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

Abstract

To provide an electric assist bicycle and the like capable of shortening time until assist works when a human restarts pedaling at inertia traveling.SOLUTION: A bicycle 1 is equipped with a motor 54 that is assist-driven to generate assist driving force for assisting power rotating wheels 3 and 4, a vehicle speed sensor 69 that detects a vehicle speed, a torque sensor 59 that detects human driving force applied to a crank shaft 52, a human drive rotation speed detecting portion 65 that detects the rotation speed of the crank shaft 52 rotated by human driving force, and a control device 70 that assist-drives and preceding-drives the motor 54. The control device 70 preceding-drives the motor 54 when a first condition that the vehicle speed is within a predetermined range larger than 0, a second condition that human driving force is less than a first threshold value larger than 0, and a third condition that the rotation speed of the crank shaft 52 is a second threshold value or more that is larger than 0, are satisfied.SELECTED DRAWING: Figure 4

Description

[Technical Field]

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

[0002] A conventional electrically assisted bicycle is described in Patent Document 1. In this electrically assisted bicycle, when the human driving force exerted by the pedals reaches a certain level, the motor is activated and generates an auxiliary driving force that assists the power that rotates the wheels. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-214157 Summary of the Invention [Problem to be solved by the invention]

[0004] The inventors of this application discovered the following new problem: In more detail, when a person pedals while an electrically assisted bicycle is coasting, the auxiliary driving force generated by the motor cannot assist the power to rotate the wheel unless the rotation speed of the motor-driven combiner unit, which combines the auxiliary driving force and the human-powered driving force, is equal to or exceeds the rotation speed of the human-powered combiner unit, such as the crankshaft.

[0005] In this context, when a person starts pedaling an electrically assisted bicycle from a stationary state, the rotation speed of the crankshaft is unlikely to increase suddenly. Therefore, the rotation speed of the motor-driven combiner quickly becomes equal to or exceeds the rotation speed of the crankshaft or other parts of the human-powered combiner, making it easy to quickly apply assistance from the motor's auxiliary driving force.

[0006] However, when an electrically assisted bicycle is coasting, that is, when a person temporarily stops pedaling while riding the electrically assisted bicycle, the rotation speed of the crankshaft rises sharply in a short period of time when the person resumes pedaling. As a result, it takes time for the rotation speed of the motor-driven combiner part to exceed the rotation speed of the crankshaft or other part of the human-powered combiner part, and the assist provided by the motor's auxiliary driving force tends to take a long time to take effect.

[0007] Therefore, an object of the present disclosure is to provide an electrically assisted bicycle and a method for controlling the motor of an electrically assisted bicycle that can shorten the time it takes for assistance to take effect when a person resumes pedaling during coasting. [Means for solving the problem]

[0008] In order to solve the above problems, the electrically assisted bicycle according to the present disclosure includes a motor that generates an auxiliary driving force to supplement the power that rotates the wheels by auxiliary driving, a vehicle speed detection unit that detects the vehicle speed, a manual driving force detection unit that detects the manual driving force applied to the crankshaft, a manual driving rotation speed detection unit that detects the rotation speed of a rotor that is rotated by the manual driving force, and a motor. Drive The control device includes a first condition that the vehicle speed is within a predetermined range greater than 0, a second condition that the manual driving force is less than a first threshold greater than 0, and a third condition that the rotation speed of the rotating body is equal to or greater than a second threshold greater than 0. Mukaku When the operating conditions are met, the motor Drive Move.

[0009] In addition, the auxiliary drive of the motor can assist the power to rotate the wheels, while the motor Drive The power may not be able to assist in turning the wheels.

[0010] Furthermore, a control method for a motor of an electrically assisted bicycle according to the present disclosure is a control method for a motor of an electrically assisted bicycle equipped with a motor that generates an auxiliary driving force that assists the power to rotate the wheel, and includes a first condition that the vehicle speed is within a predetermined range greater than 0, a second condition that the manual driving force applied to the crankshaft is less than a first threshold greater than 0, and a third condition that the rotation speed of a rotating body rotated by the manual driving force is equal to or greater than a second threshold greater than 0. Mukaku When the operating conditions are met, the motor Drive Move. [Effects of the Invention]

[0011] According to the electrically assisted bicycle of the present disclosure, it is possible to shorten the time it takes for the assist to take effect when the rider resumes pedaling during coasting. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a side view of an electrically assisted bicycle according to a first embodiment of the present disclosure. [Figure 2] FIG. 2 is a plan cross-sectional view showing in detail the structure of the motor unit of the electrically assisted bicycle. [Figure 3] FIG. 2 is a plan view of the light blocking body when viewed from the width direction (left-right direction) of the electrically assisted bicycle. [Figure 4] FIG. 2 is a block diagram showing parts of an electrically assisted bicycle that are related to the control of the present disclosure. [Figure 5] 4 is a flowchart showing an example of control performed by the control device when the power-assisted bicycle is coasting. [Figure 6] 1 is a graph showing the results of an investigation into fluctuations in various physical quantities when a motor is driven using an example of the control of the present disclosure, and showing the relationship between vehicle speed, manual driving force, crankshaft rotation speed, current flowing through the motor, and motor rotation speed, with the horizontal axis representing time. [Figure 7] 10 is a graph showing an example of fluctuations in various physical quantities in a test conducted with the rear wheel of an electrically assisted bicycle raised off the ground using a stand when an example of control according to the present disclosure is employed. [Figure 8] 6 is a flowchart corresponding to FIG. 5 in the control of a modified example. [Figure 9] FIG. 10 is a plan sectional view corresponding to FIG. 2 of an electrically assisted bicycle according to a second embodiment. [Figure 10] 10 is a flowchart showing an example of control performed by a control device of a second embodiment when an electrically assisted bicycle is coasting. DETAILED DESCRIPTION OF THE INVENTION

