Electrically assisted bicycle and method for controlling motor of electrically assisted bicycle

Abstract

To provide an electric assist bicycle in which motor stop against a human intention rarely occurs and the responsivity of motor stop along with a human intention is easily improved, and a method of controlling the motor.SOLUTION: An automobile is equipped with a torque sensor 59 that detects human driving force applied to a crank 52, a crank rotation speed detecting portion 65 that detects the rotation speed of the crank 52, and a motor 54 that generates assist driving force for assisting power rotating wheels 3 and 4. The bicycle 1 is equipped with a control device 70 that stops the motor 54 if determining that a state in which human driving force is a threshold value or less has been continuously kept and the rotation speed decreases by a predetermined rotation speed or more.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to an electrically assisted bicycle and a method for controlling a motor of an electrically assisted bicycle. [Background technology]

[0002] A conventional electrically assisted bicycle is described in Patent Document 1. This electrically assisted bicycle is designed to continuously maintain a state in which the human driving force is below a threshold, and to stop the motor when the crank has rotated a certain angle or more after the human driving force falls below the threshold. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-27753 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-mentioned electrically assisted bicycle, the motor is stopped when the crank has rotated a certain angle or more after the human driving force falls below a threshold value. Therefore, even if the person does not intend to stop the electrically assisted bicycle while it is traveling at high speed, there is a risk that the motor will stop if the person temporarily takes their feet off the pedals, and there is a risk that the motor will frequently stop against the person's will.

[0005] In order to avoid this problem, if the motor is stopped when the human driving force remains below a threshold for a certain period of time, it is difficult to improve responsiveness when stopping the motor. Therefore, if the electrically assisted bicycle is a mountain bike or the like that requires high responsiveness to operation, the motor will tend to continue to be driven against the user's will, making it difficult for the user to ride as they wish.

[0006] Therefore, an object of the present disclosure is to provide an electrically assisted bicycle that is less likely to cause the motor to stop against human will and that can easily improve the responsiveness of motor stopping in line with human will, and a method of controlling the motor of an electrically assisted bicycle. [Means for solving the problem]

[0007] In order to solve the above problems, the electrically assisted bicycle disclosed herein comprises a manual driving force detection unit that detects the manual driving force applied to the crank, a crank rotation speed detection unit that detects the rotation speed of the crank, a motor that generates an auxiliary driving force that supplements the power to rotate the wheels, and a control device that stops the motor when it is determined that the manual driving force is continuously maintained at or below a threshold value and that the rotation speed has decreased by a predetermined number or more.

[0008] Another aspect of an electrically assisted bicycle of the present disclosure includes a manual driving force detection unit that detects the manual driving force applied to the crank, a motor that generates an auxiliary driving force that supplements the power to rotate the wheels, a motor rotation speed detection unit that detects the motor rotation speed, and a control device that stops the motor when it is determined that the manual driving force is continuously maintained at or below a threshold value and that the rotation speed has decreased by a predetermined rotation speed or more.

[0009] In addition, the disclosed method for controlling a motor of an electrically assisted bicycle is a method for controlling a motor of an electrically assisted bicycle equipped with a motor that generates an auxiliary driving force that supplements the power to rotate the wheels, and stops the motor when the manual driving force applied to the crank is continuously maintained at or below a threshold value and the rotation speed of the crank decreases by more than a predetermined rotation speed.

[0010] Another aspect of the present disclosure is a method for controlling a motor of an electrically assisted bicycle equipped with a motor that generates an auxiliary driving force that supplements the power to rotate the wheels, and stops the motor when the manual driving force applied to the crank is continuously maintained at or below a threshold value and the motor rotation speed decreases by more than a predetermined rotation speed. Effect of the Invention

[0011] According to the electrically assisted bicycle of the present disclosure, motor stopping against the user's will is unlikely to occur, and it is easy to increase the responsiveness of motor stopping in line with the user's will. [Brief description of the drawings]

[0012] [Figure 1] 1 is a side view of an electrically assisted bicycle according to an embodiment of the present disclosure. [Diagram 2] FIG. 4 is a plan sectional view showing the structure of the motor unit in detail. [Diagram 3] 2 is a plan view of the rotating body of the motor unit as viewed from the width direction (left-right direction) of the bicycle. FIG. [Figure 4] 1 is a block diagram showing parts of an electrically assisted bicycle that are related to the control of the present disclosure. FIG. [Diagram 5] 4 is a flowchart showing an example of control performed by a control device when stopping a motor in an electrically assisted bicycle. [Figure 6] 1 is a graph showing the results of an investigation into the fluctuations in various physical quantities when an example of the control disclosed herein is performed and the electrically assisted bicycle is stopped, and shows the relationship between the manual driving force, the rotation speed of the crank, the current flowing through the motor, and the rotation speed of the motor, with the horizontal axis representing time. [Figure 7] 6 is a flowchart of control corresponding to FIG. 5 for a modified electrically assisted bicycle in which a reduced rotation speed of the motor is used as a measure for stopping the motor. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, the embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In addition, when multiple embodiments and modified examples are included below, it is assumed from the beginning that new embodiments will be constructed by appropriately combining the characteristic parts of those. In addition, in the following examples, the same components are given the same symbols in the drawings, and duplicated explanations are omitted. In addition, multiple drawings include schematic diagrams, and the dimensional ratios of length, width, height, etc. of each member do not necessarily match between different drawings. In addition, among the components described below, components that are not described in the independent claim that indicates the highest concept are optional components and are not essential components. In addition, when the word "approximately" is used in this specification, it is used in the same sense as the word "roughly speaking", and the requirement of "approximately ~" is satisfied if a person looks roughly ~. For example, the requirement of approximately circular is satisfied if a person looks roughly circular. In addition, in the following embodiments, a case will be described in which the electric-assisted bicycle 1 is a mountain bike, but the electric-assisted bicycle of the present disclosure may be any type of electric-assisted bicycle, for example, a cross bike, a city bike, etc. In the following description, the width direction (left-right direction) is the direction parallel to the extension direction of the rear wheel axle 33, and the front-rear direction is the direction perpendicular to both the height direction and width direction of the power-assisted bicycle 1.

