JP4451478B2 - Auxiliary power control method for battery-assisted bicycle - Google Patents

Description

  The present invention relates to an auxiliary power control method for a battery-assisted bicycle.

  An electric assist bicycle that detects the pedal effort and supplies the electric motor with an assist current according to the magnitude of the pedal effort and travels with the assistance of the assist power generated by the electric motor has been developed and has already been put into practical use. Yes.

In such a battery-assisted bicycle, the assist current supplied from the battery to the electric motor is set to a value such that the electric motor generates auxiliary power substantially equivalent to the pedaling force of the occupant. (For example, see Patent Document 1)
JP-A-5-246378

  However, in the control of the auxiliary power of the conventional battery-assisted bicycle, a specified assist current is supplied to the electric motor when the assist by the auxiliary power is unnecessary, or when the assist is necessary or less. Since the predetermined auxiliary power is generated, wasteful current consumption occurs, and there is a problem that the cruising distance per one charge of the battery does not increase.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an auxiliary power control method for a battery-assisted bicycle capable of extending a cruising distance per one charge of a battery while keeping current consumption low. It is to provide.

The present invention detects a pedaling force, supplies an assist current according to the magnitude of the pedaling force to an electric motor, and changes in a sinusoidal shape in an electrically assisted bicycle that travels with assistance from auxiliary power generated by the electric motor. In the pedal force increasing part from the bottom dead center to the top dead center of the pedaling force waveform to be supplied, a normal assist current that generates auxiliary power of approximately the same magnitude as the pedaling force is supplied, and the top dead center is exceeded and the bottom dead center is reached. In the stepping force lowering portion, the supply of the assist current is stopped, or the assist current is set to be lower than a normal set value for generating auxiliary power substantially equal to the stepping force .

  According to the present invention, in the stepping force increasing portion where the occupant applies power in the cycle of driving the battery-assisted bicycle, the normal assist current is supplied to the electric motor to obtain the necessary and sufficient normal assist power. Since the power consumption can be kept low by stopping the supply of the assist current or lowering the assist current below the normal setting value at the part where the pedaling force is lowered, The electric current can be kept low, and as a result, the cruising distance of the battery-assisted bicycle per charge of the battery can be extended.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  First, a schematic configuration of a battery-assisted vehicle 1 to which the present invention is applied will be described with reference to FIG.

  FIG. 1 is a side view of a battery-assisted bicycle 1. The battery-assisted bicycle 1 has a head pipe 2 at the front upper part of the vehicle body. A handle stem 3 is rotatably inserted into the head pipe 2. Yes. A handle 4 is attached to the upper end of the handle stem 3 so as to be offset forward. A front fork 5 is attached to the lower end of the handle stem 3, and a front wheel 6 is attached to the lower end of the front fork 5. It is pivotally supported.

  A down tube 7 extends obliquely downward from the head pipe 2 toward the rear of the vehicle body, and a seat tube 8 is erected obliquely upward from the rear end portion of the down tube 7 that extends substantially horizontally toward the rear of the vehicle body. ing. A retractable saddle 10 is supported on the upper end of a seat post 9 fitted and held in the seat tube 8 so as to be movable up and down so that the height can be adjusted.

  On the other hand, a power unit 11 is disposed at a substantially central lower portion of the vehicle body. The power unit 11 is configured by arranging a driving system using human power (stepping force) and an auxiliary power system using an electric motor 12, and synthesizes and outputs a passenger's human power (stepping force) and auxiliary power. The crankshaft 13 is rotatably supported. Cranks 14 are attached to the left and right sides of the crankshaft 13, and pedals 15 are rotatably supported at end portions of the respective cranks 14. The periphery of the connecting portion between the down tube 7 and the seat tube 8 and a part of the power unit 11 are covered with a resin cover 16. Further, the power unit 11 is provided with a controller 17 for controlling the output (auxiliary power) of the electric motor 12 in accordance with the magnitude of human power (the occupant's stepping force input to the pedal 15). Here, the output (auxiliary power) of the electric motor 12 is controlled by controlling the assist current supplied to the electric motor 12.

  A pair of left and right chain stays 18 extend substantially horizontally at the rear of the power unit 11, and the rear end of the chain stay 18 and the upper end of the seat tube 8 are connected by a pair of left and right seat stays 19. ing. A rear wheel 20 is rotatably supported at a connecting portion between the rear end of the chain stay 18 and the seat stay 19, and a part of the rear wheel 20 is covered with a rear fender 21.

  A wheel sprocket 22 is bound to the rear wheel 20, and an endless chain 23 is wound between the wheel sprocket 22 and a drive sprocket (not shown) provided in the power unit 11.

  In the battery-assisted bicycle 1 according to the present embodiment, a battery 24 is detachably mounted in a space below the saddle 10 and surrounded by the seat tube 8 and the rear fender 21. The battery 24 is attached and detached along the seat tube 8 in a state where the saddle 10 is flipped up to avoid interference with the saddle 10.

  Next, the power transmission path in the power unit 11 will be described based on the block diagram shown in FIG.

  When the occupant strokes the pedal 15, the pedal force (human power) is transmitted to the resultant shaft 26 via the crankshaft 13 and the one-way clutch 25, and the pedal force and the vehicle speed are not shown on the transmission path. Are detected by vehicle speed sensors, and their detection signals are input to the controller 17.

