Method for operating a brake system for motor vehicles, and brake system

A brake system for motor vehicles, comprising

• a master brake cylinder which can be actuated by a brake pedal and which is separably connected to at least one brake circuit (I, II) with at least one hydraulically actuable wheel brake,
• a measuring device for determining a first variable (PTHZ) which characterizes a pressure in the master brake cylinder, and a measuring device for determining a second variable (SPedal) which characterizes an actuation travel of the brake pedal,
• a hydraulically actuable pedal travel simulator which is or can be connected to the master brake cylinder and which is designed so as to be capable of being switched on and off by means of a simulator release valve,
• an electrically controllable pressure supply device which is separably connected to the brake circuit (I, II) and which is formed by a cylinder-piston arrangement whose piston can be actuated by an electromechanical actuator,
• a wheel brake pressure modulation unit which has, per wheel brake, an inlet valve and an outlet valve for setting a wheel-specific brake pressure which is derived from the pressure in the brake circuit (I, II), and
• an electronic open-loop and closed-loop control unit for activating the electrically controllable pressure supply device and valves of the brake system,
• wherein in a first operating mode (ZA) when the brake pedal is actuated a pressure (PSetp) of the pressure supply device is applied to the brake circuit (I, II), and wherein in a second operating mode (ZP) when the brake pedal is actuated the pressure (PTHZ) of the master brake cylinder is applied to the brake circuit (I, II),
• wherein
• in the case of a changeover from the second operating mode (ZP) into the first operating mode (ZA) during actuation of the brake pedal the open-loop and closed-loop control unit carries out adjustment of the actuation travel (SPedal) of the brake pedal.