[0014] FIG. 1 is a side view of an electric power-assisted bicycle 1 according to an embodiment of the present disclosure. As shown in FIG. 1, the electric power-assisted bicycle (hereinafter simply referred to as bicycle) 1 includes a frame 2, a front wheel 3, a rear wheel 4, a motor unit 5, a battery 6, a handlebar 7, a saddle 8, a crank arm 9, and pedals 10. The battery 6 includes, for example, one or more batteries, for example, secondary batteries such as lithium-ion batteries. The battery 6 supplies DC power to a motor 54 (FIG. 2) of the motor unit 5. The bicycle 1 assists the human driving force (pedaling force) of a person stepping on the pedals 10 with the auxiliary driving force of the motor 54 (FIG. 2) of the motor unit 5. The human driving force is a torque acting on a crank (crank shaft) 52 (FIG. 2). The motor unit 5 is a drive unit that assists the pedaling force of the pedals 10. The output of the motor 54 of the motor unit 5 is controlled by a control device 70 (FIG. 4). The control device 70 may be installed in any location. The control device 70 may be, for example, at least a portion of which is housed together with the motor 54 inside the unit case 11 of the motor unit 5 , and may be unitized with the motor 54 .

[0015] The crank arms 9 and the pedals 10 attached to one ends thereof are provided on each side of the bicycle 1, and the other ends of the pair of crank arms 9 are connected to each other by a crank 52 (Fig. 2). The crank 52 is rotated by human driving force, and the rotational force of the crank 52 is transmitted to a driving sprocket (front sprocket) 51 via a one-way clutch 56 (Fig. 2). The driving sprocket 51 is connected to a rear wheel sprocket 13 provided on the rear wheel 4 via a chain 12. As a result, the force applied to the pedal 10 is transmitted to the rear wheel 4 via the chain 12 and the rear wheel sprocket 13. The auxiliary power of the motor 54 is also transmitted to the rear wheel 4 via the chain 12.

[0016] The frame 2 is a framework capable of holding the front wheel 3, the rear wheel 4, and the motor unit 5. The frame 2 includes a lower pipe 20, a vertical pipe 21, two chain stays 22, two seat stays 23, an upper pipe 24, a head pipe 25, a front fork 26, and a bottom bracket 27. The lower pipe 20 connects the bottom bracket 27 to the head pipe 25. The lower pipe 20 extends obliquely upward and forward from the front end of the bottom bracket 27 to the head pipe 25. The lower pipe 20 has a battery housing section 29 that houses the battery 6. A removable cover 73 that covers the battery housing section 29 is attached to the lower pipe 20.

[0017] The bottom bracket 27 connects the lower end of the lower pipe 20 and the front end of the chain stay 22. In addition to the lower pipe 20 and the chain stay 22, the lower end of the stand pipe 21 is connected to the bottom bracket 27. The motor unit 5 is attached to the bottom bracket 27. The stand pipe 21 is a pipe that holds the saddle 8. The stand pipe 21 connects the bottom bracket 27 and the upper pipe 24. The stand pipe 21 extends obliquely upward and rearward from the upper end of the bottom bracket 27, and extends above the upper pipe 24. The saddle 8 is fixed to the stand pipe 21 in a state where its heightwise position can be adjusted.

[0018] The two chain stays 22 are pipes that connect the bottom bracket 27 and the seat stay 23. Each chain stay 22 extends from the rear end of the bottom bracket 27 to the rear end of the seat stay 23. The two chain stays 22 are spaced apart in the width direction (left-right direction), and the rear wheel 4 is disposed between the two chain stays 22. A bearing 15 that rotatably supports the rotation shaft of the rear wheel 4 is provided at the rear end of the chain stay 22. The seat stays 23 are pipes that connect the upper side of the vertical pipe 21 and the chain stays 22. Each seat stay 23 extends obliquely from the upper side of the vertical pipe 21 downward and rearward to the rear end of the chain stay 22. The two seat stays 23 are disposed with an interval in the width direction (left-right direction). One seat stay 23 is connected to one chain stay 22, and the other seat stay 23 is connected to the other chain stay 22.