[0013] Embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. It is anticipated that, when multiple embodiments or variations are included below, new embodiments can be constructed by appropriately combining their characteristic features. In the following examples, identical components are designated by the same reference numerals in the drawings, and redundant explanations will be omitted. The drawings include schematic diagrams, and the dimensional ratios of the length, width, height, and other dimensions of each component do not necessarily match between different drawings. Among the components described below, components not recited in the independent claims that represent the highest concept are optional and not essential. In this specification, the term "approximately" is used in the same sense as "roughly speaking," and the requirement "approximately" is met if a person looks roughly like... For example, the requirement "approximately circular" is met if a person looks roughly circular. In the following embodiments, the electrically assisted bicycle 1 is described as a mountain bike; however, the electrically assisted bicycle of the present disclosure may be any type of electrically assisted bicycle, such as a cross bike or a city bike. Furthermore, 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 the width direction of the power-assisted bicycle 1. Furthermore, the present disclosure is not limited to the embodiments and their modifications described below, and various improvements and modifications are possible within the matters set forth in the claims of this application and their equivalents.

[0014] (First embodiment) FIG. 1 is a side view of an electrically assisted bicycle 1 according to a first embodiment of the present disclosure. As shown in FIG. 1, the electrically 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, crank arms 9, and pedals 10. The battery 6 includes, for example, one or more batteries, such as 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) exerted by a person pedaling the pedals 10 with the auxiliary driving force provided by the motor 54 (FIG. 2) of the motor unit 5. The human driving force is torque acting on a crankshaft 52 (FIG. 2), which is an example of a rotating body. The motor unit 5 is a drive unit that assists the human driving force applied to the crankshaft 52 when the person pedals 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 anywhere. The control device 70 may be unitized with the motor 54 by, for example, having at least a portion housed together with the motor 54 in the unit case 11 of the motor unit 5.

[0015] The crank arms 9 and pedals 10 attached to one end 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 crankshaft 52 (Fig. 2). The crankshaft 52 is a rotating body that is rotated by manual driving force, and the rotational force of the crankshaft 52 is transmitted to a drive sprocket (front sprocket) 51 via a force combiner 55 (Fig. 2). The drive sprocket 51 is connected via a chain 12 to a rear wheel sprocket 13 provided on the rear wheel 4. As a result, the manual driving force applied to the crankshaft 52 is transmitted to the rear wheel 4 via the chain 12 and the rear wheel sprocket 13. In addition, auxiliary power from a motor 54 is also transmitted to the rear wheel 4 via the chain 12.

[0016] The frame 2 is a framework capable of holding a front wheel 3, a rear wheel 4, and a 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 29 that houses a battery 6. A removable cover 73 that covers the battery housing 29 is attached to the lower pipe 20.

[0017] The bottom bracket 27 connects the lower end of the lower pipe 20 to 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 also 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 to the upper pipe 24. The stand pipe 21 extends obliquely upward and rearward from the upper end of the bottom bracket 27, and extends higher than the upper pipe 24. The saddle 8 is fixed to the stand pipe 21 in a state where its height position can be adjusted.

[0018] The two chainstays 22 are pipes that connect the bottom bracket 27 and the seat stays 23. Each chainstay 22 extends from the rear end of the bottom bracket 27 to the rear end of the seat stay 23. The two chainstays 22 are spaced apart in the width direction (left-right direction), and the rear wheel 4 is disposed between the two chainstays 22. A bearing 15 that rotatably supports the rotation shaft of the rear wheel 4 is installed at the rear end of each chainstay 22.

[0019] The seat stays 23 are pipes that connect the upper side of the stand pipe 21 to the chain stays 22. Each seat stay 23 extends obliquely from the upper side of the stand pipe 21 downward and rearward to the rear end of the chain stay 22. The two seat stays 23 are arranged with a gap between them in the width direction (left and 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.

[0020] 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.

[0021] 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 with respect to the width direction as the front wheel 3 rotates about the central axis. The rear wheel 4 is supported by the two chainstays 22 so as to be rotatable about the axis of the rear wheel axle 33.

[0022] FIG. 2 is a plan cross-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 also be a two-shaft motor unit in which the rotational force of the motor is transmitted via a reduction mechanism to a sprocket for auxiliary power output, to which a chain is attached. Furthermore, the motor 54 can be configured, for example, as a three-phase brushless DC motor.

[0023] 2, the motor unit 5 includes a cylindrical manual power transmission body 53 to which manual driving force from the pedals 10 (see FIG. 1) is transmitted by spline fitting, serration fitting, or the like, on the outer periphery of a crankshaft 52 to which manual driving force is transmitted, and a force combiner 55 that combines the manual driving force transmitted via the manual power transmission body 53 and the auxiliary driving force from the motor 54. The manual driving force from the manual power transmission body 53 is transmitted to the force combiner 55 via an intermediate cylindrical body 62.

