Electrically assisted bicycle

Abstract

To provide an electric assist bicycle capable of suitably shifting to a power saving mode.SOLUTION: An electric assist bicycle according to one aspect of the present invention includes a crank that is connected to a crank shaft and to which a pedaling force is applied by a rider via a pedal, a drive unit that drives a wheel, a determination unit that determines whether or not the rider is in a predetermined riding state, and a control unit that, in response to a determination by the determination unit as to whether or not the rider is in the predetermined riding state, A power supply control unit configured to supply power to the drive unit in one of a first power supply mode and a second power supply mode in which power consumption is smaller than that in the first power supply mode, The predetermined riding state is a state in which a vehicle speed is zero and the driver is riding in the vehicle.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an electrically assisted bicycle. [Background technology]

[0002] There is known technology for conserving the power consumption of batteries used as the power source for electrically assisted bicycles. Patent Document 1 discloses an electric motor bicycle that performs energy-saving operation when the integrated value of a timer that starts when the pedal force and bicycle speed signals both fall below a certain value reaches or exceeds a certain value, in order to prevent performance degradation due to battery exhaustion and complete discharge. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 6-255563 Summary of the Invention [Problem to be solved by the invention]

[0004] In the technology described in Patent Document 1, an electrically assisted bicycle switches to power-saving mode when either or both of the pedal force and bicycle speed fall below a predetermined threshold value for a certain period of time. Because the power supply mode switches to energy-saving mode only when the bicycle is stopped, even when the bicycle is temporarily stopped, such as waiting at a traffic light, the power supply mode can be activated. This can lead to inconveniences, such as unnecessary switching between normal mode, which is the normal power supply state when assisted, and power-saving mode.

[0005] An object of the present invention is to provide an electrically assisted bicycle that can suitably switch to a power saving mode. [Means for solving the problem]

[0006] An electrically assisted bicycle according to one embodiment of the present invention comprises a crank connected to a crankshaft to which a rider applies pedal force via pedals; a drive unit that drives the wheels; a determination unit that determines whether the rider is in a predetermined riding state; and a power supply control unit that supplies power to the drive unit in either a first power supply mode or a second power supply mode that consumes less power than the first power supply mode, depending on the determination by the determination unit of whether the rider is in the predetermined riding state, wherein the predetermined riding state is a state in which the vehicle speed is 0 and the rider is riding. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide an electrically assisted bicycle that can suitably switch to a power saving mode. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic diagram showing the overall configuration of an electrically assisted bicycle according to an embodiment of the present invention; [Figure 2] 1 is a schematic cross-sectional view showing the configuration of a crankshaft and the area around the crankshaft of an electrically assisted bicycle according to an embodiment of the present invention. [Figure 3] 2 is a block diagram showing the functional configuration of a control unit of the electrically assisted bicycle according to one embodiment of the present invention. FIG. [Figure 4] 5 is a diagram for explaining a first torque threshold value and a second torque threshold value of the torque applied to the crankshaft in an electrically assisted bicycle according to one embodiment of the present invention. FIG. [Figure 5] 4 is a flowchart showing the processing executed by the control unit of the power-assisted bicycle according to one embodiment of the present invention. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The following embodiments are examples for embodying the technical concept of the invention, and the present invention is not limited to the following configurations and methods. In the drawings, the same components are given the same reference numerals, and redundant description may be omitted. The size and positional relationship of members shown in the drawings may be exaggerated to facilitate understanding of the invention. In the drawings shown below, directions may be indicated by the X-axis, Y-axis, and Z-axis. The X-axis, Y-axis, and Z-axis are mutually orthogonal directions.

[0010] <Configuration of the electrically assisted bicycle according to the embodiment> The configuration of an electrically power assisted bicycle according to an embodiment will be described with reference to Figures 1 and 2. Figure 1 is a schematic diagram showing the overall configuration of an electrically power assisted bicycle 1 according to an embodiment of the present invention. Figure 2 is a schematic cross-sectional view showing the crankshaft 5 and the configuration around the crankshaft 5 of an electrically power assisted bicycle 1 according to an embodiment of the present invention. Figure 2 shows a cross section of the crankshaft 5 and the configuration around the crankshaft 5. This cross section is a cross section that includes the central axis 5C of the crankshaft 5 along the direction in which the crankshaft 5 extends, for example, a cross section parallel to the XZ plane.

