Brake device for vehicle

A brake device for a vehicle mounted on a vehicle having a plurality of electric brakes, each of which is provided on each wheel, converts torque output by a motor into linear force by a linear motion mechanism and presses the corresponding wheel to generate braking force, the brake device for the vehicle, comprising:

• a braking force control unit including a torque command calculation unit configured to calculate a torque command value for the motor based on a required braking force commanded from an external source, and a current command calculation unit configured to calculate a current command value for energizing the motor based on the torque command value, and that controls the braking force generated by each of the electric brakes;
• wherein
• the electric brake includes a position sensor for detecting an actual position which is an actual rotation angle of the motor or an actual stroke of the linear motion mechanism,
• a relationship between the torque of the motor and the braking force generated by the electric brake has a hysteresis characteristics in which, as the torque increases, the braking force increases along a positive efficiency line, as the torque decreases from a turning value where the torque changes from increasing to decreasing to a holding critical value, the braking force is maintained constant, and as the torque decreases from the holding critical value, the braking force decreases along an inverse efficiency line,
• the torque command calculation unit includes a position controller that calculates the torque command value so that the actual position detected by the position sensor approaches a position command value,
• when an actual braking force, which is the braking force actually output by the electric brake, is increased and maintained at the required braking force,
• a process of increasing the torque of the motor along the positive efficiency line until the actual braking force reaches the required braking force is defined as a first process,
• a process of performing an excess operation of increasing the torque of the motor along the positive efficiency line following the first process until the actual braking force reaches a target excess braking force that is a predetermined excess amount greater than the required braking force is defined as a second process,
• a process of performing a holding operation in which the torque of the motor is reduced while the braking force at an end of the excess operation is held is defined as a third process, and
• a process of performing a return operation to reduce the torque of the motor along the inverse efficiency line until the actual braking force reaches the required braking force is defined as a fourth process, and
• the torque command calculation unit changes the torque command value in an order of the first process to the fourth process and performs a position control by the position controller at least in the second process.