Brake piston

Patent metadata

Field	Value
Publication number	US-10184536-B2
Application number	US-201615274270-A
Country	US
Kind code	B2
Filing date	Sep 23, 2016
Priority date	Sep 23, 2016
Publication date	Jan 22, 2019
Grant date	Jan 22, 2019

Abstract

A brake piston assembly including a brake piston; a rotary to linear stage mechanism including a spindle and a nut; and a ball ramp assembly including a nut ramp plate and a piston ramp plate. The brake piston includes a piston pocket. The ball ramp assembly is located at a bottom wall of the piston pocket. The ball ramp assembly engages a side wall of the piston pocket so that the ball ramp assembly is maintained in the piston pocket after the ball ramp assembly is assembled in the piston pocket. Rotation of the spindle causes the nut to axially move until the nut directly contacts the nut ramp plate, and further axial movement of the nut causes the nut to move the ball ramp assembly and the brake piston against an inboard brake pad to create a clamp force.

First claim

The invention claimed is:

1. A brake piston assembly, comprising:
a) a brake piston;
b) a rotary to linear stage mechanism comprising a spindle and a nut; and
c) a ball ramp assembly comprising a nut ramp plate and a piston ramp plate;
wherein the brake piston comprises a piston pocket, the piston pocket comprises a bottom wall and a side wall, the ball ramp assembly is located adjacent the bottom wall of the piston pocket, and
wherein the nut comprises a rubber clutch that is configured to engage the side wall of the piston pocket and restrict rotation of the nut about a longitudinal axis of the brake piston during rotation of the spindle and creation of a clamp force.

2. The brake piston assembly according to claim 1 , wherein the rotation of the spindle causes the nut to axially move until the nut directly contacts the nut ramp plate, and further axial movement of the nut by way of the rotation of the spindle causes the nut to move the ball ramp assembly and the brake piston against an inboard brake pad to create the clamp force, and
wherein the clamp force is created to apply a parking brake.

3. The brake piston assembly according to claim 1 , wherein the ball ramp assembly comprises at least one rolling element that is located between the piston ramp plate and the nut ramp plate,
wherein the engagement between the rubber clutch and the side wall of the piston pocket is configured to slip as the clamp force increases so that the nut begins to rotate with the rotation of the spindle about the longitudinal axis, which causes the nut ramp plate to also rotate about the longitudinal axis, which causes the at least one rolling element to axially separate the piston ramp plate from the nut ramp plate, and
wherein the axial separation of the piston ramp plate from the nut ramp plate causes the brake piston to move an inboard brake pad to increase the clamp force.

4. The brake piston assembly according to claim 1 , wherein the ball ramp assembly comprises a spring, the spring is adapted to maintain a load on the ball ramp assembly, and
wherein the spring is fixed to both the nut ramp plate and the piston ramp plate.

5. The brake piston assembly according to claim 1 , wherein the ball ramp assembly comprises a spring retainer and a spring,
wherein the spring is adapted to maintain a compressive load on the ball ramp assembly, and
wherein the spring retainer is fixed to the nut ramp plate and a flange on the spring retainer.

6. The brake piston assembly according to claim 1 , wherein the nut is keyed to an inner portion of the nut ramp plate so that the nut and the nut ramp plate are free from rotating independently of one another,
wherein the ball ramp assembly comprises a stopper, the stopper is adapted to engage a groove in the side wall of the piston pocket,
wherein the ball ramp assembly includes a spring, the spring is fixed between the stopper and the nut ramp plate, and
wherein the spring is adapted to maintain a preload on the ball ramp assembly, which restricts rotation of the nut and the nut ramp plate during the rotation of the spindle.

7. The brake piston assembly according to claim 1 , wherein the nut ramp plate and the piston ramp plate comprise at least one set of corresponding ramps,
wherein each of the corresponding ramps comprise a first portion and a second portion,
wherein as the clamp force increases, the nut ramp plate rotates about an axis which causes a rolling element to move up the corresponding ramps from the first portion to the second portion, which causes the nut ramp plate and the piston ramp plate to axially separate,
wherein a slope of the first portion is greater than a slope the second portion.