[0011] In the example of Figure 1, the electrically assisted bicycle 1 includes a crank 2 to which a pedaling force is applied by the rider, a drive unit 3 that drives a front wheel 13, a control unit 4 that performs assist control that controls the operation of the drive unit 3 in accordance with the pedaling force applied to the crank 2, a pair of pedals 6, an operating unit 7, a sprocket 8, and a chain 9. The crank 2 is connected to a crankshaft 5. The electrically assisted bicycle 1 has a body 10 that includes a frame body 11, a front fork 12, a front wheel 13, a rear wheel 14, handlebars 15, a saddle 16, a battery 17, a brake 18, and a brake operating unit 19.

[0012] The power-assisted bicycle 1 can assist the rider in driving the crank 2 by generating an output from the drive unit 3 in accordance with the torque generated in the crank shaft 5 by the pedaling force applied to the crank 2 .

[0013] Each component of the power-assisted bicycle 1 will be described below.

[0014] The cranks 2 are connected to the frame body 11 so as to be rotatable about crank shafts 5. Pedals 6 are rotatably connected to each of the pair of left and right cranks 2. The rider can apply a pedaling force to the cranks 2 via the pedals 6.

[0015] The control unit 4 is an electric or electronic circuit including a processor, memory, an input / output interface, etc. The processor executes control processes including various arithmetic operations. The memory includes a read-only memory (ROM) that stores programs used in the operation of the processor, and a random access memory (RAM) used as a work area for the processor. The memory may include a hard disk drive (HDD) or a solid state drive (SSD) that stores various data or programs. The input / output interface connects the operation unit 7 or input / output devices such as various sensors to the control unit 4.

[0016] The control unit 4 executes various processes by executing command codes stored in a memory or by circuit design for a special purpose, thereby realizing various functions such as assist control and self-propelled control by the control unit 4. The control unit 4 is also connected to the brake operation unit 19 and the operation unit 7 so as to be able to communicate with them via wire or wirelessly. The control unit 4 can receive operations by the driver via the brake operation unit 19 and the operation unit 7.

[0017] In assist control, the control unit 4 operates the drive unit 3 and controls the output of the drive unit 3 in accordance with the torque of the crankshaft 5 detected by the torque sensor 20. On the other hand, in self-propelled control, the control unit 4 operates the drive unit 3 and controls the output of the drive unit 3 so that the power-assisted bicycle 1 travels under predetermined acceleration conditions, deceleration conditions, traveling speed, etc., regardless of the torque of the crankshaft 5 detected by the torque sensor 20. It is preferable that the traveling speed of the power-assisted bicycle 1 during self-propelled control be 6 km / hour or less.

[0018] The operation unit 7 is a part that accepts operations by the rider on the power-assisted bicycle 1. The operation unit 7 shown in FIG. 1 includes an operation panel located on the handlebars 15. However, the operation unit 7 is not limited to being located on the handlebars 15, and may be located on a part other than the handlebars 15, such as the frame body 11. The operation unit 7 may also be a mobile terminal such as a smartphone or mobile phone that is capable of communicating with the control unit 4, and does not necessarily have to be located on the power-assisted bicycle 1.

[0019] The operation unit 7 may include a power button for turning on or off the power of the control unit 4, etc., a switch button for manually starting, ending or switching the strength of assist control, and a display unit for displaying various information such as the remaining battery level. The operation unit 7 may also include operating components other than buttons, such as switches. Furthermore, the operation unit 7 may be configured as a touch panel that is integrated with the display unit and allows touch operation.

[0020] A sprocket 8 is fixed to the crankshaft 5. A chain 9 is stretched between the sprocket 8 and a hub 14a of a rear wheel 14. The chain 9 transmits pedaling force from the crankshaft 5 to the hub 14a of the rear wheel 14.

