Power-assisted bicycle

Abstract

Provided is a control device capable of keeping abnormal noise from being produced in an electrically assisted bicycle.　In the present invention, a control device (50) causes the degree of assistance that is to be provided to the rotation of a pedal (4) when the ratio R between the speed Nw (rpm) of a wheel and the speed Nm (rpm) of a motor (40) is within a predetermined range Ra to exceed the degree of assistance that is to be provided to the rotation of the pedal (4) when the ratio R between the speed Nw (rpm) of the wheel and the speed Nm (rpm) of the motor (40) is outside the predetermined range Ra.

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, 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] On bicycles, including electrically assisted bicycles, when the pedal rotation speed is slow compared to the vehicle speed, such as when traveling downhill, the pedals spin freely and the pedal rotation does not provide propulsion. In such cases, the rider's pedaling force (treading force) is not providing propulsion, so it is preferable that the motor not provide assistance. However, when a strain-type torque sensor is used as a sensor to detect pedaling force, pedaling force is detected even when pedaling downhill, and assistance may occur when the pedal rotation speed is slow compared to the vehicle speed.

[0005] Therefore, one of the objects of the present invention is to provide an electrically assisted bicycle that can more reliably cancel the assistance of the motor when the pedal rotation speed is slow compared to the vehicle speed.

[0006] (1): In the electrically assisted bicycle of the present invention, when the rotation speed of the pedal decreases and falls below a first rotation speed, the assistance of the pedal is released, and when the rotation speed of the pedal increases and exceeds a second rotation speed, the assistance of the pedal is initiated.

[0007] (2): In (1), the second rotation speed may be greater than the first rotation speed.

[0008] (3): In (1) or (2), the first rotation speed and the second rotation speed are collectively referred to as a target rotation speed Npg, and the number of teeth of the sprocket of the electrically assisted bicycle 1 is n ｓ ｉand the number of teeth of the chain ring of the electrically assisted bicycle 1 is n ｃ When the number of rotations of the wheel of the electrically assisted bicycle is Nw, k is a positive constant less than 1, k1 is a positive constant less than 1, and k2 is a positive constant greater than k1 and less than 1, then when the target number of rotations Npg is the first number of rotations Npg1, k=k1, and when the target number of rotations Npg is the second number of rotations Npg2, k=k2, and the number of rotations Npg may be obtained by the following formula (1): Npg=k(n ｓ ｉ / n ｃ ) Nw... (1)

[0009] (4): In any of (1) to (3), the time from when the gear ratio is changed from the first to the second gear ratio until the pedal corresponding to the second gear ratio starts to be assisted may be different from the time from when the gear ratio is changed from the third to the fourth gear ratio until the pedal corresponding to the fourth gear ratio starts to be assisted.

[0010] (5) In (4), the time until the pedal assist corresponding to the second gear ratio starts may be within the time required for one rotation of the wheel.

[0011] (6): In any one of (1) to (5), the electrically assisted bicycle is provided with a wheel, a control device, a rotation device having a reducer and a motor that assists the pedals, a sensor that detects the rotation speed of the wheel, a sensor that detects the rotation speed of the motor, and a sensor that detects the rotation speed of the pedals, and 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 (E) is included within a predetermined range corresponding to the gear ratio of the electrically assisted bicycle. ＭＤＵ ・Nw)...Formula (E)

[0012] 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 configuration 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 the flow of control by the control device provided in the electrically assisted bicycle shown in FIG. 1. FIG. 11(b) is a block diagram showing the configuration 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 the control of the electrically assisted bicycle shown in FIG. 5. FIG. 11(c) is a timing diagram for explaining other controls of the electrically assisted bicycle shown in FIG. 5. FIG. 11(b) is a timing diagram for explaining other controls of the electrically assisted bicycle shown in FIG. 5. FIG. 11(c) is a flowchart for explaining the gear ratio state determination process in the electrically assisted bicycle shown in FIG. 5. FIG. 11(b) is a simulation diagram for explaining detection during gear shifting and motor control in the electrically assisted bicycle shown in FIG. 5. FIG. 11(c) 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.

[0013] 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.

[0014] First Embodiment FIG. 1 is a side view of 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 with the pedals 4 under certain 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). Therefore, the electrically assisted bicycle 1 has a gear ratio Gr corresponding to each gear of the sprocket SP. This gear ratio Gr will be described in detail later. The transmission body TC is stretched across the gear of the chain ring CR and the gear of the sprocket SP. The MDU 100 includes a motor 40 and a control device 50 that controls the driving of the motor 40 to provide assistance to the electrically assisted bicycle 1.

[0015] When a rider sits on the saddle S of the electrically assisted bicycle 1 and rotates the pedals 4, under certain 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 certain conditions, the motor 40 of the MDU 100 rotates under the control of the control device 50, and the rotation of this motor 40 provides assistance, reducing (assisting) the force exerted by the rider on the pedals 4. The transmission body TC may be a chain or a belt.

