WO2025154383A1 - Control device and electrically assisted bicycle - Google Patents

Abstract

The present invention provides a control device that makes it possible to suppress the occurrence of an abnormal sound in an electrically assisted bicycle and an electrically assisted bicycle that is capable of suppressing the occurrence of an abnormal sound.　A control device (50) sets a level at which rotation of pedals (4) is assisted when a ratio (R) between a rotational speed (Nw) (rpm) of wheels and a rotational speed (Nm) (rpm) of a motor (40) is within a prescribed range (Ra) such that said level is higher than a level at which the rotation of the pedals (4) is assisted when the ratio (R) between the rotational speed (Nw) (rpm) of the wheels and the rotational speed (Nm) (rpm) of the motor (40) is outside the prescribed range.

Description

Control device and electric assist bicycle

The present invention relates to a control device and an electrically assisted bicycle.

A control device that determines whether or not assistance is required based on the force applied to the pedals, and if assistance is required, rotates the motor to provide assistance to the electrically assisted bicycle, and an electrically assisted bicycle equipped with such a control device are known (see, for example, Patent Document 1).

JP 2020-90109 A

Typically, in an electrically assisted bicycle, when the rotation of the pedals (i.e. the rotation of the crankshaft connected to the pedals) is under certain conditions, the driving force of a motor drive unit (MDU) equipped with a motor is transmitted to the crankshaft via a clutch, and the rotation of the pedals is assisted based on the control of the control device.

When the clutch is not transmitting the driving force of the motor drive unit to the crankshaft, for example, if the pedal is pressed in a direction to accelerate the electric assist bicycle, the clutch transitions to a state where it transmits driving force to the crankshaft. At this time, if the motor suddenly starts to operate, for example, by pressing hard on the pedal to move the electric assist bicycle that has stopped, metal parts such as the clutch may suddenly come into contact, and abnormal noises such as metallic sounds may be generated due to this sudden contact.

Therefore, one of the objectives of the present invention is to provide a control device that can prevent abnormal noises from occurring in an electrically assisted bicycle, and an electrically assisted bicycle that can prevent the occurrence of abnormal noises.

The control device according to the present invention increases the magnitude of assistance for pedal rotation when the ratio of the rotation speed of the wheel to the rotation speed of the motor is within a predetermined range, compared to the magnitude of assistance for pedal rotation when the ratio of the rotation speed of the wheel to the rotation speed of the motor is outside the predetermined range.

Furthermore, an electrically assisted bicycle according to the present invention includes the above-mentioned control device, a rotating device having the motor and a reducer, the pedal, and the wheel, and when the pedal is assisted by the rotating device, the magnitude of the following equation (1) is within a predetermined range, where 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 rotating device.
Nm/(Nw・gr _MDU )...(1)

Furthermore, in the above-mentioned electrically assisted bicycle, the magnitude of the torque of the motor outside the specified range may be smaller than the magnitude of the torque of the motor within the specified range.

1 is a side view showing an example of an electrically assisted bicycle according to an embodiment of the present invention. 2 is a diagram showing a schematic configuration of a rotating device provided in the power-assisted bicycle shown in FIG. 1 . 2 is a block diagram showing the configuration of a control device, a sensor, and a motor provided in the power-assisted bicycle shown in FIG. 1 . 4 is a flowchart showing an example of a flow of control by a control device provided in the power-assisted bicycle shown in FIG. 1 .

Below, examples of embodiments for implementing the control device and electrically assisted bicycle according to the present invention are illustrated with the accompanying drawings. The embodiments illustrated below are intended to facilitate understanding of the present invention, and are not intended to limit the interpretation of the present invention. The present invention can be modified or improved from the following embodiments without departing from the spirit of the invention. In addition, in the above attached drawings, the dimensions of each component may be exaggerated or reduced, and hatching may be omitted, in order to facilitate understanding.

FIG. 1 is a side view showing an electrically assisted bicycle according to one embodiment of the present invention. As shown in FIG. 1, the electrically assisted bicycle 1 includes a frame F, a handlebar H, a saddle S, a transmission body C, 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 sprocket SP is attached to the rear wheel 3. The transmission body C is stretched across the chain ring CR and 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. When a rider sits on the saddle S of the electrically assisted bicycle 1 and rotates the pedals 4, under certain conditions, a driving force is transmitted to the wheel (typically the rear wheel 3) via the chain ring CR, the sprocket SP, and the transmission body C, enabling forward travel. At this time, under certain conditions, the motor 40 of the MDU 100 rotates based on the control of the control device 50, and the force exerted by the driver on the pedal 4 is reduced (assisted) by the assistance provided by the rotation of the motor 40. The transmission body C may be a chain or a belt.