[0024] A large-diameter gear portion 55a is formed at one end of the force combiner 55, to which 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 a small-diameter gear portion 57a. The small-diameter gear portion 57a ​​is fixed to the outer peripheral surface of an intermediate rotating shaft 57b via a one-way clutch 64, 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 transmitted to the force combiner 55 after being reduced in speed by the reduction mechanism 57.

[0025] The one-way clutch 64 interrupts the power transmission path through which the manual driving force is transmitted to the motor 54. More specifically, the one-way clutch 64 is provided to substantially prevent the rotor 54b of the motor 54 from rotating when the pedals 10 are operated in a case where the remaining capacity of the battery 6 (see FIG. 1) that drives the motor 54 is exhausted. In other words, if the one-way clutch 64 were not provided, when the pedals 10 were operated in a case where the remaining capacity of the battery was exhausted, the rotor 54b of the motor 54 would also rotate due to the manual driving force applied to the crankshaft 52. This would cause drag resistance due to the cogging torque of the motor 54, and a large force would be required to rotate the pedals 10.

[0026] In contrast, with the one-way clutch 64, power transmission between the combiner body 55 and the motor 54 is substantially interrupted unless the rotational speed of the motor 54 after being reduced by the reduction mechanism 57 exceeds the rotational speed of the crankshaft 52. Therefore, when the remaining battery charge is depleted and the pedals 10 are operated, the rotor 54b of the motor 54 is less likely to rotate, thereby preventing the user from exerting excessive force due to cogging torque of the motor 54. Conversely, with the one-way clutch 64, unless the rotational speed of the motor 54 after being reduced by the reduction mechanism 57 exceeds the rotational speed of the crankshaft 52, the auxiliary driving force generated by the motor 54 cannot assist the power that rotates the wheels 3 and 4. The one-way clutch for reducing the drag resistance may be disposed elsewhere in the reduction mechanism, or may be disposed between the output shaft 54a and the rotor 54b of the motor 54.

[0027] A drive 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 drive sprocket 51 to the rear wheel 4 side via the chain 12. The motor unit 5 transmits the resultant force, which is a combination of the manual driving force and the auxiliary driving force, to the chain 12 by meshing only the drive sprocket 51 with the chain 12.

[0028] The motor unit 5 includes a magnetostrictive torque sensor 59 as an example of a human-powered driving force detection unit that detects human-powered driving force. The torque sensor 59 includes 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 crankshaft 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 crankshaft 52 is twisted by the human-powered driving. The torque sensor 59 detects the torsional state of the human-power transmitting body 53 to which the human-powered driving force is transmitted from the crankshaft 52. Note that a magnetostrictive torque sensor having a structure other than that disclosed herein may be used as the human-powered driving force detection sensor, or a torque sensor other than the magnetostrictive torque sensor, such as a strain gauge torque sensor, may be used.

[0029] The motor unit 5 further includes a Hall IC (Integrated Circuit) 60, an example of a motor rotation speed detector, mounted on the outer periphery of the rotor 54b. The Hall IC 60 incorporates a Hall element. When a current flows through the Hall element and a magnetic field (magnet) is brought close perpendicular to the current, the carrier of the current is affected by the Lorentz force. The Lorentz force generates a voltage (Hall voltage) perpendicular to 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 or south pole). This allows the Hall IC 60 to detect not only the presence of a magnetic field but also its direction (north or south pole) based on the direction of the Hall voltage.

[0030] In addition to the Hall element, the Hall IC 60 also incorporates an amplifier circuit, such as an operational amplifier, which amplifies the Hall voltage detected by the Hall element. When the rotor 54b rotates, the magnetic field around the Hall element fluctuates. The Hall element detects the voltage fluctuation, thereby determining the rotation speed of the rotor 54b. The Hall IC 60 outputs an electrical signal that can determine the rotation speed of the rotor 54b to the control device 70 (see FIG. 4). Note that the motor rotation speed detector has been described as the Hall IC 60. However, the motor rotation speed detector may be any sensor that can determine the rotation speed of the rotor 54b, and may be, for example, a resolver or an electromagnetic rotation detector using a pulser ring.

[0031] The motor unit 5 further includes a manual drive rotation speed detection unit 65. The manual drive rotation speed detection unit 65 has 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 crankshaft 52 and rotates integrally with the crankshaft 52, and an annular light blocking body 63 that is fixed to the outer circumferential surface of the intermediate cylinder 62. Figure 3 is a plan view of the light blocking body 63 as viewed from the width direction (left-right direction) of the bicycle 1. As shown in Figure 3, the light blocking body 63 has an attachment portion 63a that is fixed to the intermediate cylinder 62, and teeth (light blocking portions) 63b that extend radially in a comb-like shape from the attachment portion 63a.

[0032] 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 portion of the bicycle 1 with a widthwise gap between them and the tooth portion 63b of the light-shielding body 63 sandwiched between them. The manual-drive rotation speed detection unit 65 detects the tooth grooves (light-transmitting portions) between the tooth portions 63b by receiving the light emitted by the light-emitting unit 66 with the light-receiving unit 67, and conversely, detects the tooth portions 63b when the light-receiving unit 67 fails to receive the light emitted by the light-emitting unit 66. In this way, the manual-drive rotation speed detection unit 65 detects the rotation speed of the intermediate cylinder 62, and detects the rotation speed of the crankshaft 52, which is the same as the rotation speed of the intermediate cylinder 62, and the rotation speed (cadence) of the pedals 10, which is the same as the rotation speed of the intermediate cylinder 62.