[0021] A battery 17 is attached to the frame body 11. A lithium-ion battery, a nickel-metal hydride battery, or the like can be used as the battery 17. A drive unit 3 that operates on power supplied from the battery 17 is arranged in the form of an in-wheel motor on the wheel axle 13a of the front wheel 13. A rare earth permanent magnet motor such as a high-speed brushed toothed wheel geared motor, a low-speed brushed motor, or a low-speed brushless motor can be used as the drive unit 3. In addition, the drive unit 3 shown in FIG. 1 has a built-in Hall element that detects the rotation angle of the front wheel 13.

[0022] In the electrically assisted bicycle 1, torque generated in the crankshaft 5 by the pedaling force applied to the crank 2 is detected by the torque sensor 20, and an output corresponding to the detected torque is generated by the drive unit 3. The electrically assisted bicycle 1 can assist the rider in driving the crank 2 with the output of the drive unit 3.

[0023] The position where the drive unit 3 is disposed is not limited to the front wheel 13. The drive unit 3 may be disposed on at least one of the front wheel 13, the rear wheel 14, or a part of the electrically assisted bicycle 1 other than the wheels. The wheel driven by the drive unit 3 may be the front wheel 13 or the rear wheel 14. The means for transmitting the driving force from the drive unit 3 may be direct or indirect, and may be changed as appropriate depending on the position of the drive unit 3.

[0024] The brakes 18 are mechanisms for slowing down or stopping the rotation of the wheels. The brakes 18 include a front wheel brake 18a that slows down or stops the rotation of the front wheels 13, and a rear wheel brake 18b that slows down or stops the rotation of the rear wheels 14.

[0025] The brake operating unit 19 is a part that receives driver operations on the brakes 18. The brake operating unit 19 shown in Fig. 1 includes a front wheel brake lever that operates to activate or deactivate the front wheel brakes 18a, and a rear wheel brake lever that operates to activate or deactivate the rear wheel brakes 18b.

[0026] In FIG. 2, the torque sensor 20 is a magnetostrictive torque sensor disposed within the accommodation portion 2a and attached to the frame body 11. The torque sensor 20 includes a housing 21, a pair of bearings 22, a magnetostrictive shaft 23, magnetostrictive foil 24, and a pair of coils 25. The housing 21 is fixed within the accommodation portion 2a. The pair of bearings 22 rotatably support the magnetostrictive shaft 23 within the housing 21. A crankshaft 5 is fixed concentrically to one end of the magnetostrictive shaft 23 in the X direction, and a sprocket 8 is fixed concentrically to the other end of the magnetostrictive shaft 23 in the X direction. The magnetostrictive foil 24 contains a magnetic material. The magnetostrictive foil 24 is provided on the outer circumferential surface of the magnetostrictive shaft 23. The pair of coils 25 are disposed within the housing 21 so as to surround the magnetostrictive shaft 23.

[0027] In the torque sensor 20, when a pedaling force is applied to the crankshaft 5 via the crank 2, the magnetostrictive foil 24 is twisted, causing a change in the magnetic permeability of the magnetostrictive foil 24 and a change in the inductance induced in the pair of coils 25. As a result, the amount of change in inductance corresponding to the pedaling force is output to the control unit 4 via the cable 26 as the torque generated in the crankshaft 5.

[0028] <Functional configuration of control unit 4> 3 is a block diagram showing the functional configuration of the control unit 4 of an electrically assisted bicycle 1 according to one embodiment of the present invention. The control unit 4 includes a determination unit 41 and a power supply control unit 42. The control unit 4 detects, with the torque sensor 20, the torque generated in the crank shaft 5 due to the pedaling force applied to the crank 2, and obtains the value of the detected torque from the torque sensor 20.

[0029] The determination unit 41 determines whether or not the rider of the power-assisted bicycle 1 is in a predetermined riding state. When the torque applied to the crankshaft 5 is equal to or greater than the first torque threshold and equal to or less than the second torque threshold, the determination unit 41 determines that the rider is in the predetermined riding state.

[0030] The "predetermined riding state" is a state in which the vehicle speed of the power-assisted bicycle 1 is 0 and the rider is riding, and may be, for example, a state in which the rider has one foot on one of the pair of pedals 6. In other words, the predetermined riding state does not have to be a state in which the power-assisted bicycle 1 is in motion, but may also be a state in which the rider has one foot on the pedal 6 and the other foot on the ground, such as when waiting at a traffic light.

