Method for controlling a hydraulic brake system during a regenerative braking process, hydraulic brake system, computer program product, control unit and motor vehicle

A hydraulic brake system for a motor vehicle, comprising:

• a brake cylinder and a wheel brake which are hydraulically connected to one another via a feed line, wherein the brake cylinder is configured to displace a hydraulic fluid in the direction of the wheel brake, and the wheel brake is configured to impart a hydraulic braking torque by means of the hydraulic fluid;
• an isolation valve which is fluidically assigned to the feed line and which is configured to close the feed line;
• a return line for returning at least a volume fraction of the hydraulic fluid from a region positioned downstream of the isolation valve into a region positioned upstream of the isolation valve;
• a pressure dissipation valve, a pump and an accumulator, which are fluidically assigned to the return line, wherein the pump is configured to convey at least a volume fraction of the hydraulic fluid, the accumulator is configured to store at least a volume fraction of the hydraulic fluid, and the pressure dissipation valve is configured to open the return line;
• a control unit which is connected in signal-exchanging fashion to the isolation valve, the pressure dissipation valve and the pump and which is configured such that, in the presence of an actuation of the brake cylinder and in particular in the presence of a generator braking torque of an electric machine, the control unit activates the isolation valve for adjustment in the direction of a closed state in order to set a pressure difference between the region positioned upstream and the region positioned downstream.