PISTON WITH IMPROVED DISPLACEMENT PROPERTIES

• US 20110308904A1
• Filed: 06/21/2010
• Published: 12/22/2011
• Est. Priority Date: 06/21/2010
• Status: Active Grant

• Current Assignee: Akebono Corporation North America (Akebono Brake Corporation)
• Original Assignee: Akebono Corporation North America (Akebono Brake Corporation)
• Inventors: Alamin, Amar, Roszman, Eric
• Granted Patent: US 8,348,030 B2
• Time in Patent Office: Days
• US Class Current: 188/370
• CPC Class Codes: B60T 1/08 using fluid or powdered medium
• CPC Class Codes: F16D 2125/06 Pistons
• CPC Class Codes: F16D 2200/0004 metallic
• CPC Class Codes: F16D 2200/0034 non-metallic
• CPC Class Codes: F16J 1/001 One-piece pistons

Abstract

A brake pad actuating device comprising: a piston including: a first pocket; an opposing second pocket; and an internal wall located in the piston separating the first pocket and the second pocket, wherein the volume of the first pocket to the volume of the second pocket form a ratio of less than about 20:1; and wherein the piston is adapted to be used as a brake piston.

Claims

1. ) A brake pad actuating device comprising:

a) a piston including;

i) a first pocket;

ii) an opposing second pocket; and

iii) an internal wall located in the piston separating the first pocket and the second pocket,

wherein the volume of the first pocket to the volume of the second pocket form a ratio of about 20;

1 or less; and

wherein the piston is adapted to be used as a brake piston.

2. ) The brake pad actuating device of claim 1, wherein the volume of the first pocket to the volume of the second pocket form a ratio about 10:

1 or less.

3. ) The brake pad actuating device of claim 1, wherein the volume of the first pocket to the volume of the second pocket form a ratio of between about 5:

1 to about 1;

1.

4. ) The brake pad actuating device of claim 1, wherein the volume of the first pocket to the volume of the second pocket form a ratio of between about 2:

1 to about 1;

2.

5. ) The brake pad actuating device of claim 1, wherein the piston is made of a moldable plastic material that does not dissolve in brake fluid.

6. ) The brake pad actuating device of claim 1, wherein the piston is sufficiently rigid to withstand fluid pressure that pushes the piston into contact with an inboard brake pad.

7. ) The brake pad actuating device of claim 1, wherein fluid fills the second pocket and surrounds a sliding surface of the second pocket so that pressure is only exerted axially in relationship to the piston.

8. ) The brake pad actuating device of claim 1, wherein substantially equal amounts of force, in the radial direction, are exerted on the inside of the second pocket wall and the outside of the second pocket wall.

9. ) The brake pad actuating device of claim 1, wherein pressure is exerted on the piston, and substantially all of the pressure is exerted axially on the internal wall.

10. ) The brake pad actuating device of claim 1, wherein the internal wall of the piston is located in proximity to a seal groove when the brake pads are fully worn, and the piston is in a fully extended position.

11. ) The brake pad actuating device of claim 1, wherein the internal wall does not travel past a seal groove when pressure is applied to the piston.

12. ) The brake pad actuating device of claim 1, wherein the wall thickness of the second pocket of the piston is reduced resulting in a lower piston mass.

13. ) The brake pad actuating device of claim 1, wherein the wall thickness of the inner wall of the piston is increased resulting in a lower fluid displacement.

14. ) The pad actuating device of claim 1, wherein the wall thickness of the second pocket is reduced and the inner wall thickness is increased resulting in lower fluid displacement and unchanged mass.

15. ) The brake pad actuating device of claim 1, wherein the wall thickness of the first pocket is greater than the wall thickness of the second pocket.

16. ) The brake pad actuating device of claim 1, wherein the draft angle of the second pocket and the first pocket are reduced.

17. ) The brake pad actuating device of claim 1, wherein the piston is made of a phenolic resin or Acrylonitrile butadiene styrene (ABS).

18. ) The brake pad actuating device of claim 1, wherein the internal wall is located between the first pocket and the second pocket so that the depth of both the first pocket and the second pocket are substantially the same.

19. ) The brake pad actuating device of claim 1, wherein the piston does not include a closed end.

20. ) A brake pad actuating device comprising:

a) a cylindrical piston adapted for use as a brake piston including;

i) a first pocket;

ii) an opposing second pocket;

iii) an internal wall located in the piston separating the first pocket and the second pocket; and

iv) an annular boot groove located in the cylindrical piston adjacent to the first pocket;

wherein the volume of the first pocket to the volume of the second pocket form a ratio of about 5;

1 or less;

wherein the cylindrical piston is made of a moldable plastic material that does not dissolve in brake fluid, and the cylindrical piston is sufficiently rigid to withstand fluid pressure that pushes the cylindrical piston into contact with an inboard brake pad;

wherein brake fluid fills the second pocket and surrounds the cylindrical piston so that equal amounts of force, in the radial direction, are exerted on an inside of the cylindrical piston and an outside of the cylindrical piston; and

wherein the inner wall of the cylindrical piston is located in proximity to a seal groove when the brake pads are fully worn, and the piston is in a fully extended position.