Robert Boschgmbh

Marc Noblet

Olivier Bernadat

Marc Rodriguez

Julien Gateau

Laurent Lhuillier

Serge Aquino

Daniel Grech

Philippe Bourlon

Chris Anderson

Antony Auguste

Stéphane Lacroix

Carole Charpentier

Yannick Nen

Omar Brahmi

Nicolas Quiniou

Lionel Bourgois

François Gaget

Omar Brahml

Dominique Rault

Lionel Bourgols

Jérémy Labarre

Hervé Pujol

Thierry Fausten

A primary piston composed of a skirt and an intermediate back wall having a rear face receiving the servobrake thrust rod and a forward face for the telescoping rod and the spring pushing the secondary piston. The front of the skirt has longitudinal grooves open in front and closed in the rear. The thickness of the skirt beneath the grooves and the part of the skirt between two successive grooves in the peripheral direction form a front face enabling the principal piston to push the secondary piston. The principal piston is made of a single piece of plastic material.

Primary piston for a tandem master cylinder and tandem master cylinder equipped with such a primary piston

A master-cylinder seal housed in a groove around a piston has a core connected to three annular and concentric lips. The core rests against a side of the groove and has: a surface provided with an interior edge followed by a peripheral platter cut by at least one channel, and an exterior crown provided with a connection zone formed by an interruption in the crown and deformable due to pressure within the seal to recreate the crown's continuity and impermeability while facilitating purging the brake system when there is no pressure in the channel and the connection zone.

Brake system master-cylinder seal

Master-cylinder seal housed in a groove around a piston has a core connected to three annular and concentric lips. The core rests against a side of the groove and has: a surface provided with an interior edge followed by a peripheral platter cut by at least one channel, and an exterior crown provided with a connection zone formed by an interruption in the crown and deformable due to pressure within the seal to recreate the crown's continuity and impermeability while facilitating purging the brake system when there is no pressure in the channel and the connection zone.

A cup for a master cylinder coming into contact with its primary piston or its secondary piston and subjected to the pressure of the brake fluid of the primary chamber and of the secondary chamber. The cup has two large grooves bordered: by a rib between the heel and the first groove, by a rib between the first groove and the second groove, by a rib between the second groove and the small grooves, these ribs being in protrusion relative to the cylindrical surface of the heel in the mounted position of the cup in order to separate the heel from the surface of the piston and form, between the heel and the surface of the piston, a gap with a film of brake fluid. Master cylinder notably a tandem master cylinder fitted with such cups.

Cup of a master cylinder, advantageously a tandem master cylinder and tandem master cylinder provided with such cups

The invention relates to a motor vehicle master cylinder (). More specifically, the invention relates to a piston () of the master cylinder which has a first indentation () and a second indentation (), which indentations are formed upstream of a port () of the piston. The first indentation and the second indentation delimit a space within which hydraulic brake fluid can be stored so that it can be tapped off by an auxiliary braking device of the E.S.P. type.

Vehicle master cylinder connected to an auxiliary braking device

Our problem relates to a master cylinder with a U-shaped seal. Our goal is to avoid defective bleeding of hydraulic braking systems. The defects arise out of the fact that the vacuum causes the lips of the seal () to stick together and to stick against the wall (). To achieve this, reliefs () will be created on one wall () of one lip () facing the other lip () and on the edge face () of this same lip. These reliefs will prevent the lips from sticking tightly to one another and to the wall facing the edge face of the lips. This lack of sticking will prevent a vacuum from being created between the two lips and between the edge face of the lips and the wall (). As a result, the seal will be able to return to a position in which bleeding can be performed effectively.

Master cylinder with U-shaped seal

A master cylinder with increased safety having a piston produced by molding a plastic or aluminum alloy. The piston slides in a bore blocked off by an end wall. A valve for the master cylinder bears at rest against a pin that is fixedly mounted in the body of the master cylinder passes through the piston via a longitudinal slot. The dimensions of the master cylinder are determined such that the piston bears against the pin before coming into contact with the end wall of the master cylinder body.

Master cylinder with increased safety and piston for such a master cylinder

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Paris, France

Marc Noblet