[0019] The upper pipe 24 connects the head pipe 25 and the upper end of the stand pipe 21. The upper pipe 24 extends obliquely upward and forward from the upper side of the stand pipe 21 to the head pipe 25. The head pipe 25 connects the front end of the upper pipe 24 to the front end of the lower pipe 20. The head pipe 25 supports a front fork 26 and handlebars 7 rotatably about the central axis of the head pipe 25. The front wheel 3 is rotatably attached to the front fork 26.

[0020] The front fork 26 has a pair of legs 18 that support the front wheel axle 17, and a steering column 19 that extends upward from the upper ends of the legs 18 along the central axis of the head pipe 25. The front fork 26 is attached to the head pipe 25 by fitting the steering column 19 into the head pipe 25. The handlebars 7 are attached to the upper end of the steering column 19. As a result, when the handlebars 7 rotate about the central axis of the head pipe 25, the front fork 26 rotates about the central axis of the head pipe 25, and the front wheel 3 rotates about the central axis of the head pipe 25. The front wheel axle 17 tilts in the width direction as the front wheel 3 rotates about the central axis. The rear wheel 4 is supported by the two chain stays 22 so as to be rotatable about the axis of the rear wheel axle 33.

[0021] Fig. 2 is a plan sectional view showing the structure of the motor unit 5 in detail. Note that Fig. 2 illustrates a case where the motor unit 5 is a single-shaft motor unit in which the rotational force of the motor 54 is transmitted to the drive sprocket 51 via a reduction mechanism 57. However, the motor unit of the bicycle of the present disclosure may be a two-shaft motor unit in which the rotational force of the motor is transmitted to a sprocket for auxiliary power output, to which a chain is attached, via a reduction mechanism. The motor 54 may be, for example, a three-phase brushless DC motor.

[0022] 2, the motor unit 5 includes a cylindrical human power transmission body 53 to which the human power is transmitted by spline fitting, serration fitting or the like on the outer periphery of a crank 52 to which the human power is transmitted from the pedal 10 (see FIG. 1), and a force combiner 55 that combines the human power transmitted via the human power transmission body 53 and the auxiliary driving force from the motor 54. The human power transmission body 53 transmits the human power to the force combiner 55 via a one-way clutch 56.

[0023] At one end of the combiner 55, a large diameter gear portion 55a is formed to which the auxiliary driving force from the motor 54 is transmitted via a reduction mechanism 57. More specifically, an annular rotor 54b of the motor 54 is fixed to an output shaft 54a by press fitting, shrink fitting, cold fitting, or the like, and the output shaft 54a meshes with the small diameter gear portion 57a. The small diameter gear portion 57a ​​is fixed to the outer circumferential surface of an intermediate rotating shaft 57b, and the large diameter gear portion 55a meshes with the intermediate rotating shaft 57b. As a result, the rotational power generated by the motor 54 is reduced in speed and transmitted to the large diameter gear portion 55a.

[0024] A driving sprocket 51 is attached to the other end of the force combiner 55. The resultant force generated in the force combiner 55 is transmitted from the driving sprocket 51 to the rear wheel side via the chain 12. The motor unit 5 transmits the resultant force of the manual driving force and the auxiliary driving force to the chain 12 by meshing only the driving sprocket 51 with the chain 12.

[0025] The motor unit 5 includes a magnetostrictive torque sensor 59 as an example of a human-powered driving force detection unit that detects a human-powered driving force. The torque sensor 59 has a magnetostrictive generating unit provided on the outer circumferential surface of the human-power transmitting body 53 to which the human-powered driving force from the crank 52 is transmitted, and a coil 59a provided in a portion facing the outer circumferential surface to detect magnetic fluctuations in the magnetostrictive generating unit. When a person depresses the left and right pedals 10 (see FIG. 1), the crank 52 is twisted by the human-powered driving. The torque sensor 59 detects the twisted state of the human-power transmitting body 53 to which the human-powered driving force is transmitted from the crank 52. Note that, as the human-powered driving force detection sensor, a magnetostrictive torque sensor having a structure other than that disclosed in the present disclosure may be used, or a torque sensor other than the magnetostrictive torque sensor, such as a strain gauge torque sensor, may be used.

[0026] As described above, the one-way clutch 56 is attached to the end of the human power transmission body 53. This one-way clutch 56 is provided for the following reason. That is, in the control of the present disclosure, the motor unit 5 may be controlled to continue rotating the motor 54 for a while even after the person stops pedaling the pedal 10 by setting a threshold value (off torque) described later to 0. In such a case, if the one-way clutch 56 is not provided, the auxiliary driving force from the motor 54 will be transmitted to the crank 52, and the pedal 10 will tend to continue rotating on its own. Therefore, the one-way clutch 56 cuts off the auxiliary driving force from the motor 54 so that such a force does not act on the crank 52 or the pedal 10.