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 assisted bicycle 1. In this specification, "detecting the wheel rotation speed Nw (rpm) and the vehicle speed Vb (km/h)" may mean that the first sensor 5 itself calculates the wheel rotation speed Nw (rpm) and the vehicle speed Vb (km/h), that the first sensor 5 outputs a signal required to calculate the wheel rotation speed Nw (rpm) and the vehicle speed Vb (km/h) to the control device 50, and the control device 50 calculates the wheel rotation speed Nw (rpm) and the vehicle speed Vb (km/h), or that the first sensor 5 outputs a signal required to calculate the wheel rotation speed Nw (rpm) and the vehicle speed Vb (km/h) to another calculation device (not shown), and the calculation device to which the output signal is input calculates the wheel rotation speed Nw (rpm) and the vehicle speed Vb (km/h) and outputs them to the control device 50. FIG. 1 shows an example in which the first sensor 5 is disposed near the rotation axis of the rear wheel 3. The first sensor 5 may be a known sensor capable of detecting the wheel rotation speed Nw (rpm) and the vehicle speed Vb (km/h) or outputting a signal required to calculate the wheel rotation speed Nw (rpm) and the vehicle speed Vb (km/h). 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), or an optical sensor capable of detecting the wheel rotation speed Nw (rpm) and the vehicle speed Vb (km/h). The first sensor 5 may be located at any position where the wheel rotation speed Nw (rpm) and the vehicle speed Vb (km/h) can be detected, and may be located, for example, away from the rotation axis of the front wheel 2 or the rear wheel 3.

Similarly, a fourth sensor 8 for detecting a predetermined rotation angle An (deg) of the wheel is disposed, for example, near the rotation axis of the front wheel 2 or the rear wheel 3. In this specification, "detecting a 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 that 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 that the calculation device to which the output signal is input calculates the predetermined rotation angle An (deg) of the wheel and outputs it to the control device 50. FIG. 1 shows an example in which the fourth sensor 8 is disposed near the rotation axis of the rear wheel 3. The fourth sensor 8 may be a known sensor capable of detecting the predetermined rotation angle An (deg) of the wheel or capable of outputting a signal required 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) of the wheel, 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, away from the rotation axis of the front wheel 2 or the rear wheel 3.

In this embodiment, the fourth sensor 8 outputs a signal Sa to the control device 50 each time the wheel (e.g., rear wheel 3) rotates a predetermined rotation angle An (deg). That is, the fourth sensor 8 outputs a signal Sa to the control device 50 indicating that the wheel has rotated a predetermined rotation angle An (deg). The predetermined rotation angle An (deg) is not particularly limited, but may be, for example, 30°, 120°, 90°, 60°, 45°, 15°, 10°, or any predetermined angle selected within the range of 1° to 360°.

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

The MDU 100 and the battery B are typically arranged around the crankshaft 23 connected to the pedal 4. Figure 2 is a schematic diagram showing the configuration of the MDU 100.

1 and 2, 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, the control device 50, etc. inside. The rotation device 70 has a motor 40, a speed reducer 10, and a third sensor 7 as a torque sensor. In FIG. 1, the rotation device 70 and the control device 50 are shown by 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. A battery B supplies power to the motor 40 and the control device 50, and the motor 40 and the control device 50 operate using this power.

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 reduction gear 10. In this specification, "rotation of the pedal 4" refers to the rotation of the pedal 4 around the crankshaft 23. In this specification, "assist" also includes reducing the force (pressure) required to rotate the pedal 4 (push the pedal 4) by human power. The motor 40 is not particularly limited, but may be, for example, a brushless DC motor having coils corresponding to three phases (U phase, V phase, and W phase).

As shown in FIG. 2, a second sensor 6 is disposed on the motor 40 for detecting 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), 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 calculation device (not shown), and the calculation device that receives the output signal calculates the rotation speed Nm (rpm) of the motor 40 and outputs it to the control device 50. FIG. 2 shows an example in which the second sensor 6 is mounted on the motor 40, but the position of the second sensor 6 is not particularly limited as long as 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 outputting a signal required 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.

As shown in FIG. 2, the crankshaft 23 passes through the inside of the housing 60 of the MDU 100. In the extension direction (axial or longitudinal direction) of the crankshaft 23, the crankshaft 23 has one end 23a and the other end 23b. The one end 23a and the other end 23b are outside the housing 60, and the pedal 4 is fixed to each of the one end 23a and the other end 23b. The crankshaft 23 rotates when the pedal 4 is pedaled. Note that FIG. 1 is a view of the electric assisted bicycle 1 looking in the extension direction (axial or longitudinal direction) of the crankshaft 23. The above-mentioned third sensor 7 is housed inside the housing 60 and may be attached, for example, so as to surround the crankshaft 23. The third sensor 7 may detect the pedal force Tf (N) applied to the pedal 4, for example, by detecting the strain of the crankshaft 23 that is deformed due to the pedal force applied to the pedal 4, or may detect the pedal force Tf (N) using another sensor (for example, a magnetostrictive sensor).

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), that the third sensor 7 outputs a signal required 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 required to calculate the pedaling force Tf(N) to another arithmetic device (not shown), and the arithmetic device to which the signal is input calculates the pedaling force Tf(N) and outputs it to the control device 50. 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 on 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.