[0033] Alternatively, two manual-driven rotation speed detectors 65 may be arranged at intervals around the periphery of the light shielding body 63 to identify the rotation direction of the crankshaft 52. The manual-driven rotation speed detector may be any sensor capable of identifying the rotation speed of the crankshaft 52. For example, the description has been given of a case in which a light shielding body 63 having light-blocking teeth 63b is provided and light passing through the tooth gaps between the teeth 63b is detected. However, a similar light shielding body may be provided and a light receiving unit may be provided at a position that reflects light, and the rotation position and rotation speed may be detected by receiving the reflected light with the light receiving unit. Alternatively, the manual-driven rotation speed detector may be a magnetic sensor installed to detect the rotation speed of the crankshaft 52, such as an electromagnetic rotation detector using a resolver or a pulser ring.

[0034] Figure 4 is a block diagram showing parts of bicycle 1 that are relevant to the control of the present disclosure. As shown in Figure 4, bicycle 1 further includes a vehicle speed sensor 69 and a motor drive switching element 76. Vehicle speed sensor 69 is attached to the rotation support portion of rear wheel 4 (see Figure 1) and detects the traveling speed of bicycle 1 from the number of rotations per unit time of rear wheel 4. Information on the number of rotations of rear wheel 4 detected by vehicle speed sensor 69 is transmitted to control device 70. Vehicle speed sensor 74 is composed of, for example, a wheel sensor or the like.

[0035] The motor drive switching element 76 is included in an electric circuit that electrically connects the battery 6 and the motor 54. The motor drive switching element 76 is configured by, for example, a transistor. When the motor drive switching element 76 is turned on by a control signal from the control device 70, DC power is supplied from the battery 6 to the motor 54. Conversely, when the motor drive switching element 76 is turned off by a control signal from the control device 70, the supply of DC power from the battery 6 to the motor 54 is cut off. The control device 70 adjusts the power supplied to the motor 54 by changing the duty ratio in pulse width modulation control (PWM (Pulse Width Modulation) control) of the motor 54, and adjusts the auxiliary driving force that the motor 54 applies to the force combiner 55.

[0036] The control device 70 receives signals from the vehicle speed sensor 69, the torque sensor 59, the Hall IC 60, and the manual drive 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 by multiple different storage media. The CPU reads and executes programs and the like stored in the storage unit 72. The non-volatile memory stores control programs, predetermined thresholds, etc. in advance. The volatile memory temporarily stores the read programs and processing data. The control unit 71 has a vehicle speed calculation unit 71a, a manual driving force calculation unit 71b, a manual driving rotation speed calculation unit 71c, a motor rotation speed calculation unit 71d, a power determination unit 71e, first to third condition determination units 71f, a fourth condition determination unit 71g, and a motor control unit 71h.

[0037] The vehicle speed calculation unit 71a calculates the vehicle speed based on a signal from the vehicle speed sensor 69 and information (e.g., a program) for calculating the vehicle speed stored in the storage unit 72. The manual driving force calculation unit 71b calculates the manual driving force based on a signal from the torque sensor 59 and information (e.g., a program) for calculating the manual driving force stored in the storage unit 72. The manual driving rotation speed calculation unit 71c calculates the rotation speed of the crankshaft 52 based on a signal from the manual driving rotation speed detection unit 65 and information (e.g., a program) for calculating the crankshaft rotation speed stored in the storage unit 72. The motor rotation speed calculation unit 71d calculates the rotation speed of the motor 54 based on a signal from the Hall IC 60 and information (e.g., a program) for calculating the motor rotation speed stored in the storage unit.

[0038] The power specifying unit 71e specifies the power to be supplied to the motor 54 based on information on the rotation speed of the crankshaft 52 from the manual drive rotation speed calculation unit 71c and map information that defines the correspondence between the rotation speed of the crankshaft 52 and the power to be supplied to the motor 54. The map information is pre-stored in the storage unit 72. In the map information, for example, the rotation speed range of the crankshaft 52 is divided into N (N is any natural number equal to or greater than 2) ranges. The map information also associates different powers with different ranges. The map information also associates the same power with the rotation speed of the crankshaft 52 within the same range. The power increases as the rotation speed of the crankshaft 52 increases in the range.

[0039] The first to third condition determination units 71f determine whether or not all of the first, second, and third conditions are met based on vehicle speed information from the vehicle speed calculation unit 71a, manual driving force information from the manual driving force calculation unit 71b, and rotation speed information of the crankshaft 52 from the manual driving rotation speed calculation unit 71c. The first condition is that the vehicle speed is within a predetermined range greater than 0, and the predetermined range can be selected, for example, from 4 km / h to 23 km / h. In this example, 23 km / h is selected as the upper limit because Japanese regulations only allow assistance by the motor 54 up to 24 km / h.

[0040] The second condition is that the manual driving force is less than a first threshold value that is greater than 0, and the first threshold value can be selected, for example, as 10 Nm. The first threshold value can be less than the on-torque. The third condition is that the rotation speed of the crankshaft 52 is equal to or greater than a second threshold value that is greater than 0, and the second threshold value can be selected, for example, as 1 rpm. Note that the predetermined range, the first threshold value, and the second threshold value are not limited to the ranges and values ​​described above.

