US 5,927,829 AGranted

Brake apparatus for electric automobile utilizing regenerative braking

AssigneeMitsubishi Jidosha Kogyo Kabushiki Kaisha

InventorsKenichi Saga, Hiroaki Yoshida, Akira Maeda

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Abstract

A brake apparatus for an electric automobile applies brakes to the vehicle to achieve a required amount of braking force by combining regenerative braking force of an electric motor with mechanical braking force produced by a mechanical braking system. The braking force required by a driver is obtained from the depression force applied to a brake pedal, and the maximum regenerative braking force, that can be generated by the motor, is obtained from the rotation speed of the motor. The target mechanical braking force is calculated based on the required braking force and the maximum regenerative braking force. By suitably controlling the pneumatic pressure applied to a booster device provided in the mechanical brake system, the fluid pressure actually applied to brake actuating members is controlled to provide the target mechanical braking force.

Claims13

Dependent claims

A brake apparatus utilizing regenerative braking and mechanical braking, for use in an electric automobile having an electric motor driven by a battery installed in the automobile, comprising:

a mechanical brake system which includes a master cylinder for converting depression force applied to a brake pedal provided in said electric automobile into a first fluid pressure, through a booster device for amplifying said depression force by a second fluid pressure, and a brake actuating member for receiving said first fluid pressure generated by said master cylinder and applying a mechanical braking force to a vehicle wheel;
a regenerative braking force calculating unit which calculates a maximum regenerative braking force based on a detected rotation speed of said electric motor;
a regenerative brake system which generates a regenerative braking force in said electric motor, based on a result of calculation of said regenerative braking force calculating unit;
a brake pedal operation detecting unit which detects an operated state of said brake pedal;
a required braking force calculating unit which calculates a required braking force required by a driver based on said detected operated state of said brake pedal;
a target mechanical braking force calculating unit which calculates a target mechanical braking force to be generated by said mechanical brake system based on said required braking force calculated by said required braking force calculating unit and said maximum regenerative braking force calculated by said regenerative braking force calculating unit so that the target mechanical braking force is derived from the detected rotation speed of said electric motor;
and
a mechanical braking force control unit which controls the second fluid pressure applied to said booster device so that the fluid pressure generated by said master cylinder provides the target mechanical braking force calculated by said target mechanical braking force calculating unit.

5 more elements

A brake apparatus utilizing regenerative braking and mechanical braking, for use in an electric automobile having an electric motor driven by a battery installed in the automobile, comprising:

a mechanical brake system which includes a master cylinder for converting depression force applied to a brake pedal provided in said electric automobile into a fluid pressure, and a brake actuating member for receiving said fluid pressure generated by said master cylinder and applying a mechanical braking force to a vehicle wheel of the automobile;
a regenerative braking force calculating unit which calculates a maximum regenerative braking force based on a rotation speed of said electric motor;
a regenerative brake system which generates a regenerative braking force in said electric motor based on a result of calculation of said regenerative braking force calculating unit;
a brake pedal operation detecting unit which detects an operated state of said brake pedal;
a required braking force calculating unit which calculates a required braking force required by a driver based on said operated state of said brake pedal detected by said brake pedal operation detecting unit;
a target mechanical braking force calculating unit which calculates a target mechanical braking force to be generated by said mechanical brake system based on said required braking force calculated by said required braking force calculating unit and a compensated value of said maximum regenerative braking force, said compensated value being obtained by compensating the maximum regenerative braking force calculated by said regenerative braking force calculating unit based on a predetermined variation limiting threshold value when a variation per unit time of a value that corresponds to the maximum regenerative braking force exceeds said predetermined variation limiting threshold value, said maximum regenerative braking force being outputted as it is as said compensated value when the maximum regenerative braking force is not greater than said predetermined variation limiting threshold value;
and
a mechanical braking force control unit which controls said mechanical brake system such that the fluid pressure generated by said master cylinder provides the target mechanical braking force calculated by said mechanical braking force calculating unit.

5 more elements

Dependencies are inferred from the claim text.