Control device and electrically assisted bicycle

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

[0001] The present invention relates to a control device and an electrically assisted bicycle.

[0002] A control device is known 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, as well as an electrically assisted bicycle equipped with such a control device (see, for example, Patent Document 1).

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

[0004] In an electrically assisted bicycle, typically, 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 a control device.

[0005] When the clutch is not transmitting the driving force of the motor drive unit to the crankshaft, for example, if the pedals are pressed in the direction of accelerating the electrically assisted bicycle, the clutch will transition 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 the pedals hard to move the electrically assisted bicycle from a stop, metal parts such as the clutch may suddenly come into contact, and this sudden contact may cause an abnormal noise such as a metallic sound.

[0006] Therefore, one of the objects of the present invention is to provide a control device that can suppress the generation of abnormal noise in an electrically assisted bicycle, and an electrically assisted bicycle that can suppress the generation of abnormal noise.

[0007] The control device of the present invention increases the magnitude of assistance for pedal rotation when the ratio of the wheel rotation speed to the motor rotation speed is within a predetermined range compared to the magnitude of assistance for pedal rotation when the ratio of the wheel rotation speed to the motor rotation speed is outside the predetermined range.

[0008] Furthermore, an electrically assisted bicycle according to the present invention includes the above-described control device, a rotation device having the motor and the reducer, the pedals, and the wheel, and when the pedals are assisted by the rotation device, 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, the magnitude of the following equation (1) is within a predetermined range. ＭＤＵ ) ... (1)

[0009] In the above-described electrically assisted bicycle, the magnitude of the torque of the motor outside the predetermined range may be smaller than the magnitude of the torque of the motor within the predetermined range.

[0010] It is a side view showing an example of an electrically assisted bicycle according to an embodiment of the present invention. It is a diagram showing a schematic configuration of a rotating device provided in the electrically assisted bicycle shown in Fig. 1. It is a block diagram showing the configuration of a control device, sensors, and motor provided in the electrically assisted bicycle shown in Fig. 1. It 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.

[0011] Below, embodiments for implementing a control device and 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.

[0012] FIG. 1 is a side view of 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 mounted between the chain ring CR and the sprocket SP. The MDU 100 includes a motor 40 and a control device 50 that controls the operation of the motor 40 to provide power 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, 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 under certain conditions, enabling forward travel. At this time, under predetermined conditions, the motor 40 of the MDU 100 rotates under the control of the control device 50, and the rotation of the motor 40 provides assistance to reduce (assist) the force exerted by the driver on the pedals 4. The transmission body C may be a chain or a belt.

[0013] 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 vehicle speed Vb (km / h)" may mean that the first sensor 5 itself calculates the wheel rotation speed Nw (rpm) and vehicle speed Vb (km / h), that the first sensor 5 outputs signals necessary for calculating the wheel rotation speed Nw (rpm) and vehicle speed Vb (km / h) to the control device 50, and the control device 50 calculates the wheel rotation speed Nw (rpm) and vehicle speed Vb (km / h), or that the first sensor 5 outputs signals necessary for calculating the wheel rotation speed Nw (rpm) and vehicle speed Vb (km / h) to another calculation device (not shown), and the calculation device that receives the output signals calculates the wheel rotation speed Nw (rpm) and 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 capable of outputting signals necessary 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 anywhere that allows it to detect the wheel rotation speed Nw (rpm) and the vehicle speed Vb (km / h), and may be located, for example, away from the rotation axis of the front wheel 2 or the rear wheel 3.

[0014] Similarly, a fourth sensor 8 for detecting a predetermined rotation angle An (deg) of the wheel is disposed near the rotation axis of the front wheel 2 or the rear wheel 3. In this specification, "detecting the predetermined rotation angle An (deg) of the wheel" may mean that the fourth sensor 8 itself calculates the predetermined rotation angle An (deg), that the fourth sensor 8 outputs a signal required to calculate the predetermined rotation angle An (deg) of the wheel to the control device 50, and the control device 50 calculates the predetermined rotation angle An (deg), or that the fourth sensor 8 outputs a signal required to calculate the predetermined rotation angle An (deg) of the wheel to another calculation device (not shown), and the calculation device that receives the output signal calculates the predetermined rotation angle An (deg) of the wheel and outputs it to the control device 50. FIG. 1 shows an example in which the fourth sensor 8 is disposed near the rotation axis of the rear wheel 3. The fourth sensor 8 may be a known sensor capable of detecting the predetermined rotation angle An (deg) of the wheel or capable of outputting a signal necessary to calculate the predetermined rotation angle An (deg). The fourth sensor 8 may be, for example, a magnetic sensor or a Hall sensor capable of detecting the predetermined rotation angle An (deg), or an optical sensor capable of detecting the predetermined rotation angle An (deg). The fourth sensor 8 may be located at any position where it can detect the predetermined rotation angle An (deg), and may be located, for example, at a position away from the rotation axis of the front wheel 2 or the rear wheel 3.