As shown in Fig. 2, the reducer 10 of the rotation device 70 includes an output gear 16, a clutch 33, and a group of other members 11. In this embodiment, the clutch 33 is a one-way clutch. The group of other members 11 is configured to transmit the rotational force of the output shaft 40S of the motor 40 to the output gear 16 at a certain reduction ratio, and may include, for example, a plurality of gears, a plurality of shafts, and a plurality of clutches (e.g., one-way clutches). Therefore, the reducer 10 has a predetermined reduction ratio gr _MDU resulting from the output gear 16 and the group of other members 11, and can decelerate the rotation of the motor 40 based on this reduction ratio gr _MDU .

In this embodiment, the output gear 16 has a cylindrical shape and includes a substantially annular gear 16a and a substantially cylindrical protrusion 16b that is arranged coaxially with the gear 16a. The crankshaft 23 passes through the space inside the output gear 16.

The gear 16a of the output gear 16 is fixed to the crankshaft 23 via the clutch 33. More specifically, the inner circumferential surface of the gear 16a (the circumferential surface on the side closer to the crankshaft 23) is fixed to the outer circumferential surface of the clutch 33 (the circumferential surface on the side farther from the crankshaft 23). Meanwhile, the outer circumferential surface of the gear 16a meshes with gears included in the other member group 11 of the reducer 10. The gear 16a is housed inside the housing 60.

The protrusion 16b of the output gear 16 is connected to the gear 16a, and protrudes from the gear 16a toward the other end 23b in the extension direction (axial or longitudinal direction) of the crankshaft 23. If necessary, the protrusion 16b may have an area with multiple teeth arranged in the circumferential direction (e.g., a gear) or an area with a spirally formed groove (e.g., a worm). A part of the protrusion 16b of the output gear 16 is outside the housing 60. A chain ring CR is fixed to the outer peripheral surface of the part of the protrusion 16b that is outside the housing 60.

The clutch 33 is configured to transmit rotation of the crankshaft 23 in one direction (forward direction) and not transmit rotation in the other direction (reverse direction). For example, when the pedal 4 is rotated in the reverse direction (the direction opposite to the direction in which the pedal 4 is rotated to move the electric-assisted bicycle 1 forward), the crankshaft 23 rotates in the reverse direction relative to the output gear 16. In this case, the metal members of the clutch 33 are disengaged, and the rotation of the crankshaft 23 is not transmitted to the output gear 16. That is, in this case, the rotation of the pedal 4 (rotation of the crankshaft 23) is not transmitted to the chain ring CR fixed to the output gear 16, preventing the rear wheel 3 from rotating in response to pedaling of the pedal 4. On the other hand, when the pedal 4 is rotated in the forward direction (the direction in which the pedal 4 is rotated to move the electric-assisted bicycle 1 forward), and the number of rotations of the pedal 4 (crankshaft 23) in the forward direction reaches a certain number of rotations, the metal members of the clutch 33 come into contact with each other, the crankshaft 23, the clutch 33, and the output gear 16 are connected, and the crankshaft 23 and the output gear 16 rotate together. In this way, the rotation of the crankshaft 23 is transmitted to the output gear 16. This causes the chain ring CR fixed to the output gear 16 to rotate, and the driving force is transmitted to the rear wheel 3 via the transmission body C that is stretched across the chain ring CR and the sprocket SP. In other words, when the number of rotations of the pedal 4 (crankshaft 23) in the forward direction reaches a certain number of rotations, the clutch 33 and the clutch of the other member group 11 enable the rotational force of the motor 40 to be transmitted to the rear wheel 3, and the force required to step on the pedal 4 is reduced (assisted) under a specified condition. On the other hand, when the pedal 4 (crankshaft 23) rotates in the relative reverse direction, the clutch 33 and the clutch of the other member group 11 prevent the assist of the motor 40 from being transmitted to the rear wheel 3. Note that "relative rotation in the reverse direction" may hereinafter be referred to simply as "rotation in the reverse direction."

Also, for example, when the speed change gear (not shown) of the sprocket SP is shifted from a heavy gear to a light gear, the output gear 16 may momentarily advance relative to the crankshaft 23 due to the rotational force assisted by the motor 40 immediately before, and the crankshaft 23 may momentarily rotate in the opposite direction relative to the output gear 16. Therefore, in this case, the metal members of the clutch 33 are in a disengaged state, and the rotation of the crankshaft 23 is not transmitted to the output gear 16. The crankshaft 23 then rotates in the forward direction. In this case, the metal members of the clutch 33 and the clutches of the other member group 11 come into contact with each other, connecting the crankshaft 23, the clutch 33, and the output gear 16, and the crankshaft 23 and the output gear 16 rotate together, and the rotation of the crankshaft 23 is transmitted to the output gear 16. In other words, the rotational force of the motor 40 can be transmitted to the rear wheel 3 via the output gear 16, and the force required to step on the pedal 4 is reduced (assisted) under certain conditions.