[0041] The fourth condition determination unit 71g determines whether the fourth condition is met based on information about the rotation speed of the motor 54 from the motor rotation speed calculation unit 71d and information about the rotation speed of the crankshaft 52 from the manual drive rotation speed calculation unit 71c. The fourth condition is that the value obtained by dividing the rotation speed of the motor 54 by the rotation speed of the crankshaft 52 is equal to or less than a third threshold value. As the third threshold value, for example, a reduction ratio of the rotation speed of the motor 54 can be selected. The reduction ratio of the rotation speed of the motor 54 is defined as the rotation speed of the rotor 54b / the rotation speed of the large diameter gear portion 55a. For example, 30 can be selected as the third threshold value. Note that the third threshold value is not limited to 30. Furthermore, the motor control unit 71h controls the rotation speed of the rotor 54b by controlling the power supplied to the motor 54.

[0042] FIG. 5 is a flowchart showing an example of control performed by the control device 70 when the bicycle 1 is coasting. This control is performed, for example, when the bicycle 1 is traveling on flat ground after descending a slope. Referring to FIG. 5, the control starts when the first to third condition determination units 71f determine that the first, second, and third conditions are all met. Once the control starts, in step S1, the power determination unit 71e determines the power to be supplied to the motor 54 based on information about the rotation speed of the crankshaft 52 from the manual drive rotation speed calculation unit 71c and the map information described above. In the following step S2, the motor control unit 71h supplies the power determined by the power determination unit 71e to the motor 54 to drive the motor 54.

[0043] Subsequently, in step S3, the fourth condition determination unit 71g determines whether or not the fourth condition is satisfied. If the determination in step S3 is affirmative, in step S4, the first to third condition determination units 71f determine whether or not all of the first to third conditions are satisfied. If the determination in step S4 is affirmative, step S1 and subsequent steps are repeated. On the other hand, if the determination in step S4 is negative, this control ends and transitions to another control.

[0044] On the other hand, if a negative determination is made in step S3, the process proceeds to step S5, where the motor control unit 71h stops the power supply to the motor 54, or, if the power supply to the motor 54 has been stopped, continues to stop the power supply to the motor 54. In the following step S6, the first to third condition determination units 71f determine whether or not all of the first to third conditions are satisfied. If a positive determination is made in step S6, step S3 and subsequent steps are repeated. On the other hand, if a negative determination is made in step S6, this control ends and the process proceeds to another control. Note that, Drive If the manual driving force becomes equal to or greater than the first threshold while the vehicle is moving and this control ends, the motor 54 may be assisted to generate an auxiliary driving force that supplements the power that rotates the wheels 3 and 4. In this way, the auxiliary driving of the motor 54 can be smoothly performed.

[0045] Next, the reasons why the control of the motor 54 according to the present disclosure is superior will be explained. FIG. 6 is a graph showing the results of an investigation into fluctuations in various physical quantities when the motor 54 is driven using an example of the control according to the present disclosure. The graph shows the relationship between vehicle speed, manual driving force, crankshaft rotation speed, current flowing through the motor 54, and the rotation speed of the motor 54, with time plotted on the horizontal axis. In FIG. 6, the solid line represents vehicle speed, and the vertical axis represents speed. The dotted line represents manual driving force, and the vertical axis represents torque. The dashed-dotted line represents the rotation speed (cadence) of the crankshaft 52, and the vertical axis represents rotation speed. The dashed-two-dot line represents the current flowing through the motor 54, and the vertical axis represents amperes. The dashed-three-dot line represents the rotation speed of the motor 54, and the vertical axis represents rotation speed. In this control of the motor 54, when the first to fourth conditions are satisfied, a constant amount of power is supplied to the motor 54 regardless of the rotation speed of the crankshaft 52.

[0046] 6, in a state in which the vehicle speed is within a certain range (first condition is satisfied) and the manual driving force is greater than 0 and less than the first threshold value (second condition is satisfied), rotation of the crankshaft 52 is detected at time t1 (third condition is satisfied), and conditions 1 to 3 are all satisfied. As a result, power is supplied to the motor 54, and the current flowing through the motor 54 monotonically increases accordingly. At time t2, the motor 54 begins to rotate, and thereafter the rotation speed of the motor 54 monotonically increases.

[0047] The first and second conditions are met when the bicycle 1 is coasting. The third condition is met when the person lightly steps on the pedals 10, in other words, when the person indicates their intention to pedal 10. In Figure 6, time t3 indicates the timing at which power is supplied to the motor 54 under conventional control. Under conventional control, power supply to the motor 54 begins when the manual driving force reaches a certain level or greater (when the manual driving force reaches on-torque (fourth threshold)).

[0048] In Figure 6, time t1, at which power is supplied to the motor 54 under the control of the present disclosure, is much earlier than time t3, at which power is supplied to the motor under conventional control. Therefore, under this control, the motor 54 is already rotating when the person fully depresses the pedal 10 (slightly earlier than time t3). Therefore, even if the rotation speed of the crankshaft 52 (pedal 10) rises sharply in a short period of time when the person depresses the pedal 10 while the bicycle 1 is coasting, the rotation speed of the motor 54, after being slowed down by the speed reduction mechanism 57, can quickly catch up with the rotation speed of the crankshaft 52. Therefore, when the human-powered driving force reaches on-torque, the auxiliary driving force and the human-powered driving force can be quickly combined. Therefore, when the bicycle 1 is coasting, the motor 54 can quickly provide assist in line with the person's intentions, improving the responsiveness of the motor drive.

