Tandem master cylinder secondary piston and master cylinder equipped with such a secondary piston

Patent metadata

Field	Value
Publication number	US-9475473-B2
Application number	US-201113996350-A
Country	US
Kind code	B2
Filing date	Dec 5, 2011
Priority date	Dec 21, 2010
Publication date	Oct 25, 2016
Grant date	Oct 25, 2016

Abstract

A master cylinder having a primary piston and a secondary piston is described. The secondary piston is realized of plastic material; it is composed of a skirt and an end wall. The forward edge of the skirt is equipped with longitudinal slots intended to cooperate with the resupply seal to resupply the secondary pressure chamber and ensure operation in rest position whenever the brake circuit is in ESP mode. Supply occurs from the supply chamber, which is connected to the brake fluid reservoir.

First claim

The invention claimed is:

1. A secondary piston of a tandem master cylinder, comprising:
a cylindrical skirt having a free front end and an end wall, the cylindrical skirt being actuatable on a first face of the end wall by a thrust rod of a primary piston and on a second face by a return spring, wherein:
the secondary piston delimits a pressure chamber in the master cylinder,
a forward edge of the secondary piston in a rest position cooperates with a seal housed in a groove in a master cylinder body and separates a supply chamber from the pressure chamber while allowing a hydraulic fluid to pass through passages in the skirt when a brake system is in an ESP mode or is arranged for a resupply, and
an edge of the skirt includes a crenellated profile formed of slots open in front, wherein the radial slots have a straight planar bottom surface that is perpendicular to an axis of the secondary piston.

2. The secondary piston according to claim 1 , wherein the slots are radial and parallel to the axis of the secondary piston.

3. The secondary piston according to claim 2 , wherein the radial slots have sides defined by radially directed planes.

4. The secondary piston according to claim 1 , wherein the slots are helical.

5. The secondary piston according to claim 1 , wherein the secondary piston is made by injection molding a plastic material.

6. A tandem master cylinder, comprising:
a secondary piston that includes:
a cylindrical skirt having a free front end and an end wall, the cylindrical skirt being actuatable on a first face of the end wall by a thrust rod of a primary piston and on a second face by a return spring, wherein:
the secondary piston delimits a pressure chamber in the master cylinder,
a forward edge of the secondary piston in a rest position cooperates with a seal housed in a groove in a master cylinder body and separates a supply chamber from the pressure chamber while allowing a hydraulic fluid to pass through radial slots in the skirt when a brake system is in an ESP mode,
an edge of the skirt includes a crenellated profile formed of the radial slots, wherein the radial slots are open in front and have a straight planar bottom surface that is perpendicular to an axis of the secondary piston, and wherein the secondary piston is made by injection molding with a plastic material.

7. The secondary piston of a tandem master cylinder of claim 1 , wherein the cylindrical skirt further includes a frustoconical housing situated in the end wall, wherein the frustoconical housing accommodates the thrust rod of the primary piston.

8. The tandem mast cylinder of claim 6 , wherein the cylindrical skirt of the secondary piston further includes a frustoconical housing situated in the end wall, wherein the frustoconical housing accommodates the thrust rod of the primary piston.

Assignees

• Charpentier Carole
• Auguste Antony
• Lhuillier Laurent
• Bernadat Olivier
• Rodriguez Marc
• Bosch Gmbh Robert

Inventors

• Charpentier Carole
• Auguste Antony
• Lhuillier Laurent
• Bernadat Olivier
• Rodriguez Marc

Classifications

• B60T11/228

  Pressure-maintaining arrangements, e.g. for replenishing the master cylinder chamber with fluid from a reservoir (B60T11/232 takes precedence) · CPC title

• B60T11/20 Primary

  Tandem, side-by-side, or other multiple master cylinder units · CPC title

• B60T11/232 Primary

  Recuperation valves · CPC title

• B60T11/236

  Piston sealing arrangements · CPC title