Electric assistance system and electrically assisted vehicle

Patent metadata

Field	Value
Publication number	US-2019299797-A1
Application number	US-201916443923-A
Country	US
Kind code	A1
Filing date	Jun 18, 2019
Priority date	Dec 28, 2016
Publication date	Oct 3, 2019
Grant date	—

Abstract

An electric assistance system used in an electrically assisted vehicle provided with a pedal includes a crankshaft rotatable by human power of a rider applied to the pedal, a torque sensor that outputs a torque signal in accordance with a magnitude of a torque generated at the crankshaft, an electric motor that generates an assist power that assists the human power of the rider, an acceleration sensor that outputs an acceleration signal in accordance with a current acceleration in a travel direction of the electric assist vehicle, and a controller that receives the torque signal and the acceleration signal and determines a magnitude of the assist power to be generated by the electric motor. The controller calculates a target acceleration from the torque signal based on a rule prepared in advance, and determines the magnitude of the assist power to be generated by the electric motor such that a deviation between the target acceleration and the current acceleration is decreased.

First claim

What is claimed is:

1 . An electric assist system for an electric assist vehicle including a pedal, the electric assist system comprising:
a crankshaft rotatable by human power of a rider applied to the pedal; a torque sensor that outputs a torque signal in accordance with a magnitude of a torque generated at the crankshaft; an electric motor that generates an assist power that assists the human power of the rider; an acceleration sensor that outputs an acceleration signal in accordance with a current acceleration in a travel direction of the electric assist vehicle; and a controller configured or programmed to receive the torque signal and the acceleration signal and to determine a magnitude of the assist power to be generated by the electric motor; wherein the controller is configured or programmed to calculate a target acceleration from the torque signal based on a rule prepared in advance, and to determine the magnitude of the assist power to be generated by the electric motor such that a deviation between the target acceleration and the current acceleration is decreased.

2 . The electric assist system of claim 1 , wherein the controller is configured or programmed to perform PID control to determine the magnitude of the assist power to be generated by the electric motor to decrease the deviation.

3 . The electric assist system of claim 2 , wherein
when a current deviation at a current time t is represented as E(t), and feedback gains of a proportional element, a differential element, and an integration element of the assist power control system are respectively represented as Kp, Kd, and Ki, the controller is configured or programmed to determine a motor torque Fm, corresponding to the assist power to be generated, by the electric motor by:

Fm


(
t
)

=

Kp
×

e


(
t
)

+

Ki
×

∫
0
t



e
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(
τ
)


d
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
τ

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+

Kd
×

de
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(
t
)

dt

.

Expression
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1

4 . The electric assist system of claim 1 , wherein the controller is configured or programmed to determine the magnitude of the assist power to be generated by the electric motor such that the deviation is closer to 0.

5 . The electric assist system of claim 1 , wherein the controller is configured or programmed to store, in advance, a table associating a command value of an electric current in the electric motor and a magnitude of a motor torque corresponding to the assist power to be generated by the electric motor to each other, and to refer to the table to determine the command value of the electric current required to generate the motor torque.

6 . The electric assist system of claim 4 , wherein the controller is configured or programmed to store, in advance, a table associating a command value of an electric current in the electric motor and a magnitude of a motor torque to each other for each of ranges of magnitudes of the deviation, and to refer to the table to determine the command value of the electric current required to generate the motor torque.

7 . The electric assist system of claim 2 , wherein
when a current deviation at current time t is represented as E(t), and feedback gains usable to determine a command value of an electric current from a proportion term, a differential term and an integration term regarding a residual deviation are respectively represented as Kp′, Kd′ and Ki′, the controller is configured or programmed to determine the command value Im, of the electric current in the electric motor, by:

Im


(
t
)

=

Kp
′

×

e


(
t
)

+

Ki
′

×

∫
0
t



e


(
τ
)


d


Assignees

• Yamaha Motor Co Ltd

Inventors

• Hasumi Mitsuharu

Classifications

• B60L2240/16

  longitudinal · CPC title

• B60L2240/423

  Torque · CPC title

• B60L2200/12

  Bikes · CPC title

• B60L50/20

  using propulsion power generated by humans or animals · CPC title

• B60L15/2036

  Electric differentials, e.g. for supporting steering vehicles · CPC title