[0015] In this embodiment, the fourth sensor 8 outputs a signal Sa to 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 control device 50. The predetermined rotation angle An (deg) is not particularly limited, and may be, for example, 30°, 120°, 90°, 60°, 45°, 15°, 10°, or any predetermined angle selected within the range of 1° to 360°.

[0016] The fourth sensor 8 and the first sensor 5 may be a common sensor.

[0017] The MDU 100 and the battery B are typically arranged around a crankshaft 23 connected to the pedals 4. FIG.

[0018] As shown in Figures 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, 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 Figure 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. A battery B supplies power to the motor 40 and control device 50, which operate using this power.

[0019] 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 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 (to pedal 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).

[0020] 2 , a second sensor 6 is disposed on 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. 2 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.

[0021] As shown in FIG. 2 , the crankshaft 23 passes through the housing 60 of the MDU 100. In the direction in which the crankshaft 23 extends (axial or longitudinal direction), the crankshaft 23 has one end 23 a and the other end 23 b. The one end 23 a and the other end 23 b are located outside the housing 60, and pedals 4 are fixed to the one end 23 a and the other end 23 b, respectively. When the pedals 4 are pedaled and rotated, the crankshaft 23 rotates. Note that FIG. 1 is a view of the electrically assisted bicycle 1 as viewed in the direction in which the crankshaft 23 extends (axial or longitudinal direction). The third sensor 7 described above is housed inside the housing 60 and may be attached, for example, 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 distortion of the crankshaft 23 that has been 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).

[0022] 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.

[0023] 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, multiple gears, multiple shafts, and multiple clutches (e.g., one-way clutches). Therefore, the reducer 10 transmits a predetermined reduction ratio gr generated by the output gear 16 and the group of other members 11. ＭＤＵ and this reduction ratio gr ＭＤＵ The rotation of the motor 40 can be decelerated based on the above.

[0024] In this embodiment, the output gear 16 has a cylindrical shape and includes a substantially annular gear 16 a and a substantially cylindrical protrusion 16 b that is provided coaxially with the gear 16 a. The crankshaft 23 passes through the space inside the output gear 16.

[0025] 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). On the other hand, the outer circumferential surface of the gear 16a meshes with gears included in the group of other members 11 of the reducer 10. The gear 16a is accommodated inside the housing 60.

[0026] The protruding portion 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 protruding portion 16b may have a region with multiple teeth arranged in the circumferential direction (e.g., a gear) or a region with a spiral groove (e.g., a worm). A portion of the protruding portion 16b of the output gear 16 is located outside the housing 60. A chain ring CR is fixed to the outer peripheral surface of the portion of the protruding portion 16b that is located outside the housing 60.

[0027] The clutch 33 is configured to transmit rotation of the crankshaft 23 in one direction (forward direction) but not transmit rotation in the other direction (reverse direction). 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 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. In other words, in this case, the rotation of the pedals 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 pedals 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 electrically assisted bicycle 1 forward), and the rotation speed of the pedal 4 (crankshaft 23) in the forward direction reaches a certain rotation speed, the metal members of the clutch 33 come into contact with each other, connecting the crankshaft 23, clutch 33, and output gear 16, and the crankshaft 23 and output gear 16 to rotate integrally. Thus, the rotation of the crankshaft 23 is transmitted to the output gear 16. This in turn rotates the chain ring CR fixed to the output gear 16, and driving force is transmitted to the rear wheel 3 via the transmission body C that is stretched between the chain ring CR and the sprocket SP. In other words, when the rotation speed of the pedal 4 (crankshaft 23) in the forward direction reaches a certain rotation speed, the clutch 33 and the clutches 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 press the pedal 4 is reduced (assisted) under predetermined conditions. 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 simply referred to as "rotation in the reverse direction."

