Fluid-pressure and analogous brake systems – Speed-controlled – Regenerative brakes
Patent
1996-11-12
1998-11-24
Poon, Peter M.
Fluid-pressure and analogous brake systems
Speed-controlled
Regenerative brakes
303 3, 318376, 188156, B60T 1374
Patent
active
058398007
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to an electric automobile which runs by driving wheels with an electric motor, and especially to a braking control system for an electric automobile so that braking of a vehicle is controlled relying upon regenerative braking by a motor.
BACKGROUND ART
In recent years, electric automobiles each of which drives wheels by an electric motor instead of an internal combustion engine have attracted an increasing interest from the viewpoint of prevention of air pollution and reduction of vehicle noise.
These electric automobiles easily allow so-called regenerative braking. This regenerative braking can be performed by limiting a supply of electric power to a drive motor and converting the motor into a power-generating state. At this time, a load is applied to each drive wheel so that, while braking the drive wheel, rotational energy of the drive wheel can be recovered as electric energy.
When a driver operates a brake pedal or the like to command braking in such an electric automobile, a braking force (regenerative braking force) a s a result of regenerative braking by a motor is applied in addition to a braking force (mechanical braking force) by a mechanical brake (mechanical brake system) which produces the braking force by applying a frictional force to a wheel, whereby braking of the vehicle can be achieved.
In general, responsive to a braking command by a driver, a mechanical braking force is applied as a primary braking force and a regenerative braking force is added as an auxiliary braking force. It is important how to balance these mechanical braking force and regenerative braking force.
For example, Japanese Patent Application Laid-Open (Kokai) No. HEI 1-126103 (the first conventional art) discloses a technique in which a command braking force (target braking force) is set from a degree of operation of a brake pedal (which may hereinafter be called a "brake pedal stroke") and an acceleration of the operation of the brake pedal, a regenerative braking force produced at this time in accordance with the degree of operation of the brake pedal is determined, and a mechanical braking force is applied in association with the regenerative braking force to give the command braking force.
As another example, Japanese Patent Application Laid-Open (Kokai) No. HEI 1-198201 (the second conventional art) discloses a technique in which upon operation of brakes, regenerative braking is controlled to make the sum of a mechanical braking force and a regenerative braking force consistent with a target deceleration characteristic.
Further, Japanese Patent Application Laid-Open (Kokai) No. HEI 4-355603 (the third conventional art) discloses a technique in which a ratio of a regenerative braking force to a frictional braking force is computed by a brake controller from a displacement of a brake pedal detected by a displacement detector, a deceleration of a vehicle detected by a deceleration sensor and a vehicle speed detected by a vehicle speed sensor and a regenerative brake and frictional brakes are hence operated efficiently, thereby efficiently recovering regenerative energy and moreover applying a desired braking force to an electric automobile.
According to the above-described first conventional technique, the target braking force and the regenerative braking force are obtained from the degree of operation of the brake pedal and the acceleration of the operation of the brake pedal, and the difference between the target braking force and the regenerative braking force is replenished by the mechanical braking force. No problem would arise if a regenerative braking force is always produced corresponding to a degree of operation of the brake pedal and an acceleration of the operation of the brake pedal. A regenerative brake force is, however, not always produced corresponding to operation of the brake pedal as mentioned above.
Described specifically, for example, when the temperature of a battery is high, charging has to be limited or stopped to protect the battery from deteriorati
REFERENCES:
patent: 4313080 (1982-01-01), Park
patent: 4671577 (1987-06-01), Woods
patent: 4962969 (1990-10-01), Davis
patent: 5322352 (1994-06-01), Ohno et al.
Furukawa Nobuya
Kato Masaaki
Kawamura Nobuyuki
Koga Hisamitsu
Kumagai Naotake
Mitsubishi Jidosha Kogyo Kabushiki Kaisha
Poon Peter M.
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