Also, as shown in FIG. 1, a clutch RC is provided on the axle of the rear wheel 3. This clutch RC may be a one-way clutch such as a ratchet. The clutch RC is configured to transmit the rotation of the sprocket SP rotating in the forward direction relative to the rotation direction of the rear wheel 3 to the rear wheel 3, and not transmit the rotation of the sprocket SP rotating in the reverse direction relative to the rotation direction of the rear wheel 3 to the rear wheel 3. Therefore, at the timing when the rotation of the sprocket SP rotating in the forward direction relative to the rotation direction of the rear wheel 3 is transmitted to the rear wheel 3, the metal members constituting the clutch RC on 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 C, and clutch RC of the rear wheel 3.

Also, for example, consider a case where the electrically assisted bicycle 1 travels downhill and then travels on flat ground or uphill. In this case, the rotation speed of the rear wheel 3 may be greater than the rotation speed of the sprocket SP transmitted from the rotation of the pedals 4 when traveling downhill, but even in such a case, when the road is flat or uphill, the rotation speed of the rear wheel 3 will eventually become the same as the rotation speed of the sprocket SP transmitted from the rotation of the pedals 4 (synchronize). In other words, after the rotation speed of the rear wheel 3 becomes greater than the rotation speed of the sprocket SP transmitted from the pedals 4, the rotation speed of the rear wheel 3 will become the same as the rotation speed of the sprocket SP transmitted from the pedals 4 (synchronize). In particular, when the electrically assisted bicycle 1 travels downhill, the sprocket SP will rotate in the opposite direction to the rear wheel 3, so the metal members of the clutch RC will be released and the force applied to the pedals 4 will no longer be transmitted to the rear wheel 3, so it is desirable to release the drive (assist) of the motor 40. On the other hand, when the electrically assisted bicycle 1 travels from a downhill slope to flat ground or uphill, and the rotation speed of the rear wheel 3 drops to the rotation speed of the sprocket SP, the metal members that make up the clutch RC come into contact with each other, and the rear wheel 3 and the sprocket SP rotate together. In other words, the rotational force of the driven motor 40 can be transmitted to the rear wheel 3, and the force applied to the pedals 4 required to rotate the rear wheel 3 is reduced (assisted) under certain conditions.

Next, the control device 50 will be described in detail. FIG. 3 is a block diagram showing the configuration of the control device 50, the first sensor 5, the second sensor 6, the third sensor 7, the fourth sensor 8, and the motor 40. As shown in FIG. 3, 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. 3 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 the functions and configurations shown in FIG. 3.

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.

As shown in FIG. 3, in this embodiment, the control circuit 50a 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 suppression unit 55, a judgment unit 56, a mode determination unit 57, a storage unit (memory) 58, and a drive signal generation unit 59. The storage unit 58 may be all or part of each storage device such as the RAM and ROM described above. The first calculation unit 51, the second calculation unit 52, the third calculation unit 53, the fourth calculation unit 54, the output suppression unit 55, the judgment unit 56, the mode determination unit 57, and the drive signal generation unit 59 are realized, for example, by a processor in a program processing device serving as the control circuit 50a, which executes various arithmetic processing according to the programs stored in each storage device described above, including the storage unit 58, and controls peripheral circuits such as a counter and an A/D conversion circuit.

In this embodiment, in addition to the above-mentioned programs, the memory unit 58 stores data on the reduction ratio gr _MDU of the reducer 10 (hereinafter, may be referred to as "reduction ratio data"), data indicating a range of the ratio R (hereinafter, may be referred to as "range data"), etc. Note that the control circuit 50a may have other functional blocks.

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 as described above, the second sensor 6 that detects the rotation speed Nm of the rotor of the motor 40 as described above, the third sensor 7 as a torque sensor as described above, and the fourth sensor 8 that detects the predetermined rotation angle An of the wheel as described above. The first calculation unit 51 calculates the rotation speed Nw (rpm) of the wheel and the vehicle speed Vb (km/h) based on the signal input from the first sensor 5. The second calculation unit 52 calculates the rotation speed Nm (rpm) of the motor 40 based on the signal input from the second sensor 6.

Incidentally, a sensor (typically a Hall sensor) that detects the rotation 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 rotation speed Np (rpm) of the pedal (crankshaft), so by calculating the rotation speed Np (rpm) of the pedal 4 using formula (B), data on the rotation speed Np (rpm) of the pedal 4 can be obtained with higher accuracy (for example, at a time interval that is desired to be used in the software). As a first case in which the rotation speed can be obtained more accurately using a sensor that detects the rotation speed Nm (rpm) of the motor 40, there is a case in which, in the case of a sensor that directly detects the rotation speed Np (rpm) of the pedal, the distance between the magnet on the shaft connecting both pedals 4 and the magnetic sensor changes slightly due to the effect of the shaft being distorted by the pedaling force. On the other hand, the sensor that detects the rotation speed Nm (rpm) of the motor 40 is fixed so that it is always in the same position relative to the rotor of the motor 40, so that the sensor that detects the rotation speed Nm (rpm) of the motor 40 can practically always obtain accurate magnetism. In the second case, there is the influence of the power of the rotating body to be detected. That is, in a sensor that detects the rotation speed Nm (rpm) of the motor 40, the power of the motor 40 of the rotating body to be detected is electricity, whereas in a sensor that directly detects the rotation speed Np (rpm) of the pedal, the power of the rotating body to be detected is human power. For example, if the detection cycle is set to 1 ms, the fluctuations per detection cycle are smaller with electricity than with human power, and this can be used as data in the software.