[0016] 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. 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 can 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 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.

[0017] 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 and 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.

[0018] In this embodiment, the fourth sensor 8 outputs a signal Sa to a fourth calculation unit 54 (described later) of the control device 50 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 fourth calculation unit 54 (described later) of 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 a range of 1° to 360°.

[0019] The first sensor 5 and the fourth sensor 8 may be a common sensor.

[0020] Additionally, in this embodiment, the electrically assisted bicycle 1 is equipped with a fifth sensor 9 that detects the rotation speed Np (rpm) of the pedal 4. There are no particular limitations on the fifth sensor 9 as long as it is capable of detecting the rotation speed Np (rpm) of the pedal 4, but in this embodiment, a cadence sensor is used as the fifth sensor 9. For example, the fifth sensor 9 may include a magnet attached to the crank arm that connects the pedal 4 to the crankshaft 23, and a sensor attached to the frame F, and the sensor attached to the frame F may detect the magnetic force from the magnet attached to the crank arm to detect the rotation speed Np (rpm) of the pedal 4. In this specification, "detecting the rotation speed Np (rpm) of the pedal 4" may mean that the fifth sensor 9 itself calculates the rotation speed Np (rpm) of the pedal 4, or that the fifth sensor 9 outputs a signal required to calculate the rotation speed Np (rpm) of the pedal 4 to the control device 50, and the control device 50 calculates the rotation speed Np (rpm) of the pedal 4, or that the fifth sensor 9 outputs a signal required to calculate the rotation speed Np (rpm) of the pedal 4 to another calculation device (not shown), and the calculation device that receives the output signal calculates the rotation speed Np (rpm) of the pedal 4 and outputs it to the control device 50. In this embodiment, the fifth sensor 9 outputs a signal indicating the rotation speed Np (rpm) of the pedal 4 to a determination unit 56 (described later) of the control device 50.

[0021] 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.

[0022] 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).

[0023] 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.

[0024] In this embodiment, 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.

[0025] 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 described above is a strain-type torque sensor that detects the pedal force Tf (N) applied to the pedal 4 by detecting strain in the crankshaft 23 that is deformed due to the pedal force applied to the pedal 4. Therefore, the third sensor 7 detects the strain of the crankshaft 23, thereby detecting the pedal force applied to the pedal 4, and the control device 50 controls the drive of the motor 40 based on this pedal force, etc.

[0026] 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.

[0027] 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).

[0028] 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. In other words, because the rotation of the pedals 4 (crankshaft 23) is not transmitted to the chain ring CR fixed to the output gear, 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."

[0029] On the other hand, when the rotation speed of the pedal 4 (crankshaft 23) in the forward direction reaches a certain rotation speed, the clutch couples the crankshaft 23 to the output gear, and the crankshaft 23 and the output gear rotate synchronously and integrally in the forward direction (hereinafter, this may be referred to as "synchronized rotation in the forward direction"). Thus, the rotation of the pedal 4 (crankshaft 23) is transmitted to the output gear. This rotates the chain ring CR fixed to the output gear, and the sprocket SP is coupled to the rotating shaft of 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. This transmits the driving force generated by the rotation of the pedal 4 to the rear wheel 3. 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 allows the rotational force of the motor 40 to be transmitted to the pedal 4, thereby reducing (assisting) the force required to press the pedal 4 under predetermined conditions. In the case where such synchronous forward rotation occurs, the rotation speed Np (rpm) of the pedal 4 is typically equal to the value obtained by multiplying the gear ratio Gr corresponding to the current gear stage of the sprocket SP by the rotation speed Nw (rpm) of the wheel.

[0030] As shown in FIG. 1 , a clutch RC is provided on the rotating 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 that rotates in the 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 that rotates in the 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 downhill driving, the clutch RC disengages, preventing the pedals 4 from rotating rapidly in response to the rapid wheel rotation. When the wheel rotation speed Nw (rpm) increases due to downhill driving, the clutch RC of the rear wheel 3, described below, disengages, preventing the pedals 4 from rotating rapidly in response to the rapid wheel rotation. As a result, 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. Therefore, at the time when the rotation of the sprocket SP, which rotates in the positive direction relative to the rotation direction of the rear wheel 3, is transmitted to the rear wheel 3, the metal components that make up the clutch RC of the rear wheel 3 come into contact with each other, and the rotational force of the pedal 4 and the rotational force of the motor 40 are transmitted to the rear wheel 3 via the chain ring CR, sprocket SP, transmission body TC, and clutch RC of the rear wheel 3.

[0031] 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, the fifth sensor 9, 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.

[0032] 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.

[0033] 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, an output adjustment unit 55, a determination unit 56, a storage unit (memory) 58, and a drive signal generation unit 59. 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 output adjustment unit 55, and the drive signal generation unit 59 are realized, for example, by a program processing device serving as the control circuit 50 a, in which a processor executes various arithmetic operations in accordance with various programs stored in the above-mentioned storage devices, including the storage unit 58, and controls 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.

