation of the pedal.

9. A wheel, the control device, a rotating device having a speed reducer and a motor for assisting the pedal, a sensor for detecting the rotational speed of the wheel, and a sensor for detecting the rotational speed of the motor, wherein Nw is the rotational speed (rpm) of the wheel, Nm is the rotational speed (rpm) of the motor, and gr ＭＤＵ is the reduction ratio of the rotating device, and the control device determines whether the magnitude of the following formula (1) is included within a predetermined range corresponding to the reduction ratio. The electric assist bicycle according to any one of claims 6 to 8. Nm / (gr ＭＤＵ ·Nw) ··· Equation (1)

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