The third calculation unit 53 calculates the force Tf (N) applied to the pedal 4 based on the signal input from the third sensor 7, and further calculates the torque command value Tm (Nm), which is the 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.

The fourth sensor 8 outputs a signal Sa to the fourth calculation unit 54, which indicates that the wheel has rotated a predetermined rotation angle An (deg).

When the signal Sa is input to the fourth calculation unit 54, the fourth calculation unit 54 calculates a magnitude (note that this magnitude may be referred to as the ratio R of the wheel rotation speed to the motor rotation speed, or simply as the ratio _{R) obtained by the following formula (1) based on the wheel rotation speed Nw (rpm) calculated by the first calculation unit 51, the motor rotation speed Nm (rpm) calculated by the second calculation unit 52, and the reduction ratio data (data of the reduction ratio gr MDU} of the reducer 10) stored in the memory unit 58.
R=Nm/(Nw・gr _MDU )...(1)

The determination unit 56 reads out the above-mentioned range data from the storage unit 58 and determines whether the ratio R calculated by the fourth calculation unit 54 is within the predetermined range Ra. The predetermined range Ra of the ratio R, which is the range data, may be, for example, the reduction ratio gr _MDU of the reducer 10, and may be 0.736≦R≦0.900 or 0.225≦R≦0.275. The predetermined range Ra may be individually and specifically set based on the performance of the electric assisted bicycle (for example, the output of the motor, the reduction ratio of the reducer, the diameter of the wheels, etc.), and is not particularly limited. When the determination unit 56 determines that the ratio R is within the predetermined range Ra, it outputs the first signal S1 to the mode determination unit 57, and when the determination unit 56 determines that the ratio R is outside the predetermined range Ra, it outputs the second signal S2 to the mode determination unit 57. The range "within the predetermined range Ra" may be specified to include the upper limit value and the lower limit value of the range Ra, or may be specified to include either the upper limit value or the lower limit value. For the sake of convenience, in this specification, "within a predetermined range Ra" includes the upper limit and the lower limit.

For example, when signal Sa is input to fourth calculation unit 54 every time the wheel rotates 30° (i.e., when the specified rotation angle An (deg) is 30°), judgment unit 56 judges whether or not the ratio R calculated by fourth calculation unit 54 is within the specified range Ra 12 times per wheel rotation. Also, when signal Sa is input to fourth calculation unit 54 every time the wheel rotates 60° (i.e., when the specified rotation angle An (deg) is 60°), judgment unit 56 judges whether or not the ratio R calculated by fourth calculation unit 54 is within the specified range Ra 6 times per wheel rotation. Similarly, the determination unit 56 performs a determination four times per wheel rotation when the predetermined rotation angle An (deg) is 90°, performs a determination eight times per wheel rotation when the predetermined rotation angle An (deg) is 45°, performs a determination 24 times per wheel rotation when the predetermined rotation angle An (deg) is 15°, and performs a determination 36 times per wheel rotation when the predetermined rotation angle An (deg) is 10°. Also, the determination unit 56 performs a determination once per wheel rotation when the predetermined rotation angle An (deg) is 360°.

The mode determination unit 57 includes a counter 57C. This counter 57C is configured to output the third signal S3 to the output suppression unit 55 when the first signal S1 is input from the determination unit 56 to the counter 57C N or more times in succession. Here, N is a natural number equal to or greater than 1. That is, the mode determination unit 57 (counter 57C) outputs the third signal S3 to the output suppression unit 55 when the first signal S1 is input N times in succession, and also outputs the third signal S3 to the output suppression unit 55 when the first signal S1 is input (N+1), (N+2), ..., (N+n (n is a natural number equal to or greater than 1)) times in succession. On the other hand, the mode determination unit 57 outputs the fourth signal S4 to the output suppression unit 55 when the first signal S1 is not input to the mode determination unit 57 N or more times in succession, in other words, when the second signal S2 is input to the mode determination unit 57. As will be mentioned later, the mode determination unit 57 may reset the value of the counter 57C to zero when the fourth signal S4 is output, and may return the value of the counter 57C to N when the value of n reaches a predetermined value.

When the output suppression unit 55 receives the third signal S3 from the mode determination unit 57, it outputs a fifth signal S5 indicating the torque command value Tm (Nm) calculated by the third calculation unit 53 to the drive signal generation unit 59. The control mode in which the motor 40 is driven based on the torque command value Tm (Nm) is the normal output mode. On the other hand, when the output suppression unit 55 receives the fourth signal S4 from the mode determination unit 57, it outputs a sixth signal S6 indicating a torque command value (hereinafter, sometimes referred to as "reduced torque command value RTm (Nm)") obtained by suppressing the torque command value Tm (Nm) calculated by the third calculation unit 53 to the drive signal generation unit 59. The control mode in which the motor 40 is driven based on the reduced torque command value RTm (Nm) is the output reduced mode.