[0031] The first torque threshold is set to a value that can exclude, for example, weak torque values ​​that may be detected due to unit errors in the components of the power-assisted bicycle 1. The second torque threshold is set to a value that exceeds the torque value detected in a predetermined riding state, for example, when the rider has one foot on the pedal 6 of the power-assisted bicycle 1 and the other foot on the ground, but is less than the torque value detected immediately after the rider steps on the pedal 6 to start riding the power-assisted bicycle 1.

[0032] In a predetermined riding state, a torque equal to or greater than the first torque threshold and equal to or less than the second torque threshold is detected from the torque sensor 20. In other words, when the rider is in the predetermined riding state, the torque applied to the crankshaft 5 is equal to or greater than the first torque threshold and equal to or less than the second torque threshold.

[0033] The power supply control unit 42 supplies power to the drive unit 3 in either a first power supply mode or a second power supply mode that consumes less power than the first power supply mode, depending on the riding state of the driver. When the time period during which the driver is in a predetermined riding state continues for a first predetermined time, the power supply control unit 42 shifts the power supply mode from the first power supply mode to the second power supply mode. Note that the first predetermined time may be set in advance or may be set based on an input to the operation unit 7. The first predetermined time may be, for example, five minutes, but is not limited to this and may be any time that can be set.

[0034] The first power supply mode is also called the normal mode, and is a power supply mode in which, for example, normal assist control is performed while the electrically assisted bicycle 1 is traveling. The second power supply mode is also called the power saving mode, and is a power supply mode in which, for example, power supply to the operation unit 7 is limited and power supply to electrical components such as lighting equipment attached to the electrically assisted bicycle 1 is stopped, and the control unit 4, operation unit 7, etc. are placed in a standby state in which their functions are kept to a minimum.

[0035] Here, the first and second torque thresholds of the torque F applied to the crankshaft 5 will be explained using Fig. 4. Fig. 4 is a diagram for explaining the first and second torque thresholds of the torque F applied to the crankshaft in an electrically assisted bicycle according to one embodiment of the present invention. In the graph shown, the vertical axis represents the magnitude of the torque F, and the horizontal axis represents time. In the figure, th1 represents the first torque threshold, th2 represents the second torque threshold, and t1 represents the first predetermined time.

[0036] When the rider changes from a state in which the rider has no feet on the pair of pedals 6 to a predetermined riding state, that is, when the rider places one foot on the pedal 6 and the other foot on the ground, the torque F changes as shown in the figure. When the torque F remains in a state of being equal to or greater than the first torque threshold and equal to or less than the second torque threshold for a first predetermined time, the power supply control unit 42 transitions the power supply mode from the first power supply mode to the second power supply mode.

[0037] When the power supply mode of an electrically assisted bicycle is changed based on a single torque threshold, as in conventional technology, there is a possibility that the bicycle will enter power-saving mode even when the bicycle is about to resume riding immediately, such as when waiting at a traffic light. This can result in unnecessary cycling between normal and power-saving modes, which can lead to problems such as repeated power supply and power outages to the operating unit.

[0038] In the electrically power assisted bicycle 1 according to this embodiment, the transition from the first power supply mode, which is the normal mode, to the second power supply mode, which is the power saving mode, is performed at a timing based on the first torque threshold, the second torque threshold, and the first predetermined time. Therefore, the power supply mode can be changed depending on whether the rider is riding the electrically power assisted bicycle 1 or a predetermined riding state, such as waiting at a traffic light.

[0039] More specifically, when the rider is in a predetermined riding state, that is, when the speed of the electrically power assisted bicycle 1 is 0 and the torque F is equal to or greater than the first torque threshold and equal to or less than the second torque threshold, the electrically power assisted bicycle 1 waits for a first predetermined time before transitioning to the power saving mode. Because the determination that the rider is in the predetermined riding state may be an erroneous determination, the electrically power assisted bicycle 1 transitions to the second power supply mode after the first predetermined time has elapsed.

