# US 2015/0145321 A1 · Vehicle brake device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2015/0145321 A1 - Document ID: US20150145321A1 - Status: Published application - Kind: A1 - Application number: 14/402,137 - Filed: 2013-05-28 - Published: 2015-05-28 - Earliest claimed: 2012-05-28 - Assignees: Advics Co., Ltd. - Applicants: Advics Co., Ltd. - Inventors: Kentaro Yuasa; Masatoshi Hanzawa - Web page: https://patentgrep.com/patent/US20150145321A1 ## CPC - B60T 8/17: Using electrical or electronic regulation means to control braking {(detecting or indicating faulty operation B60T8/885)} - B60T 8/172: Determining control parameters used in the regulation, e.g. by calculations involving measured or detected parameters {(B60T8/17551 takes precedence)} - B60T 13/662: {characterised by specified functions of the control system components} - B60T 13/741: {acting on an ultimate actuator} - B60T 17/221: {Procedure or apparatus for checking or keeping in a correct functioning condition of brake systems (hydraulic pressure systems in general F15B19/00, F15B21/04; testing structures or apparatus G01M)} - B60T 2270/402: Back-up - B60T: VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL (electrodynamic brake systems for vehicle, in general B60L; brakes per se, i.e. devices where braking effect occurs, including ultimate brake actuators, F16D); ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES ## Abstract An electronic control device for controlling operations of an electric parking brake and a service brake: determines a release impossible state in which release operation cannot be performed, based on a fact that a motor current that is supplied to an electric motor of the electric parking brake during release control is maintained in a state of a locked rotor current; and 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. ## Claims ### Claim 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. ### Claim 2 (depends on 1) The vehicle brake device according to claim 1, wherein the service brake includes brake fluid pressure adjustment means that has an automatic pressurization function that automatically increases the brake fluid pressure in the wheel cylinder, and the pressurization means performs the back-up pressurization based on the automatic pressurization function of the brake fluid pressure adjustment means provided in the service brake. ### Claim 3 (depends on 1) The vehicle brake device according to claim 1, wherein the pressurization means uses a notification device to perform notification of the release impossible state when the release impossible state is determined by the release impossible determination means, and thus causes a driver to operate the service brake and to perform the back-up pressurization. ### Claim 4 (depends on 1) The vehicle brake device according to claim 1, wherein the release control means includes drive stop means for stopping the supply of the motor current to the electric motor when the release impossible state is determined by the release impossible determination means, and re-drive means for once more performing the supply of the motor current to the electric motor that has been stopped by the drive stop means, when the back-up pressurization is performed, and for driving the electric motor to rotate in the reverse direction. ### Claim 5 (depends on 1) The vehicle brake device according to claim 1, wherein the electronic control means includes lock control means for performing lock control that generates the parking brake force by driving the electric motor to rotate in the forward direction and causing the electric parking brake to perform a lock operation, and the pressurization means generates, as the back-up pressurization, at least a brake fluid pressure that corresponds to a difference between a motor current value at the end of previous lock control performed before the release control and a value of the locked rotor current.