[0027] The motor unit 5 further includes a Hall IC (Integrated Circuit) 60 as an example of a motor rotation speed detector on the outer periphery of the rotor 54b. The Hall IC 60 has a built-in Hall element. When a current flows through the Hall element and a magnetic field (magnet) is brought close perpendicular to the direction of the current, the carrier that carries the current is affected by the Lorentz force. The Lorentz force generates a voltage (Hall voltage) perpendicular to the direction of the current and magnetic field (Hall effect). The Hall IC 60 detects the presence of a magnetic field (magnet) by detecting the Hall voltage. The Hall voltage increases in proportion to the magnetic flux density. According to Fleming's left-hand rule, the direction of the Hall voltage changes depending on the direction of the magnetic field (north pole or south pole). As a result, the Hall IC 60 can detect not only the presence of a magnetic field but also the direction of the magnetic field (north pole or south pole) based on the direction of the Hall voltage.

[0028] The Hall IC 60 includes an amplifier circuit including an operational amplifier and the like in addition to the Hall element, and the amplifier circuit amplifies the Hall voltage detected by the Hall element. When the rotor 54b rotates, the magnetic field around the Hall element fluctuates. Therefore, the Hall element detects the voltage fluctuation, and the rotation speed of the rotor 54b can be identified. The Hall IC 60 outputs an electric signal capable of identifying the rotation speed of the rotor 54b to the control device 70 (see FIG. 4). Note that the motor rotation speed detection unit has been described as being a Hall IC. However, the motor rotation speed detection unit may be any sensor capable of identifying the rotation speed of the rotor 54b, and may be, for example, a resolver or an electromagnetic rotation detector using a pulsar ring.

[0029] The motor unit 5 further includes a crank rotation speed detection unit 65. The crank rotation speed detection unit 65 includes a rotating member 61 and an optical sensor 68. The rotating member 61 includes a cylindrical intermediate cylinder 62 that is attached to the outer circumferential surface of the crank 52 and rotates integrally with the crank 52, and an annular rotating body 63 that is fixed to the outer circumferential surface of the intermediate cylinder 62. FIG. 3 is a plan view of the rotating body 63 as viewed from the width direction (left-right direction) of the bicycle 1. As shown in FIG. 3, the rotating body 63 has an attachment portion 63a that is fixed to the intermediate cylinder 62, and teeth (light-shielding portions) 63b that extend radially in a comb-like shape from the attachment portion 63a.

[0030] On the other hand, as shown in FIG. 2, the optical sensor 68 includes a light emitting unit 66 and a light receiving unit 67. The light emitting unit 66 and the light receiving unit 67 are installed on a stationary part of the bicycle 1 with a gap in the width direction between them and sandwiching the tooth portion 63b of the rotating body 63. The crank rotation speed detection unit 65 detects the tooth groove portion (light passing portion) between the tooth portion 63b by receiving the light emitted by the light emitting unit 66 with the light receiving unit 67, and conversely, detects the tooth portion 63b by not receiving the light emitted by the light emitting unit 66 with the light receiving unit 67. In this way, the crank rotation speed detection unit 65 detects the rotation speed of the intermediate cylinder 62, and detects the rotation speed of the crank 52, which is the same as the rotation speed of the intermediate cylinder 62, and the rotation speed (cadence) of the pedal 10, which is the same as the rotation speed of the intermediate cylinder 62.

[0031] In addition, two crank rotation number detection units 65 may be arranged at intervals in the circumferential direction of the rotating body 63 to specify the rotation direction of the crank 52. The crank rotation number detection unit may be any sensor that can specify the rotation number of the crank 52. For example, the rotating body 63 having teeth 63b that block light is provided, and light that passes through the tooth groove between the teeth 63b is detected. However, a similar rotating body may be provided, and a light receiving unit may be provided at a position that reflects light, so that the rotation position and the rotation number are detected by receiving the reflected light with the light receiving unit. Alternatively, the crank rotation number detection unit may be configured with a magnetic sensor installed to detect the rotation number of the crank 52, for example, an electromagnetic rotation detector using a resolver or a pulsar ring.

[0032] Fig. 4 is a block diagram showing parts of bicycle 1 related to the control of the present disclosure. As shown in Fig. 4, bicycle 1 further includes a motor drive switching element 76. The motor drive switching element 76 is included in an electric circuit that electrically connects battery 6 and motor 54. The motor drive switching element 76 is composed of, for example, a transistor. When the motor drive switching element 76 is turned on by a control signal from control device 70, DC power is supplied from battery 6 to motor 54. Conversely, when the motor drive switching element 76 is turned off by a control signal from control device 70, the supply of DC power from battery 6 to motor 54 is cut off.

[0033] The control device 70 receives signals from the torque sensor 59, the Hall IC 60, and the crank rotation speed detection unit 65, and controls the on / off of the motor drive switching element 76. The control device 70 is preferably configured by a computer, for example, a microcomputer, and includes a control unit 71 and a storage unit 72. The control unit 71, i.e., the processor, includes, for example, a CPU (Central Processing Unit). The storage unit 72 is configured by a hard disk drive (HDD), a semiconductor memory, etc., and the semiconductor memory is configured by a non-volatile memory such as a ROM (Read Only Memory) or a volatile memory such as a RAM (Random Access Memory). The storage unit 72 may be configured by only one storage medium, or may be configured by a plurality of different storage media. The CPU reads out and executes a program, etc., previously stored in the storage unit 72. The non-volatile memory previously stores a control program, a predetermined threshold value, etc. The volatile memory temporarily stores the read program and processing data. The control unit 71 includes a manual driving force calculation unit 71a, a crank rotation speed calculation unit 71b, a pedal position specification unit 71c, an off-torque determination unit 71d, a reduced rotation speed determination unit 71e, and a motor drive control unit 71f. The operation of each of these units in the control unit 71 will be described with reference to FIG. 5.

