Development of Electronically Controlled Brake System for Hybrid Vehicle 2002-01-0300

We expect to reduce exhaust gas emissions further and improve fuel consumption, by developing a new brake system (called brake-by-wire system) to control the friction brake force and the regenerative brake force of the two motors, one each at front and rear axle. Within this new system we developed the new technology listed below.

1. 1
   To compensate the changes of the regenerative brake force of front and rear motors, the friction brake force is controlled by adjusting the wheel cylinder hydraulic pressures.
2. 2
   The pressure of each wheel cylinder is controlled by linear solenoid valves. So the hydraulic pressure of wheel cylinders is controlled individually and smoothly.

This brake system also operates ABS, VSC, TRC functions. The vehicle stability performance is improved by controlling the braking and driving torque of two motors and also controlling the friction brake torque cooperatively. By using this new brake system, it is possible to make maximum use of the regenerative brake, which reduces exhaust gas and improves fuel consumption with the same brake pedal operation as in conventional vehicles. This brake system, that is able to control the hydraulic pressure of four wheel cylinders individually and smoothly, has high potential to add functional enhancements with proper modifications of software. So that this brake system is expected to become the core technology for further improvement of the vehicle stability and convenience.