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

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

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, for example, when the motor 40 is a brushless DC motor having coils corresponding to the three phases (U phase, V phase, and W phase). The drive circuit 50b may have, 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.

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 the control circuit 50a and the drive circuit 50b are each packaged as separate integrated circuit devices.

Next, an example of steps in the control by the control device 50 will be described. FIG. 4 is a flow chart 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 St8. Hereinafter, among the steps in the control shown in FIG. 4, steps St2 to St8 may be referred to as the "mode decision flow MF."

In this embodiment, for example, when the drive of the motor 40 starts, the step of starting control may be started (START). Specifically, the step of starting control may be started at the timing when the drive signal generating unit 59 generates the drive signal Sd for driving the motor 40 and outputs it to the drive circuit 50b.

(Step St1)
When a signal Sa indicating that the wheel has rotated a predetermined rotation angle An (deg) is input to the fourth calculation unit 54, the control unit 50 advances the control step to step St2 and starts the mode decision flow MF (St2 to St8). On the other hand, when the signal Sa is not input to the fourth calculation unit 54, the control unit 50 returns to the step of starting the control and repeats the cycle of proceeding to step St1 until the signal Sa is input to the determination unit 56. 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.

(Step St2)
When the signal Sa is input to the fourth calculation unit 54, the control device 50 calculates the ratio R in the fourth calculation unit 54 based on the above-mentioned formula (1). Specifically, the fourth calculation unit 54 calculates the ratio R based on the wheel rotation speed Nw (rpm) calculated by the first calculation unit 51, the motor 40 rotation speed Nm (rpm) calculated by the second calculation unit 52, and the reduction ratio data (reduction ratio gr _MDU of the reducer 10) stored in the memory unit 58. When the fourth calculation unit 54 calculates the ratio R, the control device 50 advances the control step to step St3.

(Step St3)
The control device 50 refers to the range data stored in the memory unit 58, and in the determination unit 56, determines whether the ratio R calculated by the fourth calculation unit 54 is within the predetermined range Ra. When the control device 50 determines that the ratio R is outside the predetermined range Ra, the control proceeds to step St4. Specifically, the determination unit 56 outputs the second signal S2 to the mode determination unit 57, whereby the control proceeds to step St4. On the other hand, when the control device 50 determines that the ratio R is within the predetermined range Ra, the control proceeds to step St5.

(Step St4)
In this step, the control device 50 outputs the fourth signal S4 from the mode determination unit 57 to the output suppression unit 55. When the control device 50 outputs the fourth signal S4, if the value of the counter 57C of the mode determination unit 57 is greater than zero, the control device 50 may reset the value of the counter 57C to zero. When the fourth signal S4 is input to the output suppression unit 55, the control device 50 inputs a signal S6 indicating a suppression torque command value RTm (Nm) obtained by suppressing the torque command value Tm (Nm) calculated by the third calculation unit 53 to the drive signal generation unit 59. The control device 50 generates a drive signal Sd based on the suppression torque command value RTm (Nm) in the drive signal generation unit 59 and outputs the drive signal Sd to the drive circuit 50b. Then, the control device 50 controls the operation of the motor 40 based on the drive signal Sd of the suppression torque command value RTm (Nm) via the drive circuit 50b. In this way, the control device 50 turns on the output suppression mode. That is, by passing through this step, the motor 40 rotates with a torque smaller than that in the normal output mode, and as a result, the assist by the motor 40 is reduced compared to the normal output mode. Then, the control device 50 returns the step in the control to step St1.

(Step St5)
The control device 50, in the determination unit 56, outputs a first signal S1 to the mode determination unit 57. This first signal S1 is input to the counter 57C of the mode determination unit 57. That is, in this step, the control device 50, in the determination unit 56, outputs the first signal S1, which is a counter input signal, to the mode determination unit 57. Then, the control device 50 advances the control step to step St6.

(Steps St6 and St7)
In step St6, the control device 50 increments the counter 57C of the mode determination unit 57 by 1, and determines whether the first signal S1 has been input to the counter 57C N or more consecutive times. Note that "consecutive inputs to the counter 57C" refers to a case where, when the currently executed mode decision flow MF is the (m+1)th (m is a natural number) mode decision flow MF, the first signal S1 has also been input to the counter 57C in step St6 in the mth mode decision flow MF. This point will be described further below.