[0049] Next, we will explain why the fourth condition is necessary. Suppose bicycle 1 is stopped using a stand with rear wheel 4 raised off the ground. If crankshaft 52 rotates for some reason, the rotation of rear wheel 4 will cause vehicle speed sensor 69 to detect a vehicle speed greater than 0, satisfying conditions 1 to 3 and driving motor 54. If condition 4 does not exist, the rotational speed of motor 54, after being reduced by reduction mechanism 57, will exceed the rotational speed of crankshaft 52, and the crankshaft 52, and therefore pedals 10, will continue to rotate automatically due to the power of motor 54.

[0050] FIG. 7 is a graph showing an example of fluctuations in various physical quantities in a test conducted with the bicycle 1 using a stand and the rear wheel 4 raised when an example of the control disclosed herein was employed. In FIG. 7, the solid line again represents vehicle speed, with the vertical axis representing speed. The dotted line represents manual driving force, with the vertical axis representing torque. The dashed-dotted line represents the rotation speed of the crankshaft 52, with the vertical axis representing rotation speed. The dashed-two-dot line represents the current flowing through the motor 54, with the vertical axis representing amperes. The dashed-three-dot line represents the rotation speed of the motor 54, with the vertical axis representing rotation speed.

[0051] 7 , at time t11, the first to third conditions are satisfied, power is supplied to the motor 54, and the motor 54 begins to output power. Then, at time t12, the motor 54 begins to rotate, and thereafter, the rotation speed of the motor 54 monotonically increases. However, when the fourth condition is no longer satisfied at time t13, the supply of power to the motor 54 is stopped, and the rotation speed of the motor 54 decreases accordingly. Therefore, under the fourth condition that the value obtained by dividing the rotation speed of the motor 54 by the rotation speed of the crankshaft 52 is equal to or less than the third threshold, by setting the third threshold to a value equal to or less than the reduction ratio of the rotation speed of the motor 54, it is possible to prevent the crankshaft 52 from continuing to rotate automatically by the power of the motor 54.

[0052] As described above, bicycle 1 includes motor 54 that generates auxiliary driving force to supplement the power that rotates wheels 3 and 4 through auxiliary driving, a vehicle speed sensor (vehicle speed detection unit) 69 that detects the vehicle speed, a torque sensor (manual driving force detection unit) 59 that detects the manual driving force applied to crankshaft 52, a manual driving rotation speed detection unit 65 that detects the rotation speed of crankshaft (rotating body) 52 that rotates due to the manual driving force, and motor 54 Drive The control device 70 also includes a first condition that the vehicle speed is within a predetermined range greater than 0, a second condition that the manual driving force is less than a first threshold greater than 0, and a third condition that the rotation speed of the crankshaft 52 is equal to or greater than a second threshold greater than 0. Mukaku When the operating conditions are met, the motor 54 Drive Move.

[0053] Therefore, when the bicycle 1 is coasting, the motor 54 can be assisted in a short time in accordance with the rider's wishes, and the responsiveness of the motor drive can be improved.

[0054] The bicycle 1 may also be equipped with a Hall IC (motor rotation speed detector) 60 that detects the rotation speed of the motor 54. , drive The operating conditions may include a fourth condition that the value obtained by dividing the rotation speed of the motor 54 by the rotation speed of the crankshaft 52 is equal to or less than a third threshold value.

[0055] According to this configuration, when the vehicle speed sensor 69 detects the vehicle speed based on the rotation of the rear wheel 4, when the bicycle 1 is stopped using a stand with the rear wheel 4 raised, the crankshaft 52 can be prevented from continuing to rotate automatically due to the power of the motor 54.

[0056] Also, as explained in steps S1 and S2 of the flowchart in FIG. , drive The power supplied to the motor 54 when the operating conditions are met may be varied based on the rotation speed of the crankshaft 52.

[0057] This configuration makes it easy to adjust the rotation speed of the motor 54 based on the human driving force exerted by the person pedaling the pedals 10. For example, if the human driving force exerted by the person pedaling the pedals 10 is large, it is easy to increase the rotation speed of the motor 54. This makes it easy to further improve the responsiveness of the motor drive when the bicycle 1 is coasting.

[0058] In the first embodiment described above, the case where the power supplied to the motor 54 is varied based on the rotation speed of the crankshaft 52 has been described. However, as shown in FIG. 8, that is, the flowchart corresponding to FIG. 5 in the control of the modified example, when the first to third conditions are met and control starts, step S11 may be performed instead of step S1. Also, in step S11, the control device may determine the power to be supplied to the motor 54 based on the rate of change per unit time of the rotation speed of the crankshaft 52, instead of the rotation speed of the crankshaft 52. Then, when step S11 is completed, step S2 and subsequent steps described using the flowchart shown in FIG. 5 may be performed.

[0059] In step S11, the control device may specify the power to be supplied to the motor 54 based on the rate of change per unit time of the rotation speed of the crankshaft 52 from the manual drive rotation speed calculation unit 71c and map information that defines the correspondence between the rate of change and the power to be supplied to the motor 54. The map information may be stored in advance in the storage unit. In the map information, for example, the region of the rate of change per unit time may be divided into M regions (M is any natural number equal to or greater than 2).

