Disc brake caliper with piston roll-back device

Patent metadata

Field	Value
Publication number	US-9285003-B2
Application number	US-201013518397-A
Country	US
Kind code	B2
Filing date	Dec 23, 2010
Priority date	Dec 24, 2009
Publication date	Mar 15, 2016
Grant date	Mar 15, 2016

Abstract

Disc brake calipers with a piston roll-back device capable of allowing accurate and repeatable roll-back of pistons and which are easy to construct and assemble are provided.

First claim

The invention claimed is:

1. A disc brake caliper comprising a caliper body arranged astride a brake disc having a rotational axis defining an axial direction (X-X) and opposite friction surfaces, said caliper comprising pads received in said caliper body so as to be slidable substantially in direction (X-X) axial to the brake disc to respectively operate on said opposite friction surfaces, said caliper body comprising at least one piston seat adapted to receive a piston provided with a lateral surface adapted to slide in said piston seat so as to be forced by pressurized brake fluid exiting from said seat to impact at least one of said pads against one of said friction surfaces of the brake disc, wherein:
 said piston has a substantially cylindrical-shaped piston body having a thrust axis (T-T) substantially parallel to the rotational axis (X-X) of the disc and having a radial direction (R-R) perpendicular to said thrust axis (T-T);
 said piston body having a bottom and a cylindrical wall;
 said piston body having a first annular seat provided in said cylindrical wall;
 said first annular seat being adapted to receive a first gasket;
 said piston body having a second annular seat arranged in said cylindrical wall;
 said second seat being different from said first seat;
 said second annular seat having a shape adapted for a controlled elastic deformation of a second gasket received in said second annular seat;
 said second annular seat being in proximity to an edge nearest the bottom of the piston body comprising a portion that is rounded to define a boundary which defines a volume adapted to receive a gasket portion during elastic deformation thereof determined by the movement of the piston exiting from the piston seat;
said second gasket operating between said piston and said piston seat and being adapted to be deformed elastically in the direction of the thrust axis (T-T) during relative movement of the piston with respect to the piston seat so as to be preloaded elastically to return the piston into the piston seat by a predetermined degree or roll-back upon termination of the braking action,
and wherein:
 said first annular seat is at least partly radially superimposed on said bottom;
 said first annular seat having a substantially square-shaped cross-section with lateral walls transverse to the thrust direction (T-T) and a bottom substantially parallel to said thrust direction (T-T) to receive said first gasket in order not to deform in the thrust direction (T-T) during the relative movement of the piston with respect to the piston seat;
 said second seat receiving said second gasket being arranged on the side opposite from the bottom with respect to said first seat receiving said first gasket, and nearer the pads than said first seat;
 said first gasket operating between said piston and said piston seat so as to provide a fluid sealing capable of allowing pressurization of the fluid, the first sealing gasket keeping the brake fluid away from the second gasket;
 said first gasket comprising:
 a retention ring having a surface, opposite to an annular seat, providing a fluid sealing by acting as a scraper with an inner sliding surface of the piston seat, said retention ring having a radially inner surface facing radially inside the piston and having an annular groove; and
 an underlying gasket partly received in said annular groove of said radially inner surface of the retention ring and prevented by said radially inner surface of the retention ring from deforming in the thrust direction (T-T).

2. The caliper of claim 1 , wherein said piston body comprises an internally hollow portion having dimensions perpendicular to the thrust axis (T-T) wherein the dimensions of the hollow portions increase in proportion to the distance away from said bottom.

3. The caliper of claim 1 , wherein said hollow portion comprises two portions wherein the portion near the bottom has a smaller dimension perpendicular to the thrust axis (T-T) with respect to the second portion.

4. The caliper of claim 1 , wherein said cylindrical wall has a substantially constant radial thickness.

5. The caliper of claim 1 , wherein said cylindrical wall comprises two portions wherein the first portion serves as a spacer between the pad and said annular seats while the second portion is arranged farther from the pad to create a structure adapted to receive the gaskets.

6. The caliper of claim 1 , wherein a first portion of the cylindrical wall comprises lightening means.

7. The caliper of claim 1 , wherein a first portion of the cylindrical wall comprises lightening holes.

8. The caliper of claim 1 , wherein said second annular seat is arranged in a portion of the cylindrical wall superimposed on a second portion of a hollow portion having a smaller diameter with respect to a remaining first portion of the hollow portion.

9. The caliper of claim 1 , wherein said first annular seat comprises two lateral faces arranged perpendicular to the thrust direction (T-T).

10. The caliper of claim 1 , wherein said underlying gasket of the first gasket is an “o-ring” gasket coupled to said retention ring, both of which are received in said first annular seat, and wherein said retention ring comprises opposite lateral walls cooperating with lateral faces of said first annular seat.

11. The caliper of claim 1 , wherein said second gasket comprises a substantially quadrangular-shaped cross-section.

12. The caliper of claim 1 , wherein said second annular seat comprises in proximity to the edge, farthest from the bottom of the piston body, a second portion that is rounded to define a boundary suitable to cause a knock back volume to receive a portion of a gasket during elastic deformation thereof determined by the movement of the piston withdrawing into the piston seat thereof or wherein said second annular seat defines a knock back volume dimensioned to receive a predetermined portion of a gasket so as to obtain a predetermined “knock-back”.

13. The caliper of claim 1 , wherein said bottom of the piston body comprises a bottom seat adapted to receive an elastic element which operates between the piston and the piston seat according to the thrust direction (T-T).

14. The caliper of claim 1 , wherein said bottom comprises a bottom seat configured to enable the correct centering of said elastic element.

15. The caliper of claim 1 , wherein between said bottom and said piston seat a spring is present capable of an elastic constant substantially constant over the entire travel of exit of the piston from the piston seat.

16. The caliper of claim 1 , wherein said second annular seat is spaced from said first annular seat by a distance equal to or less than the width of said first seat with respect to the thrust direction (T-T).

17. The caliper of claim 1 , wherein said second annular seat is spaced from said first annular seat by a distance equal to or less than the width of said second seat with respect to the thrust direction (T-T).

18. The caliper of claim 1 , wherein said second annular seat defines a volume dimensioned to receive a predefined amount of gasket so as to obtain the roll-back of the piston into the piston seat thereof by a predefined desired degree or amount.

19. The caliper of claim 1 , wherein said piston body of said piston is a single piece.

20. The caliper of claim 1 , wherein said second annular seat receives a gasket operating between said piston and said piston seat and adapted to be deformed elastically in the direction of the thrust axis

Assignees

• Cornolti Raffaello
• Previtali Alberto
• Gelfi Luca
• Freni Brembo Spa

Inventors

• Cornolti Raffaello
• Previtali Alberto
• Gelfi Luca

Classifications

• F16D2127/02

  Release mechanisms · CPC title

• F16D2125/06

  Pistons · CPC title

• F16D65/14 Primary

  Actuating mechanisms for brakes; Means for initiating operation at a predetermined position (brake control systems, parts thereof B60T) · CPC title