Then, the controller 17 calculates predetermined auxiliary power (assist force) based on various signals (stepping force signal, vehicle speed signal) input thereto and various data stored in the memory 27, and performs control corresponding to the auxiliary power. A signal (output instruction signal) is output to the electric motor 12.

Auxiliary dynamic force the electric motor 12 generates is transmitted through a reduction gear 28 and the one-way clutch 29 to the resultant force shaft 26, force chain 23, transmitted to the rear wheel 20 via the one-way clutch 30 to the transmission mechanism 31 Is done.

  Next, the auxiliary power control method which is the gist of the present invention will be described with reference to FIGS. In the auxiliary power control method according to the present embodiment, a normal assist current is supplied to the pedaling force increasing portion from the bottom dead center to the top dead center exceeding the top dead center. In the stepping force descending portion until reaching the dead point, the supply of the assist current is stopped or the assist current is set lower than a normal set value.

  The auxiliary power control method will be specifically described. FIG. 3 is a flowchart showing the control procedure of the auxiliary power, and FIG. 4 is a diagram showing temporal changes in the pedaling force, the auxiliary power, and the resultant force (= stepping force + auxiliary power).

  When the occupant starts rowing the pedal 15 of the battery-assisted bicycle 1 at time to shown in FIG. 4, the pedaling force changes in a sine wave shape as shown in FIG. 4A, but in the control method according to the present embodiment, A normal assist current is supplied to the electric motor 12 in the pedal force increasing portion from the bottom dead center to the top dead center (time t1 to t2, t3 to t4,... In the stepping force descending portion (time t2 to t3, t4 to t5,... In FIG. 4) from the top dead center to the bottom dead center, the supply of the assist current is stopped or the assist current is set to be lower than the normal set value. I try to set it low.

  Therefore, as shown in FIG. 4B, normal auxiliary power is generated in the pedal force increasing portion (time t1 to t2, t3 to t4,...), And the resultant force (= stepping force + auxiliary power) shown in FIG. ), The battery-assisted bicycle 1 is driven to run.

  On the other hand, as shown in FIG. 4 (b), in the pedal force lowering portion (time t2 to t3, t4 to t5,...), The supply of the assist current from the battery 24 to the electric motor 12 is stopped and the auxiliary power is cut. Or, as indicated by the broken line, the auxiliary power is set lower than the normal value. In FIG. 4C, the broken line indicates the resultant force when the assist current is set lower than the normal value, and the resultant force when the auxiliary power is completely cut is equal to the pedaling force shown in FIG.

  Thus, the processing shown in FIG. 3 is performed in the main loop of the motor control program built in the controller 17.

  That is, the current pedaling force is detected (step S11), and it is determined whether or not the detected current pedaling force is equal to or more than the previously detected pedaling force and the state continues for a predetermined time (step S12). If the determination result in step S12 is YES, the pedaling force is in the pedaling force increasing portion (time t1 to t2, t3 to t4,... In FIG. 4) in the pedaling force waveform, so that the electric motor 12 has a normal assist current. Energized (step S13), normal auxiliary power is generated (see FIG. 4B), and the current pedaling force is stored for the next comparison (step S14).

  On the other hand, if the determination result in step S12 is NO, it is determined whether or not a state where the current pedaling force is smaller than the previous pedaling force has continued for a certain period of time (step S15), and the determination result is NO. The current state is maintained (step S16), and when the determination result is YES, the pedaling force is in the pedaling force descending portion (time t2 to t3, t4 to t5,... The supply of the assist current from 24 to the electric motor 12 is stopped and the auxiliary power is cut, or the auxiliary power is set lower than the normal value as shown by a broken line in FIG. 4B (step S17). ).

  Thus, according to the auxiliary power control method according to the present embodiment, the normal assist current is supplied to the electric motor 12 in the stepping force increasing portion where the occupant applies force in the cycle of driving the battery-assisted bicycle 1. While necessary and sufficient normal auxiliary power can be obtained, it is possible to stop the supply of assist current or to lower the current consumption by lowering the assist current below the normal setting value in the stepping force descending part that pulls out the force. As a result, a reasonable current consumption is possible, and the current consumption can be kept low as a whole. As a result, the cruising distance of the battery-assisted bicycle 1 per charge of the battery 24 can be extended.

1 is a side view of a battery-assisted bicycle according to an embodiment of the present invention. It is a block diagram which shows the power transmission path | route in the power unit of the said battery-assisted bicycle. It is a flowchart which shows the auxiliary power control procedure which concerns on Embodiment 1 of this invention. It is a figure which shows the time change of the treading force at the time of using the auxiliary power control method which concerns on the said embodiment, auxiliary power, and resultant force (= pedaling force + auxiliary power).

Explanation of symbols

1 battery-assisted bicycle 11 power unit 12 electric motor 17 controller 24 battery

Claims (1)

In an electrically assisted bicycle that detects pedaling force, supplies an assist current according to the magnitude of the pedaling force to the electric motor, and travels with assistance from auxiliary power generated by the electric motor.
In the pedal force increasing part from the bottom dead center to the top dead center of the pedal force waveform that changes in a sine wave shape, a normal assist current that generates auxiliary power of approximately the same magnitude as the pedal force is supplied, and the bottom dead center exceeds the top dead center. The electric assist is characterized in that the supply of the assist current is stopped at the portion where the pedal force is reduced to the point, or the assist current is set lower than a normal set value for generating auxiliary power substantially equal to the pedal force. Bicycle auxiliary power control method.

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