[0040] <Processing by the control unit> 5 is a flow diagram showing the processing executed by the control unit 4 of the power-assisted bicycle 1 according to one embodiment of the present invention. The illustrated flow diagram shows an example of the power supply mode transition processing while the power-assisted bicycle 1 is traveling or stopped.

[0041] The control unit 4 detects the vehicle speed v of the power-assisted bicycle 1 (step S101). The power-assisted bicycle 1 may be equipped with a vehicle speed detection means (not shown). The vehicle speed detection means may use a Hall element that detects the rotation angle of the front wheel 13 as a rotation sensor, and may detect the vehicle speed v using the rotation sensor. Alternatively, the vehicle speed v may be calculated by integrating the acceleration detected by an acceleration sensor.

[0042] If the vehicle speed v of the power-assisted bicycle 1 is 0 (YES in step S102), the control unit 4 detects the state of at least one of the operation unit 7 and the brake 18 (step S103). The state of the operation unit 7 may be the presence or absence of an input operation to the operation unit 7. Furthermore, the state of the brake 18 may be the presence or absence of operation of the brake lever. If the vehicle speed v of the power-assisted bicycle 1 is not 0 (NO in step S102), the control unit 4 continues assist control of the power-assisted bicycle 1 (step S109).

[0043] When at least one of the operating unit 7 and the brake 18 is not operated (YES in step S104), the control unit 4 detects the torque F applied to the crankshaft 5 by the torque sensor 20 (step S105).

[0044] If the torque F applied to the crankshaft 5 is equal to or greater than the first torque threshold and equal to or less than the second torque threshold, the determination unit 41 determines that the driver is in a predetermined riding state (YES in step S106), and counts the elapsed time t (step S107).

[0045] Then, if the vehicle speed v of the electrically assisted bicycle 1 is 0, at least one of the operation unit 7 and the brake 18 is not being operated, the torque F remains equal to or greater than the first torque threshold and equal to or less than the second torque threshold, and the elapsed time t continues for the first predetermined time t1 (NO in step S108), the power supply control unit 42 transitions the power supply mode from the first power supply mode to the second power supply mode (step S110).If the elapsed time t does not continue for the first predetermined time t1 (YES in step S108), the control unit 4 continues assist control of the electrically assisted bicycle 1 (step S109).

[0046] Furthermore, if the torque F applied to the crankshaft 5 is less than the first torque threshold value (NO in step S111), the control unit 4 determines that a rider is not riding the power-assisted bicycle 1, and counts the elapsed time t (step S112). Then, when the time t0 has elapsed (NO in step S112), the power supply control unit 42 transitions the power supply mode from the first power supply mode to the second power supply mode (step S110).

[0047] The time t0 is a third predetermined time used to determine whether to switch from the first power supply mode to the second power supply mode when the rider is not riding the power-assisted bicycle 1. Therefore, the time t0 may be set shorter than the first predetermined time t1 when the rider is in a predetermined riding state. This allows the power consumption of the battery 17 to be managed appropriately.

[0048] In addition, if the torque F is greater than or equal to the first torque threshold in step S111 (YES in step S111), the control unit 4 determines that the electric assist bicycle 1 is in motion because the torque F exceeds the second threshold, and continues assist control of the electric assist bicycle 1 (step S109).

[0049] Furthermore, when the rider is not riding the power-assisted bicycle 1 and the elapsed time t does not continue beyond time t0 (YES in step S113), the control unit 4 continues the assist control of the power-assisted bicycle 1 (step S109).

[0050] When the power supply mode is the second power supply mode and the counted elapsed time t continues for the second predetermined time t2 (YES in step S114), the power supply control unit 42 stops power supply to the electrically assisted bicycle 1 (step S115). If the counted elapsed time t does not continue for the second predetermined time t2 (NO in step S114), the control unit 4 repeats the processes of steps S110 and S114.

[0051] <Modification> In the electrically assisted bicycle 1 according to this embodiment, whether or not the rider is in a predetermined riding state is determined based on the torque F applied to the crankshaft 5, as described above. Below, a modified method for determining whether or not the rider is in a riding state will be described.

