The invention refers to a pneumatic brake assistance arrangement (1) with a mechanical combustion-engine-driven vacuum pump (10) and a vacuum brake assistance unit (40), whereby the brake assistance unit (40) comprises a vacuum chamber (42) which is connected with a suction port (17) of the pumping unit (18). The vacuum pump (10) comprises : an input shaft (20) which is directly driven by the combustion engine (12), a pumping unit (18) with a pump rotor (19) and the suction port (17), and a magneto-rheo!ogical clutch (16) being arranged between the input shaft (20) and the pump rotor (19), the clutch (16) comprising an input clutch body (24) and an output clutch body (22), a closed clutch liquid gap (26) between the two clutch bodies (22,24), the clutch liquid gap (26) being filled with a magneto-rheological clutch liquid (28), a shiftable permanent magnet element (30) being shiftable between an engaged position wherein the permanent magnet element's magnetic field penetrates the clutch liquid gap (26) with high magnetic flux and a disengaged position wherein the magnet element's magnetic field penetration flux in the clutch liquid gap (26) is less than in the engaged position, and a pneumatic control circuit for moving the permanent magnet element (30) between its engaged and its disengaged position, the pneumatic control circuit comprising a pneumatic actuation chamber (50) which is connected to the vacuum chamber (42) of the brake assistance unit (40) via a pneumatic conduit (46) and comprising a piston means (52) in the actuation chamber (50), whereby the piston means (52) directly shifts the permanent magnet element (30) into its engaged position when relatively high pressure is present in the vacuum chamber (42), and whereby the piston means (52) is pretensioned by a passive pretension element (44) into the disengaged or engaged position.
Pneumatic brake assistance arrangement
2012-01-01
Abstract
The invention refers to a pneumatic brake assistance arrangement (1) with a mechanical combustion-engine-driven vacuum pump (10) and a vacuum brake assistance unit (40), whereby the brake assistance unit (40) comprises a vacuum chamber (42) which is connected with a suction port (17) of the pumping unit (18). The vacuum pump (10) comprises : an input shaft (20) which is directly driven by the combustion engine (12), a pumping unit (18) with a pump rotor (19) and the suction port (17), and a magneto-rheo!ogical clutch (16) being arranged between the input shaft (20) and the pump rotor (19), the clutch (16) comprising an input clutch body (24) and an output clutch body (22), a closed clutch liquid gap (26) between the two clutch bodies (22,24), the clutch liquid gap (26) being filled with a magneto-rheological clutch liquid (28), a shiftable permanent magnet element (30) being shiftable between an engaged position wherein the permanent magnet element's magnetic field penetrates the clutch liquid gap (26) with high magnetic flux and a disengaged position wherein the magnet element's magnetic field penetration flux in the clutch liquid gap (26) is less than in the engaged position, and a pneumatic control circuit for moving the permanent magnet element (30) between its engaged and its disengaged position, the pneumatic control circuit comprising a pneumatic actuation chamber (50) which is connected to the vacuum chamber (42) of the brake assistance unit (40) via a pneumatic conduit (46) and comprising a piston means (52) in the actuation chamber (50), whereby the piston means (52) directly shifts the permanent magnet element (30) into its engaged position when relatively high pressure is present in the vacuum chamber (42), and whereby the piston means (52) is pretensioned by a passive pretension element (44) into the disengaged or engaged position.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
