Vehicle brake pad and method of production thereof

Patent metadata

Field	Value
Publication number	US-12590853-B2
Application number	US-202118007915-A
Country	US
Kind code	B2
Filing date	May 21, 2021
Priority date	Jun 5, 2020
Publication date	Mar 31, 2026
Grant date	Mar 31, 2026

Abstract

A vehicle brake pad ( 100 ) comprising: a support plate ( 21 ); a friction pad ( 20 ); at least a shear force sensing device; and an electrical circuit configured to collect signals from the shear force sensing device ( 1 ); wherein the shear force sensing device ( 1 ) comprises: a sheet ( 2 ) of piezoelectric material having a first and a second main faces ( 3, 4 ) parallel to each other identifying a shear stress direction(S); at least a first digitated reading electrode ( 5 ) located on the first main face ( 3 ); at least a second digitated reading electrode ( 6 ) located on the second main face ( 4 ), the first and second reading electrodes ( 5, 6 ) having digits ( 5 a, 6 a ) aligned along a reading direction (R) orthogonal to the stress shear direction(S); at least a first digitated polarizing electrode ( 7 ) located on the first main face ( 3 ) and interdigitated with the first digitated reading electrode ( 5 ); and at least a second digitated polarizing electrode ( 8 ) located on the second main face ( 4 ) and interdigitated with the second digitated reading electrode ( 6 ); and wherein the piezoelectric material has a bulk electric polarization with vector field (E) transversally oriented to the reading direction (R), each pair of aligned digits ( 5 a, 6 a ) of the first and second reading electrodes ( 5, 6 ) enclosing a respective zone ( 2 a ) of the piezoelectric material having the vector field (E) most tangentially oriented to the shear stress direction(S).

First claim

The invention claimed is:

1 . A vehicle brake pad comprising:
a support plate; a friction pad; at least a shear force sensing device; and an electrical circuit configured to collect signals from said at least a shear force sensing device; wherein said shear force sensing device comprises: a piezoelectric material comprising a first face and a second faces opposite the first face, the first and second faces extending parallel to each other in a shear stress direction; a first reading electrode positioned on the first face and comprising a first reading digit; a second reading electrode positioned on said second face and comprising a second reading digit, said first and second reading electrodes aligned with each other along a reading direction that is orthogonal to said stress shear direction; a first polarizing electrode positioned on said first main face and interdigitated with said first reading electrode; a second polarizing electrode positioned on said second face and interdigitated with said second reading electrode; in a first region of said shear force sensing device, said piezoelectric material has a polarization vector field that is transversally oriented to said reading direction, in a second region of said shear force sensing device, said piezoelectric material has a polarization vector field that is tangentially oriented relative to said shear stress direction wherein said first polarizing electrode comprises a first polarizing digit, and said second polarizing electrode comprises a second polarizing digit, and wherein said first and second reading digits are larger than digits of said first and second polarizing electrodes.

2 . The vehicle brake pad according to claim 1 , wherein said sheet of piezoelectric material comprises a screen-printed layer.

3 . The vehicle brake pad according to claim 1 , wherein said first and second reading electrodes and said first and second polarizing electrodes comprises a screen-printed layer.

4 . The vehicle brake pad according to claim 1 , wherein:
said first polarizing electrode comprises a first polarizing digit, said second polarizing electrode comprises a second polarizing digit and said first and second polarizing digits are at offset distance in said shear stress direction.

5 . The vehicle brake pad according to claim 1 , wherein said first and second reading electrodes are positioned between said first and a second polarizing electrodes along said stress shear direction.

6 . The vehicle brake pad according to claim 1 , wherein a width of said first and second reading digits is within a range between 60% and 85% of a distance between said first and second polarizing electrodes.

7 . A vehicle brake pad comprising:
a support plate; a friction pad; at least a shear force sensing device; and an electrical circuit configured to collect signals from said at least a shear force sensing device; wherein said shear force sensing device comprises: a piezoelectric material comprising a first face and a second face opposite said first face, said first and second faces extending parallel to each other along a shear stress axis; a first reading electrode positioned on said first face and comprising a first reading digit; a second reading electrode positioned on said second face and comprising a second reading digit; a first polarizing electrode positioned on said first face, said first polarizing electrode comprising a first polarizing digit; and a second polarizing electrode positioned on said second face, said second polarizing electrode comprising a second polarizing digit; wherein, along said shear stress axis, said first reading digit and said second reading digit are positioned between said first polarizing digit and said second polarizing digit, and wherein said first and second reading digits are larger than digits of said first and second polarizing electrodes.

8 . The vehicle brake pad according to claim 7 , wherein said first and second reading digits are aligned from each other along a reading direction that is orthogonal to said shear stress axis.

9 . The vehicle brake pad according to claim 7 , wherein said first and second polarizing digits are offset from each other along said shear stress axis.

10 . The vehicle brake pad according to claim 7 , wherein:
said first reading electrode further comprises a second first reading digit; said first polarizing electrode further comprises a second first polarizing digit; and along said shear stress axis, said first reading digit and said second first reading digit are positioned between said first polarizing digit and said second first polarizing digit.

11 . The vehicle brake pad according to claim 7 , wherein said first and second polarizing electrodes are configured to induce a field that is substantially parallel to said shear stress axis.

12 . The vehicle brake pad according to claim 7 , wherein a width of said first and second reading digits is within a range between 60% and 85% of a distance between said first and second polarizing digits.

13 . The vehicle brake pad according to claim 7 , wherein each of said first and second reading electrodes and said first and second polarizing electrodes ( 7 , 8 ) comprises a screen-printed layer.

14 . A method of manufacturing a vehicle brake pad, the method comprising:
mating an electrical circuit on a support plate; mating a piezoelectric assembly on said electrical circuit, wherein obtaining said piezoelectric assembly comprises:
mating a first reading electrode to a first face of a piezoelectric material, said first reading electrode comprising a first reading digit;
mating a first polarizing electrode comprising a first polarizing digit to said first face of said piezoelectric material;
mating a second reading electrode to a second face of said piezoelectric material, said second reading electrode comprising a second reading digit; and
mating a second polarizing electrode comprising a second polarizing digit to said second face said piezoelectric material;
wherein said first and second polarizing electrodes are offset along said shear stress direction; and
wherein said first and second digits being aligned along a reading direction that is orthogonal to said stress shear direction;
wherein said first and second reading digits are larger than digits of said first and second polarizing electrodes;
mating a friction pad on said support plate; and
polarizing said piezoelectric assembly, wherein polarizing said piezoelectric assembly comprises:
supplying electric power to said first and second polarizing electrodes; and
generating a vector field that is substantially parallel to said shear stress direction in a region between said first and second digits,
and wherein polarizing said piezoelectric assembly further comprises maintaining said first and second reading electrodes at a floating potential.

15 . The method according to the claim 14 , wherein mating said first reading electrode and said first polarizing electrode to said first face of said piezoelectric material comprise screen-printing said first reading electrode and said first polarizing electrode to said first face of said piezoelectric material.

Assignees

• Itt Italia Srl

Inventors

• Serra Stefano
• Vignolo Umberto
• Terranova Marco

Classifications

• G01L5/28

  for testing brakes · CPC title

• F16D2250/0084

  Assembly or disassembly · CPC title

• F16D2066/006

  without direct measurement of the quantity monitored, e.g. wear or temperature calculated form force and duration of braking · CPC title

• F16D2066/005

  Force, torque, stress or strain · CPC title

• F16D66/00

  Arrangements for monitoring working conditions, e.g. wear, temperature · CPC title