[0034] 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. ＭＤＵmay be multiplied by the reciprocal of the rotation speed Nc (rpm) of the chainring CR (i.e., the rotation speed Np (rpm) of the pedals 4), and the current gear may be determined 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 Nc (rpm) of the chainring CR described above, the gear determination program may determine the current gear 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.

[0035] 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, and data indicating the current gear, etc. The control circuit 50a may also have other functional blocks.

[0036] Here, the table T of the gear ratio Gr will be described. Fig. 3 is a diagram showing 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. Therefore, the number of teeth of the chain ring CR is n 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 ｉ In this embodiment, the gear ratio Gr of the power-assisted bicycle 1 is defined by the following equation (A): Gr=n ｓ ｉ / nｃ 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.

[0037] 2, the control circuit 50a receives 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, the fourth sensor 8 that detects the predetermined rotation angle An of the wheel, and the fifth sensor 9 that detects the rotation speed Np of the pedal 4. The first calculation unit 51 calculates the rotation speed Nw (rpm) of the wheel based on the signal input from the first sensor 5.

[0038] The third calculation unit 53 calculates the pedal force Tf (N) applied to the pedal 4 based on the signal input from the third sensor 7, which is a strain-type torque sensor, 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.

[0039] 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 second calculation unit 52 calculates the rotation speed Nm (rpm) of the motor 40 based on a signal input from the second sensor 6, and also calculates the calculated rotation speed Nm (rpm) of the motor 40 and the reduction ratio data (reduction ratio gr of the reducer 10) stored in the memory unit 58. ＭＤＵ The rotation speed Nc (rpm) of the chain ring CR is calculated based on the rotation speed Nm (rpm) of the motor 40 multiplied by the reduction ratio gr of the reducer 10. ＭＤＵ Therefore, the second calculation unit 52 calculates the rotation speed Nc (rpm) of the chain ring CR based on the following formula (B): Nc=Nm / gr ＭＤＵ ...Formula (B)

[0040] In addition, if the second sensor 6 is a sensor that directly detects the rotation speed Nc (rpm) of the chain ring CR, the value detected by the second sensor 6 will be the value of the rotation speed Nc (rpm) of the chain ring CR as is.

[0041] Incidentally, a sensor (typically a Hall sensor) detecting the rotational speed Nm (rpm) of the motor 40 may be able to detect the rotation angle with higher accuracy than a sensor that directly detects the rotational speed Np (rpm) of the pedal (crankshaft). Therefore, by calculating the rotational speed Np (rpm) of the pedal 4 using equation (B), data on the rotational speed Np (rpm) of the pedal 4 can be obtained with higher accuracy (e.g., at a time interval desired for use in software). A first example of a case in which a sensor that detects the rotational speed Nm (rpm) of the motor 40 can more accurately obtain the rotational speed is when, in the case of a sensor that directly detects the rotational speed Np (rpm) of the pedals, the distance between the magnet on the shaft connecting both pedals 4 and the magnetic sensor changes slightly due to distortion of the shaft caused by pedal force. On the other hand, the sensor that detects the rotational speed Nm (rpm) of the motor 40 is fixed so as to always be in the same position relative to the rotor of the motor 40. Therefore, the sensor that detects the rotational speed Nm (rpm) of the motor 40 can essentially always obtain accurate magnetic data. The second case involves the influence of the power of the rotating object being detected. That is, in a sensor that detects the rotation speed Nm (rpm) of the motor 40, the motor 40 of the rotating object being detected is electrically powered, whereas in a sensor that directly detects the rotation speed Np (rpm) of the pedals, the power of the rotating object being detected is human powered. For example, if the detection cycle is set to 1 ms, the fluctuations per detection cycle are smaller for electricity than for human power, and this can be used as data in the software.

[0042] If the second sensor 6 is a sensor (e.g., a Hall sensor) that detects the rotation speed Nm (rpm) of the motor 40, the fourth calculation unit 54 may determine the current gear using a gear determination program based on the rotation speed Nc (rpm) of the chainring CR calculated by the second calculation unit 52 using equation (B) and the wheel rotation speed Nw (rpm) calculated by the first calculation unit 51. Alternatively, if the second sensor 6 is a sensor that directly detects the rotation speed Nc (rpm) of the chainring CR, the fourth calculation unit 54 may determine the current gear using a gear determination program based on the rotation speed Nc (rpm) of the chainring CR detected by the second sensor 6 and the wheel rotation speed Nw (rpm) calculated by the first calculation unit 51. The fourth calculation unit 54 stores data indicating the determined current gear in the memory unit 58, thereby overwriting (updating) the data indicating the current gear that was previously stored.