[0060] In addition, in the map information, different powers may be associated with different regions. In addition, in the map information, the same power may be associated with the rate of change per unit time of the rotation speed of the crankshaft 52 within the same region. Furthermore, the power may be larger in a region where the rate of change per unit time of the rotation speed of the crankshaft 52 is larger. Or, as in the control used in the tests of FIGS. 6 and 7, , drive When the operating conditions are satisfied, the electric power supplied to the motor 54 may be constant regardless of the rotation speed of the crankshaft 52.

[0061] Also, the case where the rotating body rotated by manual driving force is crankshaft 52 has been described. However, the rotating body rotated by manual driving force may be something other than crankshaft 52, such as wheels 3 and 4, intermediate rotating shaft 57b, or force combiner 55. Also, the rotating body may have the same rotational axis as crankshaft 52, such as force combiner 55, or may have a rotational axis different from crankshaft 52, such as wheels 3 and 4 or intermediate rotating shaft 57b. Also, the first threshold value may be less than the on-torque of the power-assisted bicycle.

[0062] (Second embodiment) 9 is a plan cross-sectional view of a bicycle 101 according to a second embodiment, corresponding to FIG. 2. In the second embodiment, the same components as those in the first embodiment are designated by the same reference numerals as those in the first embodiment, and descriptions thereof will be omitted. In addition, in the second embodiment, descriptions of the same effects and modifications as those in the first embodiment will be omitted.

[0063] As shown in Figure 9, motor unit 105 of bicycle 101 is different from motor unit 5 shown in Figure 2 in that the human driving force from human power transmission body 53 is transmitted to combined force body 55 via intermediate cylinder body 62 and one-way clutch 56. Furthermore, in bicycle 101, the control device does not determine the fourth condition, and supplies power to motor 54 whenever conditions 1 to 3 are met.

[0064] The motor unit 105 is configured to perform control (so-called delay control) so that the motor 54 continues to rotate for a short period of time even after the person stops pedaling the pedals 10. In such a case, if the one-way clutch 56 were not provided, the auxiliary driving force from the motor 54 would be transmitted to the crankshaft 52, causing the pedals 10 to continue rotating on their own. Therefore, the one-way clutch 56 cuts off the auxiliary driving force from the motor 54 to prevent this force from acting on the crankshaft 52 or the pedals 10.

[0065] Furthermore, by providing a one-way clutch 56, when the bicycle 1 is stopped using a stand with the rear wheel 4 raised, even if the rotation speed of the motor 54 after being slowed down by the reduction mechanism 57 exceeds the rotation speed of the crankshaft 52, the auxiliary driving force from the motor 54 is not transmitted to the crankshaft 52, preventing the pedals 10 from continuing to rotate automatically.

[0066] FIG. 10 is a flowchart showing an example of control performed by the control device of the second embodiment when the bicycle 101 is coasting. As shown in FIG. 10, in this control, when the first to third conditions are met, the control starts, and steps S1 and S2 are completed, step S23 is performed instead of step S3. In step S23, the first to third condition determination unit 71f determines whether all of the first to third conditions are met. If the determination in step S23 is affirmative, step S1 and subsequent steps are repeated. On the other hand, if the determination in step S23 is negative, this control ends and the system transitions to another control.

[0067] As described above, in the second embodiment, the operation of the one-way clutch 56 prevents the pedals 10 from rotating uncontrollably due to the auxiliary driving force from the motor 54. Therefore, when comparing with the flow shown in FIG. 5, determining whether the fourth condition is met can be omitted. It is also possible to prevent the pedals 10 from continuing to rotate automatically when the bicycle 1 is placed on a stand with the rear wheel 4 raised off the ground, without using the one-way clutch 56. Specifically, the speed sensor 69 may be attached to the lower end of the front fork 26 (see FIG. 1) instead of to the rotation support portion of the rear wheel 4. The bicycle speed may then be detected based on the number of rotations per unit time of the front wheel 3 (see FIG. 1). This also prevents the pedals 10 from continuing to rotate uncontrollably because the speed sensor 69 does not continuously detect a speed greater than 0 when the bicycle 1 is stopped. [Explanation of symbols]

[0068] 1,101 Electrically assisted bicycle, 2 Frame, 3 Front wheel, 4 Rear wheel, 5,105 Motor unit, 6 Battery, 7 Handle, 8 Saddle, 9 Crank arm, 10 Pedal, 11 Unit case, 12 Chain, 13 Rear wheel sprocket, 26 Front fork, 51 Drive sprocket, 52 Crankshaft, 53 Human power transmission body, 54 Motor, 54a Output shaft, 54b Rotor, 55 Combined force body, 55a Large diameter gear part, 56,64 One-way clutch, 57 Reduction mechanism, 57a Small diameter gear part, 57b Intermediate rotating shaft, 59 Torque sensor, 59a Coil, 60 Hall IC, 61 Rotating member, 62 Intermediate cylinder, 63 Light shielding body, 63a Mounting part, 63b Tooth portion, 65 Manual drive rotation speed detection portion, 66 Light emitting portion, 67 Light receiving portion, 68 Optical sensor, 69 Vehicle speed sensor, 70 Control device, 71 Control portion, 71a Vehicle speed calculation portion, 71b Manual drive force calculation portion, 71c Manual drive rotation speed calculation portion, 71d Motor rotation speed calculation portion, 71e Power determination portion, 71f Third condition determination portion, 71g Fourth condition determination portion, 71h Motor control portion, 72 Memory portion, 73 Cover, 74 Vehicle speed sensor, 76: Motor drive switching element.