[0034] FIG. 5 is a flow chart showing an example of control performed by the control device 70 when stopping the motor 54 in the bicycle 1. Referring to FIG. 5, when the motor 54 is driven, the control starts, and in step S1, the manual driving force calculation unit 71a calculates the manual driving force based on the signal from the torque sensor 59 and information (e.g., a program) for calculating the manual driving force stored in the storage unit 72. In the following step S2, the off-torque determination unit 71d determines whether the manual driving force calculated in step S1 is equal to or less than a threshold value (off-torque). This threshold value information is stored in the storage unit 72 in advance. The threshold value may be any value equal to or greater than 0, and may be appropriately determined according to the specifications of the bicycle. The threshold value may also vary according to the riding conditions of the bicycle 1 and the user. For example, the threshold value may vary based on at least one of the speed and acceleration of the bicycle 1. The threshold value may also be appropriately changeable regardless of the specifications of the bicycle, and may also be appropriately changeable based on one or more of the sex, physique, and age of the user, for example.

[0035] If a negative determination is made in step S2, step S1 and subsequent steps are repeated. On the other hand, if a positive determination is made in step S2, the process proceeds to step S3, where the crank rotation speed calculation unit 71b calculates a first rotation speed of the crank 52 at the time when the manual driving force becomes equal to or less than the threshold value, based on the signal from the crank rotation speed detection unit 65 and information (e.g., a program) for calculating the crank rotation speed stored in the storage unit 72.

[0036] In the next step S4, the pedal position identification unit 71c identifies the pedal position at the time when the manual driving force becomes equal to or less than the threshold value. This identification is performed as follows. When the pedal 10 reaches the top dead center (the highest position of the pedal 10) or the bottom dead center (the lowest position of the pedal 10), it becomes difficult for the person to depress the pedal 10. Therefore, the force with which the person depresses the pedal 10 temporarily weakens when the pedal 10 reaches the top dead center or the bottom dead center, and as a result, the rotation speed of the pedal 10 (the rotation speed of the crank 52) also temporarily decreases. Conversely, when the pedal 10 reaches the middle between the top dead center and the bottom dead center, it becomes easier for the person to depress the pedal 10, and the rotation speed of the pedal 10 increases. In other words, the rotation speed of the pedal 10 periodically varies based on the position of the pedal 10. The pedal position identifying unit 71c identifies the position of the pedal 10 at the time when the manual driving force becomes equal to or less than a threshold value based on fluctuation information of the rotation speed of the pedal 10 (which corresponds to the rotation speed of the crank 52) from the crank rotation speed calculating unit 71b.

[0037] Next, in step S5, the reduced rotation speed determination unit 71e specifies the second rotation speed, which is the reduced rotation speed of the crank 52 that is a measure for stopping the motor 54. More specifically, for example, when the one pedal 10 is located within a predetermined angle range centered on the top dead center (the angle when the one pedal 10 rotates once is set to 360°), the reduced rotation speed determination unit 71e specifies the second rotation speed as 12 rpm, and otherwise, the reduced rotation speed determination unit 71e specifies the second rotation speed as 15 rpm. More generally, the second rotation speed set by the reduced rotation speed determination unit 71e when the one pedal 10 is located within a predetermined angle range centered on the top dead center is set smaller than the second rotation speed set by the reduced rotation speed determination unit 71e when the one pedal 10 is located in a region other than the above-mentioned angle range.

[0038] In the next step S6, the motor drive control unit 71f judges whether or not the state where the manual driving force is equal to or less than the threshold value is continuously maintained and the rotation speed of the crank 52 has decreased by equal to or more than the second rotation speed from the first rotation speed when the manual driving force is equal to or less than the threshold value based on the information on the manual driving force from the manual driving force calculation unit 71a, the information on the crank rotation speed from the crank rotation speed calculation unit 71b, the information on the first rotation speed, and the information on the second rotation speed. If the judgment in step S6 is negative, steps S1 and onward are repeated. On the other hand, if the judgment in step S6 is positive, the process proceeds to step S7, where the motor drive control unit 71f controls the motor drive switching element 76 to turn off to stop the motor 54, and the control ends.