[0028] Furthermore, for example, when the transmission gear (not shown) of the sprocket SP is shifted from a heavier gear to a lighter gear, the rotational force assisted by the motor 40 up until that point may momentarily cause the output gear 16 to advance relative to the crankshaft 23, and the crankshaft 23 to momentarily rotate in the opposite direction relative to the output gear 16. Therefore, 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. The crankshaft 23 then rotates forward. 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. The crankshaft 23 and the output gear 16 rotate integrally, 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 depress the pedals 4 is reduced (assisted) under certain conditions.

[0029] 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 a forward direction relative to the rotational direction of the rear wheel 3 to the rear wheel 3, but not to transmit the rotation of the sprocket SP rotating in a reverse direction relative to the rotational 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 rotational 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. As a result, the rotational force of the pedals 4 and the rotational force of the motor 40 are transmitted to the rear wheel 3 via the chain ring CR, the sprocket SP, the transmission body C, and the clutch RC of the rear wheel 3.

[0030] Consider, for example, a case in which 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. Even in such a case, once the bicycle reaches flat ground or an uphill slope, the rotation speed of the rear wheel 3 eventually becomes equal to (synchronizes with) the rotation speed of the sprocket SP transmitted from the rotation of the pedals 4. That is, 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 becomes equal to (synchronizes with) the rotation speed of the sprocket SP transmitted from the pedals 4. In particular, when the electrically assisted bicycle 1 is traveling downhill, the sprocket SP rotates in the opposite direction to the rear wheel 3, causing the metal members of the clutch RC to disengage. This prevents the pedal force applied to the pedals 4 from being transmitted to the rear wheel 3, and therefore desirably disengages 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 an uphill slope 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, causing the rear wheel 3 and sprocket SP to 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.

[0031] 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 those shown in FIG. 3.

[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] 3 , 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 suppression unit 55, a determination 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 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 output suppression unit 55, the determination unit 56, the mode determination unit 57, 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 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.

[0034] 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, this may be referred to as "reduction ratio data"), and data indicating the range of the ratio R (hereinafter, this may be referred to as "range data"), which will be described later. The control circuit 50a may have other functional blocks.

[0035] The control circuit 50a receives signals output from the first sensor 5 that detects the wheel rotation speed Nw and the vehicle speed Vb of the electrically assisted bicycle 1, the second sensor 6 that detects the rotor rotation speed Nm of the motor 40, the third sensor 7 that serves as the torque sensor, and the fourth sensor 8 that detects the predetermined wheel rotation angle An. The first calculation unit 51 calculates the wheel rotation speed Nw (rpm) and the vehicle speed Vb (km / h) based on the signal input from the first sensor 5. The second calculation unit 52 calculates the motor 40 rotation speed Nm (rpm) based on the signal input from the second sensor 6.

[0036] 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.

[0037] 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, 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.

[0038] 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).

[0039] When the signal Sa is input to the fourth calculation unit 54, the fourth calculation unit 54 calculates the number of rotations Nw (rpm) of the wheel calculated by the first calculation unit 51, the number of rotations Nm (rpm) of the motor 40 calculated by the second calculation unit 52, and the reduction ratio data (reduction ratio gr of the reducer 10) stored in the memory unit 58. ＭＤＵ Based on the data, the magnitude obtained by the following formula (1) (note that this magnitude may be referred to as the ratio R between the rotation speed of the wheel and the rotation speed of the motor, or simply as the ratio R) is calculated: R = Nm / (Nw·gr ＭＤＵ ) ... (1)

[0040] The determination unit 56 reads the range data from the storage unit 58 and determines whether the ratio R calculated by the fourth calculation unit 54 is within a predetermined range Ra. The predetermined range Ra of the ratio R, which is the range data, is, for example, the reduction ratio gr of the reducer 10. ＭＤＵ Examples of the predetermined range Ra include 0.736≦R≦0.900, and 0.225≦R≦0.275. The predetermined range Ra may be individually and specifically set based on the performance of the electrically assisted bicycle (e.g., motor output, reduction ratio of the reducer, wheel diameter, etc.), and is not particularly limited. When the determination unit 56 determines that the ratio R is within the predetermined range Ra, it outputs a first signal S1 to the mode determination unit 57. When the determination unit 56 determines that the ratio R is outside the predetermined range Ra, it outputs a second signal S2 to the mode determination unit 57. The range "within the predetermined range Ra" may be defined as including the upper and lower limits of the range Ra, or may be defined as including either the upper or lower limit. For convenience, in this specification, "within the predetermined range Ra" is defined as including the upper and lower limits.

