Patent ID: 6715846
Filing Date: 2004-04-06
Classification: B60T

Abstract:
A braking pressure control device for a vehicle, comprising:a pneumatic brake booster, which includes at least two chambers, which are separable from each other, and from which at least one is operable as a low-pressure chamber and at least one other is operable as a working chamber; a main cylinder, in which a main-cylinder pressure is generatable by the pneumatic brake booster in accordance with a specifiable control pressure; a hydraulic unit, which is inserted between the main cylinder and at least one wheel-brake cylinder of at least one wheel, the hydraulic unit including an array of switchable valves and at least one pump; wherein: a wheel-brake cylinder pressure higher than the main-cylinder pressure is generatable in the at least one wheel-brake cylinder with the hydraulic unit, the pneumatic brake booster has a first control point, and a first ratio of the main-cylinder pressure to the control pressure is predefined up to the first control point; wherein in the pneumatic brake booster: a second ratio of the main-cylinder pressure to the control pressure is preselected, a greater pneumatic brake boost of the main-cylinder pressure by the control pressure is achievable with the second ratio than would otherwise be achievable with the first ratio, the maximum achievable brake boost of the pneumatic brake booster, using the second ratio, is attained at a second control point, the second control point is attained at a main-cylinder pressure of greater than 0 and less than 50 bar, and a generation of an increased wheel-brake cylinder pressure, using a hydraulic brake boost by the hydraulic unit, sets in at the second control point.