[0039] Next, the reason why the stop control of the motor 54 of the present disclosure is superior will be described. FIG. 6 is a graph showing the results of an investigation into the fluctuations of various physical quantities when the bicycle 1 is stopped by performing an example of the control of the present disclosure, and is a graph showing the relationship between the manual driving force, the rotation speed of the crank 52 (the rotation speed of the pedal 10), the current flowing through the motor 54, and the rotation speed of the motor 54, with the horizontal axis representing time. In FIG. 6, the solid line represents the manual driving force, and the vertical axis represents the torque. Also, the dotted line represents the current flowing through the motor 54, and the vertical axis represents the amperes. Also, the dashed line represents the rotation speed of the crank 52, and the vertical axis represents the rotation speed. Also, the two-dot chain line represents the rotation speed of the motor 54, and the vertical axis represents the rotation speed. Also, in this stop control, 15 rpm is adopted as the second rotation speed regardless of the position of the pedal 10 when the manual driving force becomes equal to or less than the threshold, and the motor 54 is stopped when the rotation speed of the crank 52 decreases by 15 or more from when the manual driving force becomes equal to or less than the threshold.

[0040] In the graph of FIG. 6, the manual driving force becomes equal to or less than the threshold at time t1, and then, at time t2, the number of rotations of the crank 52 decreases by 15 or more from when the manual driving force becomes equal to or less than the threshold. In this control, the supply of power to the motor 54 is stopped at time t2. Therefore, the current flowing through the motor 54 drops sharply from time t2, and at time t3, no current flows through the motor 54 and the motor 54 stops. In the graph of FIG. 6, time t4 is the time 300 ms after time t1. In the control of the reference example, the supply of power to the motor 54 is stopped after a certain time, for example, 300 ms, has elapsed since the manual driving force became equal to or less than the threshold.

[0041] 6, time t3 at which current stops flowing to motor 54 under the control of the present disclosure is much earlier than time t4. Therefore, by adopting the control of the present disclosure, it is possible to improve the responsiveness of motor stopping in line with human will, compared to control that stops the supply of power to motor 54 a certain time after the manual driving force becomes equal to or less than a threshold value.

[0042] Furthermore, in this embodiment, the motor 54 is stopped when the rotation speed of the motor 54 drops by 15 or more from when the human driving force becomes equal to or less than the threshold value. Here, in a large number of tests (surveys) conducted by the inventor of the present application with a large number of people, when a person temporarily stops pedaling the pedals 10 due to fatigue or the like in a situation where the person does not want to stop the motor 54, the rotation speed of the crank 52 drops by only about 7 or 8 rpm at most, and the drop in the rotation speed remains at less than about 10 rpm. Therefore, by adopting 10 rpm or more, preferably 12 rpm or more, and more preferably 15 rpm or more as the second rotation speed, which is the reduced rotation speed serving as an index (measure) for stopping the motor 54, it is possible to suppress or prevent the motor 54 from stopping against the person's will, and to increase the responsiveness of the motor stopping in line with the person's will.

[0043] As described above, bicycle 1 of the present disclosure includes torque sensor (manual driving force detection unit) 59 that detects the manual driving force applied to crank 52, crank rotation speed detection unit 65 that detects the rotation speed of crank 52, and motor 54 that generates auxiliary driving force that supplements the power to rotate wheels 3, 4. Bicycle 1 also includes control device 70 that stops motor 54 when it is determined that the manual driving force is continuously maintained at or below a threshold value and that the rotation speed has decreased by a predetermined number of rotations or more.

[0044] According to the present disclosure, the state in which the manual driving force is equal to or less than the threshold value is continuously maintained, and the motor is stopped when the number of rotations of the crank 52 decreases by a predetermined number of rotations or more. Therefore, it is easier to increase the responsiveness of the motor stopping operation compared to control in which the motor is stopped after a predetermined time has elapsed since the manual driving force became equal to or less than the threshold value.

[0045] Furthermore, in comparison with a control that stops the motor when the crank rotates a certain angle or more after the manual driving force falls below a threshold, it is easier to prevent the motor from being stopped against the will of the person, and in particular, setting the second rotation speed to 12 rpm or more, for example 15 rpm, can almost certainly prevent the motor from being stopped against the will of the person. Note that, in order to increase the responsiveness of the motor stopping, it is preferable to set the second rotation speed to 30 rpm or less.

[0046] The control device 70 may also determine that the rotation speed of the crank 52 has decreased by the predetermined number of rotations or more when the rotation speed of the crank 52 has decreased by the second number of rotations or more from the first number of rotations when the manual driving force becomes the threshold value. The control device 70 may also stop the motor 54 when the state in which the manual driving force is equal to or less than the threshold value is continuously maintained and the rotation speed of the crank 52 has decreased by the second number of rotations or more from the first number of rotations when the manual driving force becomes equal to or less than the threshold value.

[0047] According to this configuration, the control for stopping the motor 54 can be simplified, and the control for stopping the motor 54 can be easily and accurately executed.

[0048] The second rotation speed may vary depending on the position of the pedal 10 when the manual driving force becomes equal to or less than the threshold value.

[0049] According to the present configuration, motor stop control can be executed that reflects the ease or difficulty of a person pedaling, so that not only is responsiveness high, but motor stop control can also be easily executed that accurately reflects the person's intention to stop the motor.

[0050] The present disclosure is not limited to the above-described embodiment and its modified examples, and various improvements and modifications are possible within the scope of the claims of the present application and their equivalents.