[0041] For example, if the signal Sa is input to the fourth calculation unit 54 every time the wheel rotates 30° (i.e., the predetermined rotation angle An (deg) is 30°), the determination unit 56 determines whether the ratio R calculated by the fourth calculation unit 54 is within the predetermined range Ra, 12 times per wheel rotation. Also, if the signal Sa is input to the fourth calculation unit 54 every time the wheel rotates 60° (i.e., the predetermined rotation angle An (deg) is 60°), the determination unit 56 determines whether the ratio R calculated by the fourth calculation unit 54 is within the predetermined range Ra, 6 times per wheel rotation. Similarly, the determination unit 56 performs the determination four times per wheel rotation when the predetermined rotation angle An (deg) is 90°, performs the determination eight times per wheel rotation when the predetermined rotation angle An (deg) is 45°, performs the determination 24 times per wheel rotation when the predetermined rotation angle An (deg) is 15°, and performs the determination 36 times per wheel rotation when the predetermined rotation angle An (deg) is 10°. Furthermore, the determination unit 56 performs the determination once per wheel rotation when the predetermined rotation angle An (deg) is 360°.

[0042] The mode determination unit 57 includes a counter 57C. This counter 57C is configured to output a third signal S3 to the output suppression unit 55 when the first signal S1 is input from the determination unit 56 to the counter 57C N or more consecutive times, where N is a natural number greater than or equal to 1. That is, the mode determination unit 57 (counter 57C) outputs the third signal S3 to the output suppression unit 55 when the first signal S1 is input N or more consecutive times, 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 greater than or equal to 1)) or more consecutive times. On the other hand, the mode determination unit 57 outputs a fourth signal S4 to the output suppression unit 55 when the first signal S1 is not input N or more consecutive times to the mode determination unit 57, in other words, when the second signal S2 is input to the mode determination unit 57. As will be mentioned again later, the mode determination unit 57 may reset the value of the counter 57C to zero when it outputs the fourth signal S4, or may return the value of the counter 57C to N when the value of n reaches a predetermined value.

[0043] When the third signal S3 is input from the mode determination unit 57, the output suppression unit 55 outputs a fifth signal S5 indicating the torque command value Tm (Nm) calculated by the third calculation unit 53 to the drive signal generation unit 59. The control mode in which the motor 40 is driven based on the torque command value Tm (Nm) is the normal output mode. On the other hand, when the fourth signal S4 is input from the mode determination unit 57, the output suppression unit 55 outputs a sixth signal S6 indicating a torque command value (hereinafter, sometimes referred to as a "reduced torque command value RTm (Nm)") obtained by suppressing the torque command value Tm (Nm) calculated by the third calculation unit 53 to the drive signal generation unit 59. The control mode in which the motor 40 is driven based on the reduced torque command value RTm (Nm) is the output reduced mode.

[0044] Here, the suppression torque command value RTm (Nm) for the output suppression mode is smaller than the torque command value Tm (Nm) for the normal output mode, and may be, for example, the torque obtained by multiplying the smallest torque (Nm) of motor 40 in the normal output mode by a number M (0<M<1) that is smaller than 1. In other words, in electrically assisted bicycle 1, the suppression torque command value RTm (Nm) of motor 40 when ratio R is outside predetermined range Ra is smaller than the torque command value Tm (Nm) of motor 40 when ratio R is within predetermined range Ra each time the first signal S1 is input N or more consecutive times.

[0045] The drive signal generation unit 59 generates a drive signal Sd for driving the motor 40 and outputs it to the drive circuit 50b. Specifically, when the fifth signal S5 is input, the drive signal generation unit 59 outputs a drive signal Sd for causing the motor 40 to exert a torque of the torque command value Tm (Nm) indicated by the fifth signal S5 to the drive circuit 50b, and when the sixth signal S6 is input, the drive signal generation unit 59 outputs a drive signal Sd for causing the motor 40 to exert a torque of the suppression torque command value RTm (Nm) indicated by the sixth signal S6 to the drive circuit 50b. The drive signal Sd is, for example, a PWM (Pulse Width Modulation) signal.

[0046] 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.

[0047] 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.

[0048] 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 St8. Hereinafter, among the steps in the control shown in FIG. 4, steps St2 to St8 may be referred to as a "mode determination flow MF."

