| 主权项 |
1. A vehicle brake device comprising:
a friction-applying member; a friction-applied member that is attached to a wheel; an electric parking brake that generates a braking force by electric power using the friction-applying member and the friction-applied member; a service brake that generates a braking force by brake fluid pressure using the friction-applying member and the friction-applied member; and electronic control means for controlling operations of the electric parking brake and the service brake, wherein the service brake includes brake fluid pressure generation means for generating a brake fluid pressure, and a wheel cylinder which is connected to the brake fluid pressure generation means, and which generates a braking force by a piston being pressed by an increase in the brake fluid pressure and causing the friction-applying member to come into contact with and press against the friction-applied member, and which moves the friction-applying member together with the piston in a direction in which the friction-applying member is separated from the friction-applied member by a decrease in the brake fluid pressure, the electric parking brake moves the friction-applying member together with the piston based on a torque of an electric motor, moves the piston by driving the electric motor to rotate in a forward direction, and thereby causes the friction-applying member to come into contact with and press against the friction-applied member, thus generating a parking brake force, the electric parking brake is also configured to move the piston by driving the electric motor to rotate in a reverse direction, and to thereby cause the friction-applying member to be separated from the friction-applied member, thus releasing the parking brake force, the electronic control means includes release control means for performing release control that releases the parking brake force by driving the electric motor to rotate in the reverse direction and causing the electric parking brake to perform a release operation, and the release control means includes release impossible determination means for determining a release impossible state in which the release operation cannot be performed, based on a fact that a motor current that is supplied to the electric motor in the release control is maintained in a state of a locked rotor current, pressurization means that performs, when the release impossible state is determined, back-up pressurization for pressing the piston by generating a brake fluid pressure in the wheel cylinder using the service brake and for pressing the friction-applying member against the friction-applied member, and release means for causing the electric parking brake to perform the release operation and releasing the parking brake force by driving the electric motor to rotate in the reverse direction when the back-up pressurization is being performed. |