[0051] For example, in the above embodiment, the time that the manual driving force remains below a threshold value is not related to the control to stop the motor 54. However, the bicycle control device of the present disclosure may stop the motor when the state in which the manual driving force remains below the threshold value for a predetermined period of time.

[0052] According to this configuration, the specified number of revolutions and the specified time can be appropriately changed based on the user's gender, build, and age, making it easier to realize a bicycle that is more versatile and meets the needs of the user.

[0053] Also, in the above description, the control device 70 determines that the rotation speed of the crank 52 has decreased by a predetermined number of rotations or more when the rotation speed of the crank 52 has decreased by a second number of rotations or more from a first rotation speed at which the manual driving force became the threshold value in a state in which the manual driving force applied to the crank is continuously maintained at or below the threshold value, and stops the motor 54. However, the time when the rotation speed of the crank 52 starts to decrease may be a time before the time when the manual driving force became the threshold value. Then, the control device may stop the motor when the rotation speed of the crank has decreased by a predetermined number of rotations or more and the state in which the manual driving force applied to the crank is continuously maintained at or below the threshold value is continuously maintained.

[0054] In addition, the reduced rotation speed of the crank 52 is used as a measure for stopping the motor 54. However, the rotation speed of the motor 54 shown by the two-dot chain line in Fig. 6 fluctuates in a similar manner to the rotation speed of the crank 52 shown by the one-dot chain line in Fig. 6. More specifically, the rotation speed of the motor 54 and the rotation speed of the crank 52 are similar in that they first gradually decrease after the manual driving force becomes equal to or less than a threshold value, and then decrease significantly. Therefore, the reduced rotation speed of the motor 54 may be used as a measure for stopping the motor 54, instead of the reduced rotation speed of the crank 52.

[0055] That is, the bicycle of the present disclosure may include a torque sensor (manual driving force detection unit) 59 that detects the manual driving force applied to the crank 52, a motor 54 that generates an auxiliary driving force that supplements the power to rotate the wheels 3, 4, and a Hall IC (motor rotation speed detection unit) 60 that detects the rotation speed of the motor 54. The bicycle of the present disclosure may also include a control device that stops the motor 54 when it is determined that the manual driving force is continuously maintained at or below a threshold value and the rotation speed of the motor 54 has decreased by a predetermined rotation speed or more. In this case, the control device may determine that the rotation speed of the motor 54 has decreased by the predetermined rotation speed or more when the rotation speed of the motor 54 has decreased by a second rotation speed or more from a first rotation speed when the manual driving force becomes the threshold value. The control device may also stop the motor 54 when it is determined that the rotation speed of the motor 54 has decreased by a second rotation speed or more from a first rotation speed when the manual driving force becomes the threshold value or less.

[0056] With this bicycle, just as in the case where the reduced rotation speed of the crank 52 is used as a measure for stopping the motor 54, it is less likely that the motor will stop against the person's will, and it is easier to increase the responsiveness of the motor stopping in a way that is in line with the person's will.

[0057] FIG. 7 is a flow chart of control corresponding to FIG. 5 for a bicycle of a modified example in which the reduced rotation speed of the motor 54 is used as a measure for stopping the motor 54. The control unit of the bicycle of this modified example, in comparison with the control unit 71 shown in FIG. 4, has a motor rotation speed calculation unit instead of the crank rotation speed calculation unit 71b, and has a motor reduced rotation speed determination unit that determines the reduced rotation speed of the motor 54 instead of the reduced rotation speed determination unit 71e that determines the reduced rotation speed of the crank 52. Furthermore, in comparison with the control unit 71 shown in FIG. 4, the control unit of the bicycle of this modified example uses the rotation speed of the motor 54 instead of the rotation speed of the crank 52 as a measure for the motor drive control unit to determine motor stop. Furthermore, in comparison with the storage unit 72 shown in FIG. 4, the memory unit of the bicycle of this modified example does not store information about the rotation of the pedal 10, but instead stores information about the rotation of the pedal 10.

[0058] 7, in this bicycle, when the motor 54 is driven, control is started, the above-mentioned step S1 is performed, and the manual driving force calculation unit 71a calculates the manual driving force. Then, the above-mentioned step S2 is performed, and the off-torque determination unit 71d determines whether the manual driving force calculated in step S1 is equal to or less than the threshold value (off-torque). If a negative determination is made in step S2, step S1 and subsequent steps are repeated.

[0059] On the other hand, if the determination in step S2 is affirmative, step S13 is performed instead of step S3, and the motor rotation speed calculation unit calculates the first rotation speed of the motor 54 at the time when the manual driving force becomes equal to or less than the threshold value based on the signal from the Hall IC 60 and the information (e.g., a program) for calculating the motor rotation speed stored in the storage unit. After that, the above-mentioned step S4 is performed, and the pedal position identification unit 71c identifies the pedal position at the time when the manual driving force becomes equal to or less than the threshold value.

[0060] In the next step S15, the motor reduced rotation speed determination unit specifies a second rotation speed, which is a reduced rotation speed of the motor 54 that is a measure for stopping the motor 54. Here, the second rotation speed set by the motor reduced rotation speed determination unit when the one pedal 10 is located within a predetermined angle range centered on the top dead center is set to be smaller than the second rotation speed set by the motor reduced rotation speed determination unit when the one pedal 10 is located in a region outside the above-mentioned angle range.