[0043] In order to determine the current gear position, a gear position sensor (not shown) that can detect the gear position of the sprocket SP may be provided. If a gear position sensor is provided, the fourth calculation unit 54 may determine the current gear position based on a signal from the gear position sensor.

[0044] When the signal Sa is input for the first time from the fourth sensor 8 to the fourth calculation unit 54 during one cycle of a step in the control described later and the current gear is calculated, the determination unit 56 reads out the table T and data indicating the calculated current gear from the storage unit 58 and specifies the gear ratio Gr of the current gear. For example, as shown in FIG. 3, when the current gear is gear i, the gear ratio Gr is n ｓ ｉ / n ｃ Then, when the signal Sa is input from the fourth sensor 8 to the fourth calculation unit 54 for the first time during one cycle of the step in the control described later and the current gear is calculated, the determination unit 56 determines the calculated gear ratio Gr(n ｓ ｉ / n ｃ) and the wheel rotation speed Nw (rpm) calculated by the first calculation unit 51, the first target rotation speed Npg1 (rpm) of the pedal 4 (hereinafter, may be simply referred to as "first rotation speed Npg1") is calculated using the following formula (C): Npg1=k1(n ｓ ｉ / n ｃ ) Nw ... (C) In equation (C), k1 is a positive constant less than 1. The value of k1 is not particularly limited, but may be, for example, 0.70 or greater and 0.80 or less, more specifically, 0.75. The determination unit 56 then determines whether the first rotation speed Npg1 (rpm) is greater than the pedal rotation speed Np (rpm) of the pedal 4 detected by the fifth sensor 9. In equation (C), the first rotation speed Npg1 (rpm) is calculated by multiplying it by a positive constant k1 less than 1. This prevents the assist from being erroneously released during normal riding due to the influence of sensor accuracy. Specifically, due to the influence of sensor accuracy, a discrepancy (error) may occur between the detected pedal rotation speed and the actual pedal rotation speed during normal riding, and this discrepancy may result in the assist being released. By multiplying by a positive constant k1 that is smaller than 1, the threshold value (i.e., the first rotation speed Npg1) is lowered, making it possible to eliminate the influence of such errors.

[0045] In this way, the determination unit 56 determines Nw as the rotation speed of the wheel, Nm as the rotation speed of the motor 40, Np as the rotation speed of the pedal 4, and gr ＭＤＵ is the reduction ratio of the reducer 10, the speed change ratio Gr(n ｓ ｉ / n ｃ ) (i.e., the rotation speed Np (rpm) of the pedal 4) is determined to be within a predetermined range (Npg1>Np) corresponding to the above equation (B).

[0046] In the present embodiment, when the rotation speed Np (rpm) of the pedal 4 is smaller than the first rotation speed Npg1 (rpm), the determination unit 56 outputs the first signal S1 to the output adjustment unit 55. Note that the determination unit 56 may also output the first signal S1 to the output adjustment unit 55 when the rotation speed Np (rpm) of the pedal 4 is equal to or smaller than the first rotation speed Npg1 (rpm).

[0047] Furthermore, when the signal Sa is input from the fourth sensor 8 to the fourth calculation unit 54 for the second time during one cycle of the control steps described later, the determination unit 56 reads out the table T and data indicating the current gear from the storage unit 58, and calculates the gear ratio Gr(n ｓ ｉ / n ｃ ) and the wheel rotation speed Nw (rpm) calculated by the first calculation unit 51, the second target rotation speed Npg2 (rpm) of the pedal 4 is calculated using the following formula (D) (hereinafter, may be simply referred to as the "second rotation speed Npg2"). Npg2=k2(n ｓ ｉ / n ｃ ) Nw ... (D) In ​​equation (D), k2 is a positive constant smaller than 1 and greater than k1. The value of k2 is not particularly limited, but may be, for example, 0.80 or greater and 0.90 or less, more specifically, 0.85. The determination unit 56 then determines whether the second rotation speed Npg2 (rpm) is greater than the rotation speed Np (rpm) of the pedal 4 detected by the fifth sensor 9. In equation (D), the second rotation speed Npg2 (rpm) is calculated by multiplying the second rotation speed Npg2 (rpm) by a positive constant k2 smaller than 1. This prevents the occurrence of a situation in which the assist is not started (resumed) at the desired timing due to the influence of sensor accuracy, even when the assist is released and the vehicle is in a normal driving state and the pedal 4 is not spinning. Furthermore, in equation (D), the second rotation speed Npg2 (rpm) is calculated by multiplying the second rotation speed Npg2 (rpm) by a constant k2 greater than k1. This prevents a difference from occurring between the second rotation speed Npg2 and the first rotation speed Npg1, preventing the cycle of assistance being released and then started (restarted) from being repeated within an undesirable short period of time.

