# US 2014/0150645 A1 · Plastic primary piston with insert for a tandem penetration-type master cylinder and a master cylinder equipped with such a piston

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- Number: US 2014/0150645 A1
- Document ID: US20140150645A1
- Status: Published application
- Kind: A1
- Application number: 13/996,670
- Filed: 2011-11-30
- Published: 2014-06-05
- Earliest claimed: 2010-12-21
- Assignees: Robert Bosch GmbH
- Inventors: Laurent Lhuillier; Daniel Grech; Olivier Bernadat; Marc Rodriguez
- Web page: https://patentgrep.com/patent/US20140150645A1

## CPC

- F16J 1/01: characterised by the use of particular materials (F16J1/02 takes precedence)
- B60T 11/232: Recuperation valves
- B60T 11/236: Piston sealing arrangements
- F16J: PISTONS {(specially adapted for dampers F16F9/32)}; CYLINDERS; SEALINGS
- B60T: VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL (electrodynamic brake systems for vehicle, in general B60L; brakes per se, i.e. devices where braking effect occurs, including ultimate brake actuators, F16D); ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES

## Abstract

A primary piston of molded plastic material equipped with a metallic insert and having grooves, mounted in a master cylinder comprising at least a primary piston and a secondary piston mounted in the bore hole of the master cylinder. These pistons can create pressure, respectively, in a primary pressure chamber and in a secondary pressure chamber due to the action of a push rod on the primary piston.

## Claims

### Claim at position 1

1-10. (canceled)

### Claim 11

A primary piston for a tandem penetration-type brake master cylinder, comprising:
a primary piston of molded plastic material and having an overmolded stamped sheet-metal insert situated between a forward cavity and a cavity, and also having at least one groove on the surface emerging on a forward face.

### Claim 12 (depends on 11)

The primary piston of claim 11, wherein the primary piston is made of a thermoset plastic material.

### Claim 13 (depends on 11)

The primary piston of claim 11, wherein the metallic insert has at least one hole.

### Claim 14 (depends on 13)

The primary piston of claim 13, wherein the hole is substantially parallel to the axis of the piston.

### Claim 15 (depends on 13)

The primary piston of claim 13, wherein, after injection of the plastic material, the hole of the insert forms a blind hole in the piston.

### Claim 16 (depends on 11)

The primary piston of claim 11, wherein the surface of the piston is ground by machine.

### Claim 17 (depends on 11)

The primary piston of claim 11, wherein the primary piston is made of plastic materials capable of damping noise.

### Claim 18

A master cylinder, comprising:
a master cylinder arrangement; and
at least a primary piston and a secondary piston mounted in a bore hole of the master cylinder arrangement, wherein the primary piston is of molded plastic material and having an overmolded stamped sheet-metal insert situated between the forward cavity and the primary pressure chamber and in that it also has at least one groove on a surface emerging on the forward face.

### Claim 19 (depends on 18)

The master cylinder of claim 18, wherein the primary piston has a metallic insert that has at least one hole.

### Claim 20 (depends on 18)

The master cylinder of claim 18, wherein the insert of the primary piston is made of a magnetizable material, so that the piston emits a magnetic field capable of being detected by a magnetic field sensor.