[0061] In the next step S16, the motor drive control unit judges whether or not the state in which the manual driving force is equal to or less than the threshold value is continuously maintained and the rotation speed of the motor 54 has decreased by equal to or more than the second rotation speed from the first rotation speed when the manual driving force is equal to or less than the threshold value based on the information on the manual driving force from the manual driving force calculation unit 71a, the information on the motor rotation speed from the motor rotation speed calculation unit, the information on the first rotation speed, and the information on the second rotation speed. If the judgment in step S16 is negative, steps S1 and onward are repeated. On the other hand, if the judgment in step S16 is positive, the process proceeds to step S7, where the motor drive control unit controls the motor drive switching element 76 to turn off to stop the motor 54, and the control ends.

[0062] In this modified bicycle as well, the second rotation speed varies depending on the position of the pedal 10 when the human-powered driving force falls below the threshold. Therefore, motor stop control can be executed that reflects the ease or difficulty of pedaling the pedal 10, and motor stop control can be executed that is not only highly responsive but also accurately reflects the person's intention to stop the motor. Note that, regardless of whether the reduced rotation speed of the crank 52 or the reduced rotation speed of the motor 54 is used as the measure for stopping the motor 54, the second rotation speed (value of the reduced rotation speed) used to determine whether to stop the motor 54 may be a constant value regardless of the position of the pedal 10 when the human-powered driving force falls below the threshold. [Explanation of symbols]

[0063] 1 bicycle, 5 motor unit, 6 battery, 9 crank arm, 10 pedal, 11 unit case, 29 battery accommodating section, 52 crank, 53 human power transmission body, 54 motor, 55 combined force body, 57 reduction mechanism, 59 torque sensor, 60 Hall IC, 65 crank rotation speed detection section, 70 control device, 71 control section, 71a human power driving force calculation section, 71b crank rotation speed calculation section, 71c pedal position identification section, 71d off-torque determination section, 71e reduced rotation speed determination section, 71f motor drive control section, 72 memory section, 76 motor drive switching element.

Claims

1. a manual driving force detection unit that detects a manual driving force applied to the crank; a crank rotation speed detection unit that detects the rotation speed of the crank; A motor that generates an auxiliary driving force that supplements the power that rotates the wheels; a control device that stops the motor when the state in which the manual driving force is equal to or less than a threshold value is continuously maintained and the rotation speed is reduced by equal to or more than a second rotation speed from a first rotation speed at which the manual driving force becomes the threshold value, The second rotation speed varies depending on the pedal position when the human driving force becomes equal to or less than the threshold value.

2. a manual driving force detection unit that detects a manual driving force applied to the crank; A motor that generates an auxiliary driving force that supplements the power that rotates the wheels; a motor rotation speed detection unit that detects the rotation speed of the motor; a control device that stops the motor when it is determined that the manual driving force is continuously maintained at or below a threshold value and the rotation speed is reduced by a predetermined rotation speed or more; An electrically assisted bicycle.

3. 3. The electrically assisted bicycle according to claim 2, wherein the control device determines that the rotation speed has decreased by more than the predetermined rotation speed when the rotation speed has decreased by more than a second rotation speed from a first rotation speed at which the manual driving force became the threshold value, and the second rotation speed varies depending on the position of the pedal when the manual driving force became equal to or less than the threshold value.

4. 4. The electrically assisted bicycle according to claim 1, wherein the control device stops the motor even if the state in which the manual driving force is equal to or less than a threshold value is maintained for a predetermined period of time.

5. a manual driving force detection unit that detects a manual driving force applied to the crank; a crank rotation speed detection unit that detects the number of rotations of the crank; and a motor that generates an auxiliary driving force that supplements the power that rotates the wheels. a control device that stops the motor when it is determined that the manual driving force is continuously maintained at or below a threshold value and the rotation speed is reduced by a predetermined rotation speed or more; The control device determines that the rotation speed has decreased by more than the predetermined rotation speed when the rotation speed has decreased by 10 rpm or more from the rotation speed at which the human driving force reached the threshold value.

6. 1. A method for controlling a motor of an electrically assisted bicycle that is provided with a motor that generates an auxiliary driving force that supplements the power that rotates a wheel, comprising: When the state in which the manual driving force applied to the crank is equal to or less than a threshold value is continuously maintained and the number of rotations of the crank is reduced by a predetermined number of rotations or more, the motor is stopped; A method for controlling a motor of an electrically assisted bicycle, determining that the rotation speed has decreased by more than the predetermined rotation speed when the rotation speed has decreased by 10 rpm or more from the rotation speed at which the human driving force reached the threshold value.

7. 1. A method for controlling a motor of an electrically assisted bicycle that is provided with a motor that generates an auxiliary driving force that supplements the power that rotates a wheel, comprising: A method for controlling a motor of an electrically assisted bicycle, which stops the motor when the manual driving force applied to the crank is continuously maintained at or below a threshold value and the rotation speed of the motor decreases by more than a predetermined rotation speed.

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