[0048] In the present embodiment, when the rotation speed Np (rpm) of the pedal 4 is greater than the second rotation speed Npg2 (rpm), the determination unit 56 outputs the second signal S2 to the output adjustment unit 55. Note that the determination unit 56 may also output the second signal S2 to the drive signal generation unit 59 when the rotation speed Np (rpm) of the pedal 4 is equal to or greater than the second rotation speed Npg2 (rpm).

[0049] Here, if the first rotation speed Npg1 (rpm) in equation (C) and the second rotation speed Npg2 (rpm) in equation (D) are collectively referred to as the target rotation speed Npg, this target rotation speed Npg can be obtained by the following equation (1) using a constant k: Npg=k(n ｓ ｉ / n ｃ ) Nw (1) (k=k1 (in the case of the first rotation speed Npg1)) (k=k2 (in the case of the second rotation speed Npg2)) In this embodiment, k1<k2.

[0050] As described above, in this embodiment, the constant k2 in formula (D) is greater than the constant k1 in formula (C). Therefore, in this embodiment, the second rotation speed Npg2 (rpm) obtained using formula (D) tends to be greater than the first rotation speed Npg1 (rpm) obtained using formula (C), and the gear ratio Gr(n ｓ ｉ / n ｃ ) and the wheel rotation speed Nw (rpm) are the same, the second rotation speed Npg2 (rpm) is greater than the first rotation speed Npg1 (rpm).

[0051] When the second signal S2 is input from the determination unit 56, the output adjustment unit 55 outputs a fourth signal S4 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 first signal S1 is input from the determination unit 56, the output adjustment unit 55 outputs a third signal S3 indicating a torque command value obtained by suppressing the torque command value Tm (Nm) calculated by the third calculation unit 53 (hereinafter, this may be referred to as a "suppressed torque command value RTm (Nm)") to the drive signal generation unit 59.

[0052] Here, the suppression torque command value RTm (Nm) may be, for example, a value (e.g., zero) that does not drive the motor 40, or a value that indicates the torque of the motor 40 such that the drive of the motor 40 is not transmitted to the output gear. For example, it may be a torque obtained by multiplying the smallest torque (Nm) of the motor 40 in the normal output mode by a number M (0<M<1) that is smaller than 1 (i.e., a torque that is smaller than the torque in the normal output mode).

[0053] 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 fourth signal S4 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 fourth signal S4 to the drive circuit 50b, and when the third signal S3 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 third signal S3 to the drive circuit 50b. The drive signal Sd is, for example, a PWM (Pulse Width Modulation) signal.

[0054] 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 Sd, and a current detection circuit that detects the current flowing through each coil.

[0055] 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.

[0056] 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.

[0057] In this embodiment, for example, the step of starting control may be started (START) when the drive of motor 40 is started. Specifically, the step of starting control may be started when drive signal generator 59 generates drive signal Sd for driving motor 40 and outputs it to drive circuit 50b. At this time, memory unit 58 stores the gear position of sprocket SP that was set immediately before the step of control was started (START) as data indicating the current gear position.

[0058] (Step St1) The control device 50 determines whether a signal Sa indicating that the wheel has rotated a predetermined rotation angle An (deg) has been input to the fourth calculation unit 54. If the control device 50 determines that the signal Sa has been input to the fourth calculation unit 54, it proceeds to step St2 in the control, and if the control device 50 determines that the signal Sa has not been input to the fourth calculation unit 54, it returns to step St1 in the control. 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.

[0059] (Step St2) When the second sensor 6 is a sensor (for example, a Hall sensor) that detects the rotation speed Nm (rpm) of the motor 40, the control device 50 calculates the rotation speed Nm (rpm) of the motor 40 calculated by the second calculation unit 52, the rotation speed Nw (rpm) of the wheel calculated by the first calculation unit 51, and the reduction ratio data (reduction ratio gr of the reducer 10) stored in the memory unit 58 in the fourth calculation unit 54. ＭＤＵThe control unit 50 determines (calculates) the current gear based on the data indicating the current gear (Nc (rpm)) and the above-mentioned gear determination program. If the second sensor 6 is a sensor that directly detects the rotation speed Nc (rpm) of the chain ring CR, the control unit 50 determines (calculates) the current gear in the fourth calculation unit 54 based on the rotation speed Nc (rpm) of the chain ring CR detected by the second sensor 6, the wheel rotation speed Nw (rpm) calculated by the first calculation unit 51, and the above-mentioned gear determination program. If the electrically assisted bicycle 1 is equipped with a gear position sensor, the control unit 50 may determine (calculate) the current gear based on a signal from the gear position sensor. The control unit 50 overwrites (updates) the "data indicating the current gear" stored in the memory unit 58 up to that point (i.e., at the time of START) with the data indicating the current gear determined in this step, and proceeds to step St3 in the control process.

[0060] (Step St3) The control device 50 calculates the first target rotation speed Npg1 (rpm) of the pedal 4 using the above-mentioned formula (C) in the determination unit 56 based on the wheel rotation speed Nw (rpm) calculated by the first calculation unit 51, the table T stored in the storage unit 58, and the "data indicating the current gear" updated in step St2. The control device 50 stores the data of this first target rotation speed Npg1 (rpm) in the storage unit 58. Then, the control device 50 advances the control step to step St4.

