Throttle grooves and control loop/method to achieve an optimized pressure constant backflush procedure of the screen cavity of a screen changer during backflush

A filtering device for filtering a fluid, in particular a liquefied plastic, comprising:

• a housing having a receptacle for receiving a screen carrier, and having a fluid inlet channel and a fluid outlet channel;
• and
• a screen carrier movably received along a longitudinal axis inside the receptacle and having a screen carrier inlet, a screen carrier outlet and a cavity for receiving a filter element, wherein the cavity is in fluid communication with the screen carrier inlet and the screen carrier outlet,
• wherein the screen carrier can be moved from a screen replacement position via a venting position area into a filtering position, and
• wherein the screen carrier has a throttle recess which is arranged adjacent to the screen carrier outlet and which is in fluid communication with the cavity, and which opens a variable flow cross-section between the cavity and the fluid outlet channel, depending on a position of the throttle recess relative to the fluid outlet channel.