Variable wedge of electro wedge brake, and device and method of adjusting wedge angle

Patent metadata

Field	Value
Publication number	US-9759280-B2
Application number	US-201615007336-A
Country	US
Kind code	B2
Filing date	Jan 27, 2016
Priority date	May 8, 2015
Publication date	Sep 12, 2017
Grant date	Sep 12, 2017

Abstract

Provided are a wedge angle adjusting device and method. A device for adjusting a wedge angle of a variable wedge of an electro wedge brake (EWB) includes a movable wedge including an inclined surface and a counter wedge which includes an inclined surface disposed to face the inclined surface of the movable wedge and is disposed to face the movable wedge. The wedge angle adjusting device includes a frictional coefficient estimate unit configured to estimate a frictional coefficient between a pad and a disc of the EWB, a wedge angle command unit configured to calculate a wedge angle command value, based on a estimation of frictional coefficient estimated by the frictional coefficient estimate unit, and a wedge control unit configured to adjust the wedge angle according to the calculated wedge angle command value.

First claim

What is claimed is:

1. A device for adjusting a wedge angle of a variable wedge of an electro wedge brake (EWB) which includes a movable wedge, including an inclined surface, and a counter wedge, which includes an inclined surface disposed to face the inclined surface of the movable wedge and is disposed to face the movable wedge, the device comprising:
a frictional coefficient estimate unit configured to estimate a frictional coefficient between a pad and a disc of the EWB;
a wedge angle command unit configured to calculate a wedge angle command value, based on the frictional coefficient estimated by the frictional coefficient estimate unit; and
a wedge control unit configured to adjust the wedge angle according to the calculated wedge angle command value,
wherein the wedge angle command unit calculates the wedge angle command value “α command ” by using Equation below:

α
command

=

a
⁢

⁢

tan
⁡

(

μ
~

i

+

F
ai

F
ni

)

where {tilde over (μ)} i means the frictional coefficient estimated by the frictional coefficient estimate unit, F ai means an actuating force which is applied to the movable wedge at an i-th sampling time, F ni means a clamping force which is applied to the pad at the i-th sampling time, wherein i is an integer equal to or greater than one.

2. The device of claim 1 , wherein the frictional coefficient estimate unit estimates the frictional coefficient “{tilde over (μ)} i ” by using Equation below:

μ
~

i

=

tan
⁢

⁢

α

i
-
1

-

F

α
⁢

⁢
i

F
ni

where F ai means the actuating force which is applied to the movable wedge at the i-th sampling time, F ni means the clamping force which is applied to the pad at the i-th sampling time according to movement of the counter wedge, and α i-1 means a measurement wedge angle which is measured at an (i−1)-th sampling time.

3. A method of adjusting a wedge angle of an electro wedge brake (EWB) which includes a movable wedge including an inclined surface and a counter wedge which includes an inclined surface disposed to face the inclined surface of the movable wedge and is disposed to face the movable wedge, the method comprising:
estimating a frictional coefficient between a pad and a disc of the EWB;
calculating a wedge angle command value, based on an estimated frictional coefficient; and
adjusting the wedge angle according to the calculated wedge angle command value,
wherein the calculating comprises calculating the wedge angle command value “α command ” by using Equation below:

α
command

=

a
⁢

⁢

tan
⁡

(

μ
~

i

+

F
ai

F
ni

)

where {tilde over (μ)} i means the frictional coefficient estimated by the frictional coefficient estimate unit, F ai means the actuating force which is applied to the movable wedge at the i-th sampling time, and F ni means the clamping force which is applied to the pad at the i-th sampling time.

4. The method of claim 3 , wherein
the EWB comprises a variable wedge including: a movable shaft that has a bar shape and is parallel to a bottom of the counter wedge; a linear motion driving part that is connected to one side of the movable shaft to linearly move the movable shaft in parallel with the bottom of the counter wedge; a fixed hinge that is fixed to a certain position of an upper portion of the inclined surface of the counter wedge; and a rotation shaft that has a bar shape and is connected to the fixed hinge at first side of the rotation shaft and connected to the movable shaft at a second side, and
the adjusting comprises:
moving, by the linear motion driving part, the movable shaft in a direction toward the rotation shaft to increase the wedge angle; and
moving, by the linear motion driving part, the movable shaft in a direction opposite to the rotation shaft to reduce the wedge angle.

5. The method of claim 4 , wherein the adjusting comprises:
in increasing the wedge angle, subtracting

Δ
⁢

⁢

y
FIX

tan
⁢

⁢

α
command

from an initial x axis length “Δx 0 ” of when the linear motion driving part is located at a predetermined start point, and
in reducing the wedge angle, subtracting the initial x axis length “Δx 0 ”, corresponding to when the linear motion driving part is located at the predetermined start point, from

Δ
⁢

Assignees

• Daegu Gyeongbuk Inst Science & Tech

Inventors

• Shin Dong Hwan
• Jin Sung Ho
• Lee Seong Hun
• Jeong Choong Pyo

Classifications

• F16D2121/14

  Mechanical · CPC title

• F16D65/183 Primary

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

• F16D2127/10

  having wedging elements · CPC title

• F16D55/14

  with self-tightening action, e.g. by means of coacting helical surfaces or balls and inclined surfaces · CPC title

• F16D2121/24

  using motors · CPC title