[0061] (Step St4) The control device 50 reads out data on the first rotation speed Npg1 (rpm) calculated in step St3 from the storage unit 58, and the determination unit 56 determines whether the first rotation speed Npg1 (rpm) is larger than the rotation speed Np (rpm) of the pedal 4 input from the fifth sensor 9. If the rotation speed Np (rpm) of the pedal 4 input from the fifth sensor 9 is equal to or greater than the first rotation speed Npg1 (rpm), the control device 50 returns the control step to step St1. On the other hand, if the rotation speed Np (rpm) of the pedal 4 input from the fifth sensor 9 is lower than the first rotation speed Npg1 (rpm) (or is equal to or less than the first rotation speed Npg1 (rpm)), the control device 50 advances the control step to step St5. Specifically, the control device 50 outputs the first signal S1 from the determination unit 56 to the output adjustment unit 55, and advances the control to step St5.

[0062] (Step St5) When the first signal S1 is input to the output adjustment unit 55, the control device 50 causes the output adjustment unit 55 to output to the drive signal generation unit 59 a third signal S3 indicating a suppressed torque command value RTm (Nm) obtained by suppressing the torque command value Tm (Nm) calculated by the third calculation unit 53. When the third signal S3 is input to the drive signal generation unit 59, the control device 50 causes the drive signal generation unit 59 to generate a drive signal Sd for causing the motor 40 to exert a torque of the suppressed torque command value RTm (Nm) indicated by the third signal S3, and controls the drive of the motor 40 based on this drive signal Sd. That is, in this step, the drive of the motor 40 stops (or the power-assisted bicycle enters a state where it is not accelerated by the drive of the motor 40), and the assist of the power-assisted bicycle 1 by the motor 40 is canceled. The control device 50 then advances the control step to step St6.

[0063] (Step St6) The control device 50 again determines whether the signal Sa indicating that the wheel has rotated a predetermined rotation angle An (deg) has been input to the fourth calculation unit 54. If the control device 50 determines that the signal Sa has been input to the fourth calculation unit 54 (that is, if the signal Sa has been input to the fourth calculation unit 54 for the second time in one cycle of the steps in this control), the control proceeds to step St7, but if the control device 50 determines that the signal Sa has not been input to the fourth calculation unit 54, this step is repeated.

[0064] (Step St7) The control device 50 calculates the second target rotation speed Npg2 (rpm) of the pedal 4 using the above-mentioned formula (D) in the determination unit 56 based on the wheel rotation speed Nw (rpm) calculated by the first calculation unit 51, the table T stored in the memory unit 58, and the data indicating the "current gear" determined in step St2 and stored in the memory unit 58. The control device 50 stores the data of this second target rotation speed Npg2 (rpm) in the memory unit 58. Then, the control device 50 advances the control step to step St8.

[0065] (Step St8) The control device 50 reads out the data of the second rotation speed Npg2 (rpm) calculated in step St7 from the storage unit 58, and the determination unit 56 determines whether the second rotation speed Npg2 (rpm) is larger or smaller than the rotation speed Np (rpm) of the pedal 4 input from the fifth sensor 9. If the rotation speed Np (rpm) of the pedal 4 input from the fifth sensor 9 is equal to or smaller than the second rotation speed Npg2 (rpm), the control device 50 returns the control step to step St6. On the other hand, if the rotation speed Np (rpm) of the pedal 4 input from the fifth sensor 9 exceeds the second rotation speed Npg2 (rpm), the control device 50 advances the control step to step St9. Specifically, the control device 50 outputs the second signal S2 from the determination unit 56 to the output adjustment unit 55, and advances the control step to step St9.

[0066] (Step St9) When the second signal S2 is input to the output adjustment unit 55, the control device 50 causes the output adjustment unit 55 to output a fourth signal S4 indicating the torque command value Tm (Nm) calculated by the third calculation unit 53 to the drive signal generation unit 59. The control device 50 then generates a drive signal Sd in the drive signal generation unit 59 for causing the motor 40 to exert torque corresponding to the torque command value Tm (Nm) indicated by the fourth signal S4, and controls (starts) the drive of the motor 40 based on this drive signal Sd. That is, in this step, the drive of the motor 40 is started, and assistance to the pedal 4 is started (resumed). In this step, the control device 50 controls the motor 40 based on the torque command value Tm (Nm) so that the motor 40 drives in accordance with the gear determined in step St2. The control device 50 then returns the control step to step St1.