Claims

1. a motor that generates auxiliary driving force to supplement the power that rotates the wheels by auxiliary driving; a vehicle speed detection unit that detects a vehicle speed; a manual driving force detection unit that detects a manual driving force applied to the crankshaft; a manual-powered rotation speed detection unit that detects the rotation speed of the rotating body that is rotated by the manual drive force; and a control device that drives the motor, The driving of the motor includes an auxiliary driving that can assist the power that rotates the wheels, and a driving that cannot assist the power that rotates the wheels, the control device drives the motor when drive conditions are satisfied, the drive conditions including a first condition that the vehicle speed is within a predetermined range greater than 0, a second condition that the manual driving force is less than a first threshold greater than 0, and a third condition that the rotation speed of the rotating body is equal to or greater than a second threshold greater than 0; the first threshold value is less than the on-torque of the power-assisted bicycle, The state where the torque is less than the on-torque state is a state where the auxiliary driving force is not being generated, When the bicycle is driven without assistance, the electric power supplied to the motor is varied based on the number of revolutions of the crankshaft.

2. a motor that generates auxiliary driving force to supplement the power that rotates the wheels by auxiliary driving; a vehicle speed detection unit that detects a vehicle speed; a manual driving force detection unit that detects a manual driving force applied to the crankshaft; a manual-powered rotation speed detection unit that detects the rotation speed of the rotating body that is rotated by the manual-powered driving force; a control device that drives the motor, The driving of the motor includes an auxiliary driving that can assist the power that rotates the wheels, and a driving that cannot assist the power that rotates the wheels, the control device drives the motor when drive conditions are satisfied, the drive conditions including a first condition that the vehicle speed is within a predetermined range greater than 0, a second condition that the manual driving force is less than a first threshold greater than 0, and a third condition that the rotation speed of the rotating body is equal to or greater than a second threshold greater than 0; the first threshold value is less than the on-torque of the power-assisted bicycle, The state where the torque is less than the on-torque state is a state where the auxiliary driving force is not being generated, When the electric bicycle is driven without assistance, the current of the motor increases monotonically.

3. 3. The electrically assisted bicycle according to claim 1, further comprising a one-way clutch that interrupts a power transmission path through which human driving force is transmitted to the motor.

4. 4. The electrically assisted bicycle according to claim 1, wherein the rotating body is the crankshaft.

5. The electrically assisted bicycle according to claim 1 , wherein the rotating body is different from the crankshaft.

6. The electrically assisted bicycle according to claim 5, wherein the rotating body has the same rotation axis as the crankshaft.

7. The electrically assisted bicycle according to claim 5, wherein the rotating body has a rotation axis different from that of the crankshaft.

8. The electrically assisted bicycle according to claim 7, wherein the rotating body is the wheel.

9. a motor rotation speed detection unit that detects the rotation speed of the motor; the drive conditions include a fourth condition that a value obtained by dividing the rotation speed of the motor by the rotation speed of the crankshaft is equal to or less than a third threshold value; the third threshold value is a value equal to or less than a reduction ratio of the rotation speed of the motor; 9. An electrically assisted bicycle according to any one of claims 1 to 8.

10. 3. The electrically assisted bicycle according to claim 2, wherein the electric power supplied to the motor when the drive condition is satisfied is varied based on the rotation speed of the crankshaft.

11. The electrically assisted bicycle according to claim 1 , wherein the control device performs the auxiliary driving of the motor when the manual driving force becomes equal to or greater than the first threshold value while the motor is being driven.

12. 1. A method for controlling a motor of an electrically assisted bicycle, the motor generating an auxiliary driving force that assists in rotating a wheel, the method comprising: When drive conditions are satisfied, the drive motor is driven, the drive conditions including a first condition that the vehicle speed is within a predetermined range greater than 0, a second condition that the manual driving force applied to the crankshaft is less than a first threshold greater than 0, and a third condition that the rotation speed of a rotating body rotated by the manual driving force is equal to or greater than a second threshold greater than 0, the first threshold value is less than the on-torque of the power-assisted bicycle, The state where the torque is less than the on-torque state is a state where the auxiliary driving force is not being generated, The driving of the motor includes an auxiliary driving that can assist the power that rotates the wheels, and a driving that cannot assist the power that rotates the wheels, A method for controlling a motor of an electrically assisted bicycle, wherein the power supplied to the motor during driving without assistance is varied based on the rotation speed of the crankshaft.

13. 1. A method for controlling a motor of an electrically assisted bicycle, the motor generating an auxiliary driving force that assists in rotating a wheel, the method comprising: When drive conditions are satisfied, the drive motor is driven, the drive conditions including a first condition that the vehicle speed is within a predetermined range greater than 0, a second condition that the manual driving force applied to the crankshaft is less than a first threshold greater than 0, and a third condition that the rotation speed of a rotating body rotated by the manual driving force is equal to or greater than a second threshold greater than 0, the first threshold value is less than the on-torque of the power-assisted bicycle, The state where the torque is less than the on-torque state is a state where the auxiliary driving force is not being generated, The driving of the motor includes an auxiliary driving that can assist the power that rotates the wheels, and a driving that cannot assist the power that rotates the wheels, A method for controlling a motor of an electrically assisted bicycle, wherein the current of the motor is monotonically increased during driving when assistance is not possible.

Images