If, in step St6 of the m-th mode decision flow MF, the input of the first signal S1 to the counter 57C is not N or more consecutive inputs to the counter 57C, the control device 50 advances the step in the control to step St7. In step St7, the control device 50 turns on the output suppression mode as in step St4. This causes the motor 40 to rotate with a torque smaller than that in the normal output mode, and as a result, the assist by the motor 40 is reduced compared to the normal output mode. Then, the control device 50 returns the step in the control to step St1. If the signal Sa is input to the determination unit 56 in this returned step St1 (i.e., the (m+1)th step St1), the control device 50 executes the (m+1)th mode decision flow MF. In other words, if the signal Sa is not input to the determination unit 56, the control device 50 does not execute the (m+1)th mode decision flow MF, and repeats step St1 until the signal Sa is input to the determination unit 56. Therefore, in this embodiment, the mode decision flow MF is executed every time the wheel rotates An (deg) (e.g., 30°).

If the ratio R is outside the specified range Ra in step St3 of the (m+1)th mode decision flow MF or the input of the first signal S1 (counter input signal) in step St6 of the (m+1)th mode decision flow MF is not an input for N or more consecutive times, and if the output suppression mode is selected in the mth mode decision flow MF, the control device 50 maintains the output suppression mode in the (m+1)th mode decision flow MF; on the other hand, if the output mode is selected in the mth mode decision flow MF, the control device 50 switches to the output suppression mode in the (m+1)th mode decision flow MF. Here, if the mth mode decision flow MF was in normal output mode, the (m+1)th mode decision flow MF switches to output suppression mode, and then, even if step St6 is reached in the (m+2)th mode decision flow MF, the input of the first signal S1 (counter input signal) to the counter 57C in the (m+2)th mode decision flow MF does not result in a continuous input of the first signal S1 (counter input signal) to the counter 57C. In such a case, the control device 50 resets the value of the counter 57C to zero in step St6 in the (m+2)th mode decision flow MF.

On the other hand, if the counter 57C reaches step St6 in the mth mode decision flow MF and the first signal S1 has not been input to the counter 57C N times or more consecutively in the mth mode decision flow MF, then when the counter 57C reaches step St6 in the (m+1)th mode decision flow MF, the counter 57C is further incremented (accumulated). Here, for example, consider the case where m is 1 (i.e., the first mode decision flow MF). When the first (mth) mode decision flow MF reaches step St6, the counter 57C is incremented by 1 and the value of the counter 57C becomes 1. Next, when the counter 57C reaches step St6 in the second ((m+1)th) mode decision flow MF, the counter 57C is incremented (accumulated) by 1 and the value of the counter 57C becomes 2. Here, for example, if the value of N is 4 (times), the value of the counter 57C in the second ((m+1)th) mode decision flow MF is 2, which is smaller than 4. That is, in this case, the first signal S1 has not been input to the counter 57C four (N) times in succession in the second ((m+1)) mode decision flow MF. Therefore, the control device 50 returns to step St1 via steps St6 and St7 of the second ((m+1)) mode decision flow MF, and executes the third ((m+2)) mode decision flow MF. Then, if step St6 is reached in each of the third mode decision flow MF and the fourth ((m+3)) mode decision flow MF, the value of the counter 57C is accumulated to 4 in the fourth ((m+3)) mode decision flow MF, so that the condition of four (N) times or more is met. Therefore, in this case, the control device 50 advances the step in the control to step St8.

(Step St8)
In this step, the control device 50 outputs the third signal S3 from the counter 57C to the output suppression unit 55. Then, the control device 50 outputs the fifth signal S5 indicating the torque command value Tm (Nm) from the output suppression unit 55 to the drive signal generation unit 59. Thus, in this step, the normal output mode is turned ON. Then, the control device 50 returns the control step to step St1.

However, if the ratio R is continuously within the predetermined range Ra in the subsequent cycles of steps in the control, the value of counter 57C is sequentially accumulated, and the value of counter 57C increases. Therefore, in order to prevent this, an upper limit may be set for the value of counter 57C, and when the value of counter 57C reaches the upper limit in step St6 of a step in a certain control, the value of counter 57C may be reset to N.

In this way, in the steps of the control shown in FIG. 4, the control device 50 makes the magnitude of assisting the rotation of the pedal 4 (torque of the motor 40 (torque command value Tm (Nm))) when the ratio R is within the predetermined range Ra (normal output mode) when the first signal S1 is input N or more times in succession, greater than the magnitude of assisting the rotation of the pedal 4 (torque of the motor 40 (restricted torque command value Rtm (Nm)))) when the ratio R is outside the predetermined range Ra (output suppression mode). In other words, in the steps of the control shown in FIG. 4, the control device 50 determines that "the ratio R is within the predetermined range Ra" when the first signal S1 (counter input signal) is input N or more times in succession and the ratio R is within the predetermined range Ra, and executes the normal output mode. The electrically assisted bicycle 1 is configured to make the torque of the motor 40 when the ratio R is outside the predetermined range Ra smaller than the torque of the motor 40 when the ratio R is within the predetermined range Ra.