[0049] In the present embodiment, for example, the step of starting control may be started (START) when the driving of the motor 40 is started. Specifically, the step of starting control may be started at the timing when the driving signal generating unit 59 generates the driving signal Sd for driving the motor 40 and outputs it to the driving circuit 50b.

[0050] (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 determination 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 advancing 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.

[0051] (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 number of rotations Nw (rpm) of the wheel calculated by the first calculation unit 51, the number of rotations Nm (rpm) of the motor 40 calculated by the second calculation unit 52, and the reduction ratio data (reduction ratio gr of the reducer 10) stored in the memory unit 58. ＭＤＵ When the fourth calculation unit 54 calculates the ratio R, the control device 50 advances the control to step St3.

[0052] (Step St3) The control device 50 refers to the range data stored in the memory unit 58, and causes the determination unit 56 to determine whether the ratio R calculated by the fourth calculation unit 54 is within the predetermined range Ra. If 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, causing the control to proceed to step St4. On the other hand, if the control device 50 determines that the ratio R is within the predetermined range Ra, the control proceeds to step St5.

[0053] (Step St4) In this step, the control device 50 outputs a fourth signal S4 from the mode determination unit 57 to the output suppression unit 55. Note that, when the control device 50 outputs the fourth signal S4, if the value of the counter 57C of the mode determination unit 57 is greater than zero, the control device 50 may reset the value of the counter 57C to zero. When the fourth signal S4 is input to the output suppression unit 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 this drive signal Sd to the drive circuit 50b. The control device 50 then controls the operation of the motor 40 based on the drive signal Sd of the suppression torque command value RTm (Nm) via the drive circuit 50b. In this way, the control device 50 turns on the output suppression mode. That is, by going through this step, the motor 40 rotates with a torque smaller than in the normal output mode, and as a result, the assist by the motor 40 is reduced compared to the normal output mode. Then, the control device 50 returns the step in the control to step St1.

[0054] (Step St5) The control device 50 causes the determination unit 56 to output a first signal S1 to the mode determination unit 57. This first signal S1 is input to the counter 57C of the mode determination unit 57. That is, in this step, the control device 50 causes the determination unit 56 to output the first signal S1, which is a counter input signal, to the mode determination unit 57. Then, the control device 50 advances the control step to step St6.

[0055] (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 the case where, when the currently executed mode determination flow MF is the (m+1)th (m is a natural number) mode determination flow MF, the first signal S1 has also been input to the counter 57C in step St6 of the mth mode determination flow MF. This point will be described further below.

[0056] In step St6 of the mth mode determination flow MF, if the first signal S1 has not been input to the counter 57C N or more consecutive times, the control device 50 proceeds to step St7. In step St7, the control device 50 turns on the output reduction mode, as in step St4. This causes the motor 40 to rotate with a torque smaller than in the normal output mode, resulting in reduced assistance by the motor 40 compared to the normal output mode. The control device 50 then returns the control to step St1. 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 determination flow MF. Conversely, if the signal Sa is not input to the determination unit 56, the control device 50 does not execute the (m+1)th mode determination flow MF, and repeats step St1 until the signal Sa is input to the determination unit 56. Therefore, in this embodiment, the mode determination flow MF is executed every time the wheel rotates An (deg) (for example, 30°).

[0057] If the ratio R is outside the predetermined range Ra in step St3 of the (m+1)th mode decision flow MF, or if the input of the first signal S1 (counter input signal) in step St6 of the (m+1)th mode decision flow MF is not N or more consecutive inputs, and if the output reduction mode was selected in the mth mode decision flow MF, the control device 50 maintains the output reduction mode in the (m+1)th mode decision flow MF; on the other hand, if the output mode was selected in the mth mode decision flow MF, the control device 50 switches to the output reduction mode in the (m+1)th mode decision flow MF. Here, if the normal output mode was selected in the mth mode decision flow MF, the (m+1)th mode decision flow MF switches to the reduced output mode, and then step 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.

[0058] 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 or more consecutive times in the mth mode decision flow MF, and if the counter 57C reaches step St6 in the (m+1)th mode decision flow MF, the counter 57C is further incremented (incremented) by 1. Consider, for example, the case where m is 1 (i.e., the first mode decision flow MF). When the counter 57C reaches step St6 in the first (mth) mode decision flow MF, the counter 57C is incremented by 1, and the value of the counter 57C becomes 1. Next, when the counter 57C reaches step St6 in the second ((m+1)th) mode decision flow MF, the counter 57C is incremented by 1, and the value of the counter 57C becomes 2. If, for example, 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 or more times (N times) consecutively 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. If step St6 is reached in both the third mode decision flow MF and the fourth ((m+3)) mode decision flow MF, the value of the counter 57C is incremented to 4 in the fourth ((m+3)) mode decision flow MF, satisfying the condition of four or more times (N times). Therefore, in this case, the control device 50 advances the control to step St8.

