Valve assembly and method for regulating the pressure of a fluid

A valve assembly for controlling a pressure of a fluid, comprising:

• an actuator;
• a proportional valve operably connected to the actuator, the proportional valve having an opening cross section that can be continuously varied by the actuator;
• a sensor operably connected to the proportional valve and configured to sense a valve output pressure of the proportional valve;
• a digital controlling device;
• and
• a switching valve arranged parallel to the proportional valve and having an opening cross section,
• wherein the opening cross section of the switching valve is smaller than a maximum opening cross section of the proportional valve,
• wherein, during a running time, the digital controlling device is configured to automatically calculate a working pressure achievable as a maximum with the proportional valve when the proportional valve is configured at the maximum opening cross section based on a currently given valve output pressure from the sensor and a current position of the actuator, and
• wherein the digital controlling device is further configured to open the switching valve when the calculated maximum achievable working pressure falls below a predefinable target working pressure by a determinable deviation value.