PNEUMATIC BRAKE ASSISTANCE ARRANGEMENT

摘要

A pneumatic brake assistance arrangement includes a vacuum brake assistance unit comprising a vacuum chamber, and a vacuum pump. The vacuum pump comprises an input shaft, a pumping unit, and a magneto-rheological clutch. The pumping unit comprises a pump rotor and a suction port connected to the vacuum chamber. The magneto-rheological clutch comprises an input clutch body, an output clutch body, a closed clutch liquid gap, a permanent magnet element, and a pneumatic control circuit. The permanent magnet element shifts between an engaged and a disengaged position. The pneumatic control circuit moves the permanent magnet element between the engaged and the disengaged position. The pneumatic control circuit comprises a pneumatic actuation chamber comprising a piston and a passive pretension element. The pneumatic actuation chamber is connected to the vacuum chamber. The piston shifts the permanent magnet element into the engaged position when a high pressure exists in the vacuum chamber.