8. The brake piston assembly according to claim 7 , wherein each of the corresponding ramps comprise a third portion,
wherein as the clamp force increases, the nut ramp plate rotates about the axis which causes the rolling element to move up the corresponding ramps from the first portion to the second portion and then from the second portion to the third portion so that the nut ramp plate and the piston ramp plate further axially separate.

9. The brake piston assembly according to claim 8 , wherein the slope of the first portion is greater than the slope the second portion and also greater than a slope of the third portion.

10. The brake piston assembly according to claim 1 , wherein the ball ramp assembly comprises a rubber clutch that is adapted to engage the side wall of the piston pocket.

11. A brake system comprising:
a brake caliper comprising:
a) the brake piston assembly according to claim 1 , the brake piston assembly is located in a caliper bore of the brake caliper, and
b) a motor gear unit, the motor gear unit is in communication with the spindle;

wherein the piston ramp plate comprises a rubber clutch that is adapted to engage the side wall of the piston pocket,
wherein the motor gear unit is adapted to rotate the spindle, which causes the nut to axially advance until the nut directly contacts the nut ramp plate, and further rotation of the spindle causes the nut to move the ball ramp assembly and the brake piston against an inboard brake pad and the inboard brake pad against a brake rotor to create the clamp force.

12. The brake system according to claim 11 , wherein the nut ramp plate and the piston ramp plate comprise at least one set of corresponding ramps,
wherein as the clamp force increases, the nut ramp plate rotates about an axis which causes a rolling element to move up the corresponding ramps so that the nut ramp plate and the piston ramp plate separate,
wherein each of the ramps comprise a first portion and a second portion, and
wherein a slope of the first portion is greater than a slope the second portion.

13. The brake system according to claim 12 , wherein the second portion comprises a plurality of intermittent sections, and between each of the intermittent sections the corresponding ramps comprise a flat section, a slope of each of the flat sections is generally zero.

14. The brake system according to claim 13 , wherein each of the ramps comprise four flat sections.

15. The brake system according to claim 11 , wherein the ball ramp assembly comprises a spring, the spring is adapted to engage both the piston ramp plate and the nut ramp plate, and
wherein the spring is in tension during creation of the clamp force.

16. The brake system according to claim 11 , wherein the ball ramp assembly comprises a spring, the spring engages both the piston ramp plate and the nut ramp plate, and
wherein the spring is in compression during creation of the clamp force.

17. A method of assembling a brake piston assembly, the method comprising steps of:
a) inserting a ball ramp assembly into a piston pocket of a brake piston; and
b) inserting a rotary to linear stage mechanism into the piston pocket so that a nut of the rotary to linear stage mechanism contacts the ball ramp assembly, the nut comprises a rubber clutch that is configured to engage a side wall of the piston pocket;
wherein the ball ramp assembly comprises a piston ramp plate and a nut ramp plate, and after the step of a), a clutch of the piston ramp plate is adapted to engage the side wall of the piston pocket so that the ball ramp assembly is maintained in the piston pocket.

18. The method of claim 17 , wherein the ball ramp assembly comprises a spring retainer that maintains together the nut ramp plate, the piston ramp plate and a plurality of rolling elements between the piston ramp plate and the nut ramp plate s

Assignees

• Akebono Brake Ind

Inventors

• Chelaidite Galus
• Suzuki Michio

Classifications

• F16D2125/06

  Pistons · CPC title

• F16D2125/40

  Screw-and-nut · CPC title

• F16D2121/04

  acting on a piston-type actuator, e.g. for liquid pressure · CPC title

• F16D65/183 Primary

  with force-transmitting members arranged side by side acting on a spot type force-applying member · CPC title

• F16D55/226

  in which the common actuating member is moved axially {, e.g. floating caliper disc brakes} · CPC title