Hydraulic dual circuit brake system for road vehicles

US4629258A · kind A · utility

Assignee

• Daimler-Benz AG · DE

Inventors

• Reinhard Resch · Stuttgart, DE
• Hellmut Krohn · Eßlingen, DE

Key dates

• Filing date: Dec 26, 1984
• Grant date: Dec 16, 1986
• Expiry date: Dec 26, 2004

Classification

• Technology area (CPC B): Performing Operations; Transporting
• CPC primary: B60T17/225
• WIPO field: Transport
• WIPO sector: Mechanical engineering

Abstract

A hydraulically power-assisted dual circuit brake system for road vehicles combined with an anti-locking brake system has a stepped tandem master cylinder and a primary piston. The primary piston includes a ring piston which is displaceable in a larger cylinder step and a plunger which is displaceable in said ring piston. A pre-pressure acting on the control area of the plunger of the primary piston is built up by pedal actuation of a further plunger. This pre-pressure operates as a reference pressure and is also coupled into a proportional control valve. The proportional control valve provides a control output pressure which is taken from the auxiliary pressure source and is higher. The control output pressure is used to impinge the ring piston and thereby move the plunger of the primary piston. With use of the ABS control, at least a secondary brake circuit, in a special design a primary brake circuit as well, is switched over from static to dynamic operation. In dynamic operation, the output pressure of the proportional control valve is used to operate the selected brake circuit. A stroke sensor monitoring the displacement stroke of the ring piston generates an output signal ind…