BRAKE CONTROL SYSTEM


  1. OUTLINE


    1. The brake actuator and the skid control ECU have been integrated and a hydraulic brake booster has been provided, thus optimizing the hydraulic circuit and offering a weight reduction.

    2. The brake control functions (ABS with EBD, Brake Assist, TRC and VSC+) are provided.

    3. The VSC+ that performs cooperative control with the EPS is used.

    4. An electronically controlled brake system is used at each of the 4 wheels.

    5. Regenerative brake cooperative control is used.

    6. A TRC OFF switch is used.

  2. MAJOR DIFFERENCE


    1. The new models have been modified from the previous models as shown below:


      1. A TRC OFF switch has been added.

      2. A combination meter assembly with the color type multi-information display has been added.

      3. The slip indicator lights up by ABS operation has been added.

  3. MAIN FEATURES


    1. Electronically Controlled Brake System


      1. In this system, the conventional brake booster portion has been discontinued. Instead, it consists of a hydraulic brake booster, brake actuator and brake booster pump assembly.

      2. During normal braking, the fluid pressure generated by the hydraulic brake booster does not directly actuate the wheel cylinders, but serves as a hydraulic pressure signal. Instead, the actual control pressure is obtained by regulating the fluid pressure of the brake booster pump assembly, which actuates the wheel cylinders.

      3. When the skid control ECU detects a fault in the system, brake force can be ensured by applying the brake using the fluid pressure boosted by the hydraulic brake booster.

        B0022MRE03

    2. Regenerative Brake Cooperative Control


      1. Regenerative braking consists of a resistance force that is generated at the rotational axle in the reverse direction of the rotation of the generator (MG2) that is generating electricity. The greater the generated amperage (battery charging amperage), the greater the resistance force will be.

        B0022S6E06
        Text in Illustration
        *1 MG1 *1 Inverter
        *3 Engine *4 MG2
        *a Rotating direction to electricity generation *b Resistance
        *c Brake Force - -

      2. The drive wheels and MG2 are joined mechanically. When the drive wheels rotate MG2 and cause it to operate as a generator, the regenerative brake force of MG2 is transmitted to the drive wheels. Based on the signals from the skid control ECU, this force is controlled by the hybrid system, which controls the generation of electricity.

      3. The regenerative brake cooperative control does not rely solely on the braking force of the hydraulic brake system to supply the brake force required by the driver. Instead, by effecting cooperative control with the hybrid system, this control provides a joint braking force provided by regenerative braking and the hydraulic braking. As a result, this control minimizes the loss of kinetic energy associated with the normal hydraulic braking, and recovers this energy by converting it into electrical energy.

      4. The apportioning of brake force between hydraulic braking and the regenerative braking varies according to vehicle speed and time.

      5. The apportioning of brake force between hydraulic braking and the regenerative braking is accomplished by controlling hydraulic braking so that the total brake force of the hydraulic braking and the regenerative braking matches the brake force required by the driver.

      6. If the regenerative braking becomes inoperative due to a malfunction in the hybrid system, the brake system effects control so that the entire brake force required by the driver is supplied by the hydraulic brake system.

        B0022D1E27

    3. SPORT Mode


      1. In SPORT mode, TRC, power steering control and hybrid transaxle control are adjusted to be suitable for sporty driving, providing sporty acceleration and stable and direct handling performance.

      2. SPORT mode can be entered using the Drive Mode Select.

        B0022AUE02
        Text in Illustration
        *a SPORT Mode On *b SPORT Mode Off

    4. VSC+


      1. In the past, the brake control functions (ABS, TRC, VSC) and the EPS (Electronic Power Steering) were controlled individually. In contrast, the new model uses the VSC+, which uses a cooperative control with EPS. This system effects brake control functions and the EPS in accordance with driving conditions. Thus, it realizes the dynamic performance of the vehicle to "run, turn and stop" and ensures excellent driving stability and drivability.

        B0022JRE21

  4. PRECAUTION


    1. When the brake control system is activated, the brake pedal shudder, which is a normal occurrence of the system in operation and should not be considered as malfunction.