[0067] Here, the first target rotation speed Npg1 is the gear ratio Gr(n ｓ ｉ / nc) by the current wheel rotation speed Nw (rpm) and a constant k1 that is less than 1. For this reason, when the pedal 4 rotation speed Np (rpm) is equal to or greater than the first target rotation speed Npg1, it can be estimated that the pedal 4 rotation speed Np (rpm) is synchronized with the wheel rotation speed Nw (rpm), and that the pedal 4 (chain ring CR) and crankshaft 23 are rotating forward in synchronization with the output gear of the reducer 10, and the driving force of the MDU 100 is transmitted to the pedal 4. Conversely, if the rotation speed Np (rpm) of the pedal 4 is lower than the first target rotation speed Npg1, it means that the rotation speed Np (rpm) of the pedal 4 is lower than the rotation speed Nw (rpm) of the wheel, and it can be assumed that the pedal 4 (chain ring CR) and crankshaft 23 are rotating in the reverse direction and the driving force of the MDU 100 is not transmitted to the pedal 4 (the pedal 4 is spinning freely).

[0068] 4 , in the electrically assisted bicycle 1, when the rotation speed Np (rpm) of the pedal 4 decreases and falls below the first rotation speed Npg1 calculated using equation (C), the driving of the motor 40 is stopped (the assist to the pedal 4 is released), and on the other hand, when the rotation speed Np (rpm) of the pedal 4 increases and exceeds the second rotation speed Npg2, the driving of the motor 40 is started (the assist to the pedal 4 is released). In other words, in the electrically assisted bicycle 1, the assist to the pedal 4 is released when it is possible to estimate reverse rotation of the pedal 4, and the assist to the pedal 4 is released when it is possible to estimate synchronized forward rotation of the pedal 4.

[0069] Therefore, with the electrically assisted bicycle 1, it is possible to more reliably release the motor assistance when the rotational speed of the pedal 4 is slow compared to the vehicle speed (wheel rotation speed Nw (rpm)) (when the pedal 4 spins freely).Furthermore, even when a strain-type torque sensor is used as the sensor for detecting the pedal force Tf (N), it is possible to more reliably release the motor assistance when the rotational speed of the pedal 4 is slow compared to the vehicle speed.

[0070] Here, if the rotation speed Np (rpm) of the pedal 4 remains the same as the rotation speed Nw (rpm) of the wheel when the pedal 4 is not spinning, ｓ ｉ / n ｃ ) × Nw' (Nw' < Nw) and the pedals 4 start to spin freely. If the motor 40 is driving at this time, the chain ring CR will move in the same way as when the pedals 4 are not spinning freely, as shown in FIG. ｓ ｉ / n ｃ ) × Nw (rpm). The reason for this is as follows.

[0071] If the motor 40 were to decelerate in the same way as the pedals 4, the chain ring CR and sprocket SP would also decelerate, and as a result, the clutch RC of the rear wheel 3 would be disengaged (disconnected). In this case, the load seen by the motor 40 would consist only of the chain ring CR, transmission body TC, and sprocket SP, so the motor 40 would be in a substantially no-load state. When the torque of the motor 40 acts in this no-load state, the chain ring CR and sprocket SP would accelerate to a rotational speed at which a large load would be applied, that is, the wheel, vehicle body, and rider (i.e., the rotational speed at which the clutch RC of the rear wheel 3 would engage). As a result, the chain ring CR would rotate at a speed (n ｓ ｉ / n ｃ ) × Nw (rpm).

[0072] In this case, because the rotation speed Np (rpm) of the pedals 4 is slower than that of the chain ring CR, the clutch of the reducer 10 disengages, and the pedals 4 (crankshaft 23) are disconnected from the output gear of the reducer 10, resulting in all parts of the drive system moving in tandem except for the pedals 4. In other words, in this case, the motor 40 moves the power-assisted bicycle 1 even though the force exerted by the pedals 4 is not contributing to the propulsion force of the power-assisted bicycle 1.

[0073] As described above, with the electric assist bicycle 1, it is possible to more reliably cancel the motor assist when the rotation speed of the pedal 4 is slow compared to the vehicle speed (wheel rotation speed Nw (rpm)) (when the pedal 4 spins freely), thereby effectively preventing the motor 40 from moving the electric assist bicycle 1 even though the force of pedaling the pedal 4 is not contributing to the propulsion force of the electric assist bicycle 1.

[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 St2 shown in FIG. 4) is different from step St2 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 fourth calculation unit 1540 that is different from the fourth calculation unit 54 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 St2 of Figure 4, and that, while the electrically power assisted bicycle 1 of the first embodiment can use either a sensor that detects the rotation speed Nm (rpm) of the motor 40 (e.g., a Hall sensor) or a sensor that directly detects the rotation speed Nc (rpm) of the chain ring CR as the second sensor 6, the electrically power assisted bicycle 200 of this embodiment uses the former (a sensor 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 an electrically assisted bicycle. However, due to issues with sensor accuracy, a situation may arise in which it is unclear which of the adjacent gear ratios is correct. For example, even if 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 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 formula (E): R = Nm / (gr ＭＤＵ Nw) Formula (E) where Nm, Nw, and gr ＭＤＵ The meaning of is the same as in the first embodiment. In the gear ratio state determination process described below, the control device 50 determines whether the ratio R, i.e., the magnitude of equation (E), 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 fourth calculation unit 1540. Therefore, the following description will focus on the fourth calculation unit 1540, and detailed description of the other components will be omitted.

