# US 2008/0189019 A1 · Method for Operating a Hydraulic Braking System for Motor Vehicles > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2008/0189019 A1 - Document ID: US20080189019A1 - Status: Published application - Kind: A1 - Application number: 11/793,632 - Filed: 2005-12-21 - Published: 2008-08-07 - Earliest claimed: 2004-12-21 - Assignees: Continental Teves AG & Co. oHG - Inventors: Samir Attayebi; Marcus Bletz; Oliver Huth; Mohieddine Challouf - Web page: https://patentgrep.com/patent/US20080189019A1 ## CPC - B60T 7/107: {with electrical power assistance} - B60T 8/32: responsive to a speed condition, e.g. acceleration or deceleration ({using electrical circuitry or regulation means B60T8/17} ; B60T8/28 takes precedence; electric devices on electrically propelled vehicles indicating the wheel slip B60L3/10; measuring linear or angular speed per se G01P3/00) - B60T 8/4872: {pump-back systems} - B60T 13/741: {acting on an ultimate actuator} - F16D 65/14: Actuating mechanisms for brakes; Means for initiating operation at a predetermined position (brake control systems, parts thereof B60T) - F16D 65/18: adapted for drawing members together {, e.g. for disc brakes} - F16D 2121/02: Fluid pressure - F16D 2121/12: for releasing a normally applied brake, the type of actuator being irrelevant or not provided for in groups F16D2121/04 - F16D2121/10 - F16D 2121/14: Mechanical - F16D 2123/00: Multiple operation forces - F16D 2125/40: Screw-and-nut - F16D 2127/06: Locking mechanisms, e.g. acting on actuators, on release mechanisms or on force transmission mechanisms - F16D 2129/08: Electromagnets - 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 - F16D: COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES ## Abstract The invention relates to a method for operating a hydraulic braking system for motor vehicles, comprising a service brake system and a parking brake device, with the service :Drake system including a pedal-operable hydraulic pressure generator, to which two brake circuits with at least one externally controllable hydraulic pressure source are connected, and a hydraulically operable front-axle wheel brake provided with inlet and outlet valves and a hydraulically operable rear-axle wheel brake provided with inlet and outlet valves are associated with each one brake circuit, and with the parking brake device including means for arresting the brake pistons of the rear-axle wheel brakes, the brake pistons being acted upon by hydraulic pressure supplied by the pressure source for the purpose of activation or deactivation of the parking brake device. In order to render the working time of the externally controllable hydraulic pressure source shorter during deactivation of the parking brake device, according to the invention, the hydraulic pressure is used at least partly to apply the front axle wheel brakes after deactivation of the parking brake device. ## Claims ### Claim 1 Method for operating a hydraulic braking system for motor vehicles, comprising a service brake system and a parking brake device, with the service brake system including a pedal-operable hydraulic pressure generator (10), to which two brake circuits (I, II) with at least one externally controllable hydraulic pressure source (4, 40) are connected, and a hydraulically operable front-axle wheel brake (2) provided with inlet and outlet valves (13, 14) and a hydraulically operable rear-axle wheel brake (3) provided with inlet and outlet valves (17, 18) are associated with each one brake circuit (I, II), and with the parking brake device including means for arresting the brake pistons of the rear-axle wheel brakes (3), the brake pistons being acted upon by hydraulic pressure supplied by the pressure source (4, 40) for the purpose of activation or deactivation of the parking brake device, characterized in that the hydraulic pressure, after deactivation of the parking brace device, is used at least partly for the operation of the front-axle wheel brakes (2). ### Claim 2 (depends on 1) Method as claimed in claim 1, characterized in that the following process steps are performed: closing the inlet valves (13) associated with the front-axle wheel brakes (2); buildup of hydraulic pressure by the hydraulic pressure source (4, 40) in the rear-axle wheel brakes (3); deactivating the parking brake device and terminating the hydraulic pressure buildup; opening the inlet valves (13) associated with the front-axle wheel brakes (2). ### Claim 3 (depends on 2) Method as claimed in claim 2, characterized in that additional pressure buildup is carried out by the hydraulic pressure source (4, 40) after the inlet valves (13) associated with the front-axle wheel brakes (2) have been opened. ### Claim 4 Method as claimed in any one of the preceding claims, characterized in that hydraulic pressure introduced into the front-axle wheel brakes (2) is used at least partly for the activation of the parking Drake device on the rear-axle wheel brakes (3). ### Claim 5 (depends on 4) Method as claimed in claim 4, characterized in that the following process steps are performed: buildup of hydraulic pressure by the hydraulic pressure source (4, 40) or by the operator in the front-axle and rear-axle wheel brakes (2, 3); closing the inlet valves (13) associated with the front-axle wheel brakes (29) and opening the outlet valves (14) associated with the front-axle wheel brakes (2); displacing the pressure fluid volume introduced into the front-axle wheel brakes (2) into a low-pressure accumulator (15, 16); buildup of additional hydraulic pressure by the hydraulic pressure source (4, 40) in the rear-axle wheel brakes (3); activating the parking brake device and terminating the hydraulic pressure buildup; opening the outlet valves (18) associated with the rear-axle wheel brakes (2).