As described above, when the crankshaft 23 transitions from a state in which it rotates in the reverse direction relative to the output gear 16 to a state in which it rotates in the forward direction in synchronization with the output gear 16, the metal members of the clutches (e.g., the clutch 33, the clutch of the other member group 11, and the clutch provided on the axle of the rear wheel 3) come into contact with each other, and the crankshaft 23, the clutch 33, the output gear 16, the clutch of the other member group 11, and the clutch provided on the axle of the rear wheel 3 are connected, making it possible to transmit the rotational force of the motor 40. Therefore, when the crankshaft 23 and the rear wheel 3 transition from a state in which they rotate in the reverse direction to a state in which they rotate in the forward direction in synchronization with the output gear 16, the rotational force of the motor 40 suddenly connects multiple metal members included in the MDU 100 (e.g., metal members included in various clutches such as the clutch 33) and may produce metallic noise.

As a result of the inventors' intensive research into this point, they found that when the crankshaft 23 and the rear wheel 3 transition from a state in which they rotate in the reverse direction to a state in which they rotate in the forward direction in synchronization with the output gear 16, the time-dependent change in the ratio R obtained from the above formula (1) becomes unstable. Specifically, they found that the ratio R tends to deviate from a predetermined range Ra during a predetermined time range when the crankshaft 23 and the rear wheel 3 transition from a state in which they rotate in the reverse direction to a state in which they rotate in the forward direction in synchronization with the output gear 16. In other words, when the ratio R is outside the predetermined range Ra, this is the timing when the crankshaft 23 and the rear wheel 3 transition from a state in which they rotate in the reverse direction to a state in which they rotate in the forward direction in synchronization with the output gear 16, and this is the timing at which the metallic sound described above occurs.

As described above, the control device 50 according to this embodiment increases the magnitude of assistance for the rotation of the pedal 4 when the ratio R is within the specified range Ra compared to the magnitude of assistance for the rotation of the pedal 4 when the ratio R is outside the specified range Ra. Also, in the electrically power assisted bicycle 1 according to this embodiment, the torque of the motor 40 outside the specified range Ra is smaller than the torque of the motor 40 within the specified range Ra. With this configuration, the rotational force of the motor 40 is suppressed when the metal members are connected, preventing the metal members from suddenly connecting to each other, and as a result, the occurrence of abnormal noises such as the metallic sounds described above in the electrically power assisted bicycle 1 is suppressed.

As described above, the control device 50 according to this embodiment determines that the ratio R is within the predetermined range Ra when the first signal S1 (counter input signal) is input N or more times in succession and the ratio R is within the predetermined range Ra, and executes the normal output mode. In other words, the control device 50 according to this embodiment executes the normal output mode when the ratio R becomes stable and falls within the predetermined range Ra, that is, when it is more accurately determined that metallic sounds are unlikely to occur. Therefore, the control device 50 and electrically assisted bicycle 1 according to this embodiment can better suppress the occurrence of abnormal sounds such as metallic sounds.

The present invention has been described above using the above embodiment as an example, but the present invention is not limited to this.

For example, in the above embodiment, an example was described in which the amount of assistance for the rotation of the pedal 4 was adjusted based on the torque command value (torque of the motor 40). However, instead of the torque command value, the amount of assistance for the rotation of the pedal 4 may be adjusted using the motor rotation speed as a command value.

In the above embodiment, the control device 50 determines that "the ratio R is within the predetermined range Ra" when the ratio R is within the predetermined range Ra each time the first signal S1 is input N or more times in succession, and executes the normal output mode. However, it may be configured to determine that "the ratio R is within the predetermined range Ra" when the ratio R is within the predetermined range Ra when the first signal S1 is first input to the control device 50, and execute the normal output mode. That is, in this case, for example, there is no need to provide a counter 57C in the mode determination unit 57, step St6 can be omitted, and there is no need to repeat the mode determination flow MF.

The present invention has been described above using the above-mentioned embodiment as an example, but the present invention is not limited to this, and a person skilled in the art can modify the control device and electrically assisted bicycle of the present invention as appropriate in accordance with conventional knowledge. As long as the configuration of the present invention is still included even after such modifications, it will of course be included in the scope of the present invention.

1...electrically assisted bicycle, 2...front wheel (wheel), 3...rear wheel (wheel), 4...pedal, 10...reduction gear, 40...motor, 50...control device, 70...rotation device, R...ratio (size), Ra...predetermined range

Claims (3)

A control device that increases the amount of assistance for pedal rotation when the ratio of the rotation speed of the wheel to the rotation speed of the motor is within a specified range, compared to the amount of assistance for pedal rotation when the ratio of the rotation speed of the wheel to the rotation speed of the motor is outside the specified range. The control device according to claim 1 ;
a rotation device having the motor and a reducer;
The pedal;
The wheel;
Equipped with
When the pedal is assisted by the rotation device,
An electrically assisted bicycle, wherein the magnitude of the following equation (1) is within a predetermined range, where 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 rotating device.
Nm/(Nw・gr _MDU )...(1) The electrically assisted bicycle according to claim 2, wherein the magnitude of the torque of the motor outside the predetermined range is smaller than the magnitude of the torque of the motor within the predetermined range.