[0081] FIG. 6 is a block diagram showing the functional configuration of the fourth calculation unit 1540. As shown in FIG. 6, the fourth calculation unit 1540 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 fourth calculation unit 1540 may have other functional blocks. The functions and operations of the rotation speed calculation unit 1541, i comparison unit 1542, threshold comparison unit 1543, gear ratio setting unit 1544, i setting unit 1545, C setting unit 1546 and count threshold comparison unit 1547 will be explained using the flowchart of the gear ratio state determination process described later.

[0082] In the electrically power assisted bicycle 200 of this embodiment, the flow of steps St3 and St9 for determining the current gear differs from steps St3 and St9 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 St2 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 step St2, steps St1100, St1200, and St1300 are performed. 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 set to 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 set to 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 St2 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, the period including the first period p1 and the second period p2 is preferably equal to or less than the time required for one rotation of the wheel (rear wheel 3), for example.

[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 (E) 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] [Correction based on Rule 91 10.03.2025] 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 "provisional determination."

[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] [Correction Based on Rule 91 10.03.2025] 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 "determined." 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=10, 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] [Correction based on Rule 91 10.03.2025] 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] [Correction Based on Rule 91 10.03.2025] 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 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=10, 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=10, 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 fourth calculation unit 1540 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 fourth calculation unit 1540 calculates the rotation speed ratio R (actual rotation speed ratio) according to equation (E) (steps St1211 and St1212). If the ratio R for one or more of all gear ratios Gr (gears G1 to G9) falls within the threshold range a predetermined number of times (count threshold, 6 in this embodiment) or more (step St1217), one or more gear ratios Gr (gears) are provisionally determined (step St1219). If the ratio R for a provisionally determined gear ratio Gr (gear) is no longer within the threshold range (step St1215), the gear ratio Gr (gear) is excluded (step St1220). If both gear ratios Gr (gears) adjacent to one provisionally determined gear ratio Gr (gear) are excluded (step St1225), the provisionally determined gear ratio Gr (gear) is determined to be the gear ratio (step St1226). In this way, according to 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 fourth calculation unit 1540 can determine the current gear with higher 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 effects described in the first embodiment, the current gear can be determined with higher accuracy in step St2 shown in FIG.

[0137] 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.

[0138] 1,200...electrically assisted bicycle, 4...pedal, 10...reduction gear, 50...control device, Gr...gear ratio

Claims

1. An electric assist bicycle in which when the rotation speed of a pedal decreases and falls below a first rotation speed, the assist for the pedal is released, and when the rotation speed of the pedal increases and exceeds a second rotation speed, the assist to the pedal is started.

2. The electric assist bicycle according to claim 1, wherein the second rotation speed is greater than the first rotation speed.

3. The first rotational speed and the second rotational speed are collectively referred to as the target rotational speed Npg, and the number of teeth of the sprocket of the electric assist bicycle 1 is n ｓ ｉ and the number of teeth of the chain ring of the electric assist bicycle 1 is n ｃ and the rotational speed of the wheel of the electric assist bicycle is Nw. When k is a positive constant smaller than 1, k1 is a positive constant smaller than 1, and k2 is a positive constant larger than k1 and smaller than 1, when the target rotational speed Npg is the first rotational speed Npg1, k = k1, and when the target rotational speed Npg is the second rotational speed Npg2, k = k2, the electric assist bicycle according to claim 1 or 2, obtained by the following formula (1). Npg = k(n ｓ ｉ / n ｃ )Nw...(1) 4. The electric assist bicycle according to any one of claims 1 to 3, wherein the time from when the gear ratio is changed from a first gear ratio to a second gear ratio until the assist for the pedal corresponding to the second gear ratio is started is different from the time from when the gear ratio is changed from a third gear ratio to a fourth gear ratio until the assist for the pedal corresponding to the fourth gear ratio is started.

5. The electric assist bicycle according to claim 4, wherein the time until the assist for the pedal corresponding to the second gear ratio is started is within the time taken for one rotation of the wheel.

6. 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, a sensor for detecting the rotational speed of the motor, and a sensor for detecting the rotational speed of the pedal, where Nw is the rotational speed of the wheel (rpm), Nm is the rotational speed of the motor (rpm), and gr ＭＤＵ is the reduction ratio of the rotating device, and the control device determines whether the magnitude of the following formula (E) is included within a predetermined range corresponding to the gear ratio of the electric assist bicycle according to any one of claims 1 to 5. Nm / (gr ＭＤＵ ·Nw) ··· Formula (E)

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