Method for manufacturing a braking element with integrated sensor, in particular a brake pad, brake pad with integrated sensor, vehicle braking system and associated method

Patent metadata

Field	Value
Publication number	US-9415757-B2
Application number	US-201314106262-A
Country	US
Kind code	B2
Filing date	Dec 13, 2013
Priority date	Apr 17, 2013
Publication date	Aug 16, 2016
Grant date	Aug 16, 2016

Abstract

A method in which at least one piezoceramic sensor, which converts every mechanical force to which it is subjected into an electrical signal and having a Curie temperature higher than 200° C., is solidarized directly onto the surface of a metal support element of a vehicle braking element, which during use faces a vehicle element to be braked. While in contact with such a surface, an electrical circuit is implemented that picks up and eventually processes the electrical signal, the electrical circuit being connected with a connector integrated with the metal support element. An electrically insulating layer sandwiches the at least one piezoceramic sensor and the electrical circuit, and a block of friction material with an underlying damping layer is formed upon the electrically insulating layer. After forming the block of friction material, the piezoceramic sensor is polarized by applying a predetermined potential difference thereto by means of the connector.

First claim

The invention claimed is:

1. A method for manufacturing sensorized brake elements for vehicles, comprising the steps of:
a) making at least one piezoceramic sensor integral directly with and onto a first surface of a metal support element of a braking element which is intended during use to be directed towards a vehicle element to be braked, the at least one piezoceramic sensor being able to convert mechanical energy received in a polarization direction of the at least one sensor, when subjected to a mechanical force, into electrical energy for emitting an electrical signal due to piezoelectric effect, the at least one sensor being selected from a group of piezoceramic sensors still operational at working temperatures at least equal to or greater than 200° C. and free from polymeric active components;
b) providing an electrical circuit which is in contact with said first surface, to pick up said electrical signal and possibly processing the electrical signal and connecting said electrical circuit with a connector made integral with said metal support element;
c) providing an electrically insulating layer, which is one of continuous or discontinuous, on the first surface so as to sandwich the at least said one piezoceramic sensor and said electrical circuit between the first surface and the electrically insulating layer, so as to embed them within said electrically insulating layer;
d) providing a dampening and thermally insulating layer directly onto said electrically insulating layer and on the first surface so that the at least one piezoceramic sensor is directly and completely embedded within the dampening and thermally insulating layer with the interposition of the electrically insulating layer; and
e) forming a block of friction material upon the dampening and thermally insulating layer, said block being held stiff by the metal support element.

2. A method according to claim 1 further comprising the step of:
f) applying a predetermined potential difference to said at least one piezoceramic sensor after the step of forming the block of friction material and by means of said connector, so as to at least one of polarize and re-polarize the piezoceramic material of said at least one piezoceramic sensor.

3. A method according to claim 1 , wherein the at least one piezoceramic sensor is selected so as to have a thickness equal to or less than that of the dampening and thermally insulating layer, when measured perpendicular to said first surface.

4. A method according to claim 1 , wherein the at least one piezoceramic sensor is formed in situ directly upon said first surface and is exclusively made of a piezoceramic material having a Curie temperature higher than 200° C.

5. A method according to claim 1 , further comprising making a plurality of piezoceramic pressure sensors integral with said first surface and arranging the plurality of sensors in a spaced apart configuration as a symmetric array, so as to discretely occupy the whole of said first surface, at least one of said sensors being provided to respond to forces that are transverse to a direction of application in use of the pressure onto the braking element; said plurality of sensors being connected to one another and to at least one of said connector by means of said electrical circuit, which is obtained directly onto the first surface before integrating therein said plurality of sensors.

6. A method according to claim 5 , said electrical circuit further comprising means for processing voltage or electric charge signals produced by said plurality of piezoceramic sensors.

7. A method according to claim 2 , wherein said polarizing/re-polarizing step of the at least one piezoceramic sensor is carried out by applying a potential difference of between 0.1 and 5 kV for a predetermined time period between 5 and 10 seconds using said connector, said potential difference being applied to opposing sensor electrode poles for each millimeter of thickness of piezoceramic material of which the sensor is made, as measured in the polarization direction of the sensor itself.

8. Method as claimed in claim 1 , wherein an electric cable terminated by said connector is provided integral with said metal support element to connect said electrical circuit with said connector.

9. A braking element with an integrated sensor, said braking element comprising:
a metal support element;
a dampening and thermally insulating layer arranged on one side of a first surface of the metal support element intended during use to face towards a vehicle element to be braked;
a block of friction material held stiff by the metal support element on one side of said first surface and above said dampening and thermally insulating layer;
at least one piezoceramic sensor made of a piezoceramic material having a Curie temperature higher than 200° C., which has been directly made integral with and onto the first surface of the metal support element;
an electrical circuit for picking up an electrical signal emitted by the at least one piezoceramic sensor due to piezoelectric effect and optionally processing the electrical signal, provided so as to be in contact with the first surface and connected to a connector, which is made integral with said metal support element; and
a continuous or discontinuous electrically insulating layer arranged directly onto said first surface and directly underneath said dampening and thermally insulating layer, said at least one piezoceramic sensor and said electrical circuit being sandwiched between the first surface of the metal support element and the electrically insulating layer, with said block of friction material and the dampening and thermally insulating layer arranged thereon, in such a manner that the at least one piezoceramic sensor is directly and completely embedded within the dampening and insulating layer with the interposition of the electrically insulating layer; and said connector and electrical circuit being adapted to be connected to a voltage generation means in order to polarize said at least one piezoceramic sensor.

10. A braking element with an integrated sensor, said braking element comprising:
a metal support element;
a dampening and thermally insulating layer arranged on one side of a first surface of the metal support element intended during use to face towards a vehicle element to be braked;
a block of friction material held stiff by the metal support element on one side of said first surface and above said dampening and thermally insulating layer;
at least one pressure sensor made of a piezoceramic material having a Curie temperature higher than 200° C., which has been directly made integral with and onto the first surface of the metal support element;
an electrical circuit for picking up an electrical signal emitted by the at least one pressure sensor due to piezoelectric effect and optionally processing the electrical signal, provided so as to be in contact with the first surface and connected to a connector, which is made integral with said metal support element; and
a continuous or discontinuous electrically insulating layer arranged directly onto said first surface and directly underneath said dampening and thermally insulating layer, said at least one sensor and said electrical circuit being sandwiched between the first surface of the metal support element and the electrically insulating layer, with said block of friction material and the dampening and thermally insulating layer arranged thereon, in such a manner that the at least one pressure sensor is directly and completely embedded within the dampening and insulating layer with the interposition of the electrically insulating layer; and said connector and electrical circuit being adapt

Assignees

• Itt Italia Srl

Inventors

• Martinotto Luca
• Merlo Fabrizio
• Donzelli Daniele

Classifications

• G01L5/28

  for testing brakes · CPC title

• F16D65/08

  for internally-engaging brakes · CPC title

• F16D65/0006

  Noise or vibration control · CPC title

• F16D2066/001

  Temperature · CPC title

• G01L1/16

  using properties of piezoelectric devices · CPC title