[0052] A sensor may be provided on a component of the electrically assisted bicycle 1 that comes into contact with the rider, and the riding state of the rider may be determined based on the detection of the sensor. The component that comes into contact with the rider may be, for example, any of the pedals 6, the handlebars 15, and the saddle 16. A load sensor separate from the torque sensor 20 described above may be attached to the pedals 6 as a sensor for detecting the load on the pedals 6. A sensor for detecting the grip strength of the rider may also be provided on the handlebars 15. Furthermore, a sensor for detecting the load of the rider may be provided on the saddle 16.

[0053] As another example, an air pressure sensor may be provided on the wheel to determine whether or not the rider is riding. As yet another example, a strain sensor may be attached to the frame body 11 or an axle (not shown) to detect changes in strain in the body 10 when the rider is riding and when the rider is dismounting. Also, a tilt sensor may be provided to detect the tilt of the electrically assisted bicycle 1, and the tilt of the electrically assisted bicycle 1 in the +X or -X direction may be detected.

[0054] Using the various detection means described above, it is possible to determine whether the rider is in a specified riding state or not, since there are differences in the load and inclination of the body detected when the electric assist bicycle 1 is in motion and when the rider is in a specified riding state.

[0055] As another modification, the power-assisted bicycle 1 can remain in the first power supply mode, which is the normal mode, when the torque applied to the crankshaft 5 is equal to or greater than the first torque threshold and equal to or less than the second torque threshold.

[0056] <Effects> As described above, in the power-assisted bicycle 1 according to this embodiment, the transition from the first power supply mode, which is the normal mode, to the second power supply mode, which is the power-saving mode, is performed at a timing based on the first torque threshold, the second torque threshold, and the first predetermined time t1. Therefore, the power supply mode can be changed depending on whether the rider is riding the power-assisted bicycle 1 or is in a predetermined riding state, such as waiting at a traffic light.

[0057] Therefore, the power-assisted bicycle 1 according to this embodiment can provide a power-assisted bicycle that can suitably switch to the power-saving mode.

[0058] Although the preferred embodiment has been described above in detail, the present invention is not limited to the above-described embodiment, and various modifications and substitutions can be made to the above-described embodiment without departing from the scope of the claims. For example, various materials, shapes, and configurations can be applied to the components of the electrically power-assisted bicycle 1, without being limited to the materials, shapes, and configurations described above. [Explanation of symbols]

[0059] 1. Electrically assisted bicycle 2 cranks 3 Drive unit 4. Control Unit 5 crankshaft 6 pedals 7 Control section 10. Body 13 Front wheel 14 Rear wheel 41 Judgment section 42 Power supply control unit F Torque

Claims

1. a crank connected to the crankshaft and to which a pedal force can be applied by the driver via a pedal; a drive unit that drives the wheels; a determination unit that determines whether the driver is in a predetermined riding state; a power supply control unit that supplies power to the drive unit in either a first power supply mode or a second power supply mode in which power consumption is lower than that in the first power supply mode, depending on whether the determination unit determines whether the vehicle is in the predetermined riding state; and Equipped with The predetermined riding state is a state in which the vehicle speed is 0 and the driver is riding in the vehicle. Electric assist bicycle.

2. the power supply control unit transitions the power supply mode from the first power supply mode to the second power supply mode when the time during which the driver is in the predetermined riding state continues for a first predetermined time. The electrically assisted bicycle according to claim 1.

3. the determination unit determines that the driver is in a predetermined riding state when a torque value applied to the crankshaft is equal to or greater than a first torque threshold and equal to or less than a second torque threshold. The electrically assisted bicycle according to claim 1.

4. the second torque threshold value is a value less than the torque value detected immediately after the rider depresses the pedal to start riding the electrically assisted bicycle, The electrically assisted bicycle according to claim 3.

5. an operation unit that receives operations for the electrically assisted bicycle; In the second power supply mode, power supply to the operation unit is limited. The electrically assisted bicycle according to claim 1.

6. the power supply control unit stops power supply to the electrically assisted bicycle when the second power supply mode continues for a second predetermined time. The electrically assisted bicycle according to claim 1.

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