[0059] (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.

[0060] Meanwhile, if the ratio R is continuously within the predetermined range Ra in the subsequent cycles of steps in the control, the value of the counter 57C is sequentially accumulated and increases. Therefore, to prevent this, an upper limit may be set for the value of the counter 57C, and when the value of the counter 57C reaches the upper limit in step St6 of a step in a certain control, the value of the counter 57C may be reset to N.

[0061] Thus, in the steps of the control shown in FIG. 4 , the control device 50 increases the magnitude of assistance for 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) each time the first signal S1 is input N or more consecutive times, compared to the magnitude of assistance for the rotation of the pedal 4 (torque of the motor 40 (reduced torque command value Rtm (Nm))) when the ratio R is outside the predetermined range Ra (output reduced 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 consecutive times, and executes the normal output mode. The electrically assisted bicycle 1 is configured to reduce the torque of the motor 40 when the ratio R is outside the predetermined range Ra compared to the torque of the motor 40 when the ratio R is within the predetermined range Ra.

[0062] 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 clutches 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 clutches of the other member group 11, and the clutch provided on the axle of the rear wheel 3 are coupled together, thereby enabling the transmission of 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 couples together multiple metal members included in the MDU 100 (e.g., metal members included in various clutches such as the clutch 33), which may result in metallic noise.

[0063] As a result of extensive research into this point, the inventors have found that the time-dependent change in the ratio R obtained from the above formula (1) becomes unstable when the crankshaft 23 or the rear wheel 3 transitions 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. Specifically, the inventors have found that the ratio R tends to deviate from a predetermined range Ra within a predetermined time range when the crankshaft 23 or the rear wheel 3 transitions 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 or the rear wheel 3 transitions 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 noise described above occurs.

[0064] As described above, the control device 50 according to this embodiment increases the magnitude of assistance provided to the rotation of the pedal 4 when the ratio R is within the predetermined range Ra compared to the magnitude of assistance provided to the rotation of the pedal 4 when the ratio R is outside the predetermined range Ra. Also, in the electrically power assisted bicycle 1 according to this embodiment, the torque of the motor 40 outside the predetermined range Ra is smaller than the torque of the motor 40 within the predetermined 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, thereby preventing the occurrence of abnormal noises such as the metallic sounds described above in the electrically power assisted bicycle 1.

[0065] Furthermore, as described above, the control device 50 according to this embodiment 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 (counter input signal) is input N or more consecutive times, and executes the normal output mode. That is, 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 further suppress the generation of abnormal noises such as metallic sounds.

[0066] Although the present invention has been described above using the above embodiment as an example, the present invention is not limited to this.

[0067] For example, in the above embodiment, an example was described in which the magnitude of assistance in 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 magnitude of assistance in the rotation of the pedal 4 may be adjusted using the motor rotation speed as a command value.

[0068] 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 consecutively N or more times, and executes the normal output mode. However, the control device 50 may 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 the counter 57C in the mode determination unit 57, and step St6 can be omitted, and there is no need to repeat the mode determination flow MF.

[0069] While the present invention has been described above using the above-mentioned embodiment as an example, the present invention is not limited to this, and those skilled in the art can appropriately modify the control device and electrically assisted bicycle of the present invention 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.

[0070] 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 (magnitude), Ra...predetermined range

Claims

1. A control device that makes the magnitude of assisting the rotation of the pedal when the ratio of the rotational speed of the wheel to the rotational speed of the motor is within a predetermined range greater than the magnitude of assisting the rotation of the pedal when the ratio of the rotational speed of the wheel to the rotational speed of the motor is outside the predetermined range.

2. A control device according to claim 1, a rotating device having the motor and a speed reducer, the pedal, and the wheel, wherein when the pedal is assisted by the rotating device, Nw is the rotational speed (rpm) of the wheel, Nm is the rotational speed (rpm) of the motor, and gr ＭＤＵ is the reduction ratio of the rotating device, and an electric assist bicycle in which the magnitude of the following formula (1) is within a predetermined range. Nm / (Nw · gr ＭＤＵ )... (1) 3. The electric assist 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.

Images