Pneumatic brake assistance arrangement

A pneumatic brake assistance arrangement for an internal combustion engine, the pneumatic brake assistance arrangement comprising:

• a pneumatic conduit;
• a vacuum brake assistance unit comprising a vacuum chamber;
• and
• a vacuum pump comprising,
• an input shaft configured to be directly driven by the internal combustion engine,
• a pumping unit comprising a pump rotor and a suction port, the vacuum chamber of the vacuum brake assistance unit being connected with the suction port of the pumping unit, and
• a magneto-rheological clutch arranged between the input shaft and the pump rotor, the magneto-rheological clutch comprising,
• an input clutch body,
• an output clutch body,
• a closed clutch liquid gap arranged between the input clutch body and the output clutch body, the closed clutch liquid gap being filled with a magneto-rheological clutch liquid,
• a permanent magnet element configured to be shiftable between an engaged position wherein a magnetic field of the permanent magnet element penetrates the closed clutch liquid gap with a high magnetic flux, and a disengaged position wherein the magnetic field of the permanent magnet element is less than in the engaged position, and
• a pneumatic control circuit configured to move the permanent magnet element between the engaged position and the disengaged position, the pneumatic control circuit comprising a pneumatic actuation chamber comprising a piston and a passive pretension element,
• wherein,
• the pneumatic actuation chamber is connected to the vacuum chamber of the vacuum brake assistance unit via the pneumatic conduit,
• the piston is configured to directly shift the permanent magnet element into the engaged position when a high pressure exists in the vacuum chamber, and
• the passive pretension element is configured to pretention the piston so that the permanent magnet element is in the disengaged position or in the engaged position.