System for detecting operating state conditions associated with a pad of a disc brake of a vehicle

Abstract

The invention relates to a system (100) for detecting operating state conditions associated with a pad (1) of a brake disc (10) of a braking system of a vehicle. The disc brake comprises: - a brake disc (2) having a first body (22) adapted to rotate integrally with a wheel of the vehicle; - a brake caliper (3), static with respect to said brake disc, configured to apply a clamping force to the brake disc during a braking event, said brake caliper having a second body (33) provided with at least one surface (33') facing the first body of the rotating brake disc; - the aforesaid pad is made of a consumable friction material; such a pad is operatively associated with said brake caliper (3) and has a respective body (11) including a first surface (12) and an opposite second surface (13) parallel to the first surface and located at a distance (d) from the first surface; the second surface is configured to be in contact with the first body of the brake disc upon clamping the brake caliper on the brake disc; the body of the pad includes a third connecting surface (14; 14') between the first and second surfaces. The detecting system comprises: - at least one sensor (50) applied directly to the third connecting surface of the pad, wherein the at least one sensor comprises at least one resistive element (51; 61; 71; 81; 91) printed directly on the third surface of the pad by means of Aerosol Jet Printing methodology or "additive manufacturing" technology or "screen printing" technology; the at least one sensor is configured to detect the wear of the consumable friction material of the pad upon reducing said distance between the first and second surfaces of the pad, and to generate at least one electrical signal (SIG) representative of the detected wear; - electronic interrogation and detection means (60) operatively associated with the at least one sensor, adapted to send at least a first electrical signal (SIG1) for enabling the detection of wear by the sensor and for receiving the at least one electrical response signal generated by the sensor.

Description

DESCRIPTION"SYSTEM FOR DETECTING OPERATING STATE CONDITIONS ASSOCIATED WITH APAD OF A DISC BRAKE OF A VEHICLE"

[0001] . Field of the invention

[0002] . The present invention relates to the field of vehicle braking systems. In particular, the invention relates to a system for detecting operating state conditions associated with a pad of a brake disc of the braking system of a vehicle. Such detected operating state conditions of the pad include: a measurement of the wear of the friction material of the pad; a measurement of the temperature of the pad.

[0003] . Background art

[0004] . For controlling and monitoring a braking system, e.g., an electronically controlled disc brake system, it is very useful to know a degree of wear of the friction material which forms the disc brake pads following the repetition of one or more braking actions in real-time and as accurately as possible.

[0005] . In order to detect the degree of wear of the disc brake pads, the systems of the known type employ wear sensors which allow detecting only when the pad reaches a maximum degree of wear, i.e., they allow detecting when the friction material of the pad has reached an unacceptable level of wear for the correct operation of the braking system and a maintenance intervention is required to replace the pad.

[0006] . Such pad wear sensors of the known type are generally made in one piece which is assembled on the pad before the latter is mounted on the brake caliper. In particular, it is assembled by gluing or by means of spring retention.

[0007] . The aforementioned methods of assembling wear sensors to pads are not free from defects.

[0008] . Indeed, the wear sensors glued to the pad are not very robust, in particular when such sensors are used under high temperature conditions or in environments prone to contamination. The use under such operating conditions can cause the sensor head to detach from the pad body, and as a result the detection of the pad wear is incorrect.

[0009] . Although the wear sensors mounted to the pad body with a spring retention mechanism are more robust when used under high temperature conditions or in environments prone to contamination, such sensors have other drawbacks during normal operation. Indeed, an effect of clearance associated with the head of such sensors can cause noise and vibration problems which degrade comfort for the vehicle occupants.

[0010] . Although the technical field of sensor technology offers a wide range of solutions, to the best of the Applicant's knowledge, there are currently no system solutions including sensors to be incorporated into a brake disc, and that would allow knowing the degree of wear of the friction material of the pad of the brake disc following the repetition of one or more braking actions in real-time with high accuracy and reliability.

[0011] . Thus, the need arises for a system for detecting the degree of wear of the friction material of the pad of a disc brake which, by employing compact, miniaturized sensors, which are easy to activate / read, allows determining the presence of wear of such a pad with high accuracy and reliability.

[0012] . As already noted above, such needs are not fully met by the solutions currently available from the prior art.

[0013] . Solut ion

[0014] . It is an object of the present invention to devise and provide a system for detecting operating state conditions associated with a pad of a disc brake of the braking system of a vehicle. In particular, the invention relates to a system that, by detecting the degree of wear of the friction material of the pad of a disc brake, allows overcoming, at least partially, the limitations and drawbacks of the solutions available in the prior art .

[0015] . Such an object is achieved by a system for detecting operating state conditions associated with a pad of a disc brake of the braking system of a vehicle according to claim 1.

[0016] . It is a further object of the invention to provide a system that also allows obtaining and providing a measurement of the temperature of the pad of a disc brake of the braking system of a vehicle.

[0017] . The invention relates to a resistive sensor obtained by printing the active part of the sensor directly on the surface ofthe pad friction material. Such a sensor is configured to detect the wear of the pad friction material continuously because a variable resistance value offered by such a sensor is representative of the pad wear.

[0018] . The use of such a sensor is particularly advantageous for monitoring the condition of the vehicle, because it allows continuously monitoring the wear state of the friction material of the disc brake pads, and for managing a periodic vehicle maintenance schedule.

[0019] . The present invention solves the problems of the known solutions since the sensor itself is printed on the consumable area of the pad and there are no glued or assembled parts which can detach or move during the braking event, generating noise.

[0020] . The electrical connection of the printed sensor to the wiring can be made by soldering or by means of pad-spring contacts according to the requirements of the application and the geometry and layout of the pad, but both are reliable solutions because the interconnection points are kept outside the wear area of the pad.

[0021] , The invention also relates to a method for detecting and measuring the wear of the friction material of a disc brake pad, according to claim 17.

[0022] , The invention also relates to a method for detecting and measuring the temperature of a disc brake pad, according to claim 19.

[0023] . Other advantageous embodiments are the subject of thedependent claims .

[0024] . Figures

[0025] . Further features and advantages of the system for detecting operating state conditions associated with a pad of a disc brake of the braking system of a vehicle of the invention will become apparent from the description provided below of preferred embodiments thereof, given by way of non-limiting indication, with reference to the accompanying drawings, in which:

[0026] . - figure 1 diagrammatically shows an enlarged view of an embodiment of the system for detecting operating state conditions associated with a disc brake pad of the braking system of a vehicle of the invention, such as the degree of wear of the pad friction material, for example, in which the detecting components of the system are at least partially associated with a connecting surface of the pad bodybetween a first surface of the pad and an opposite second surface, parallel to such a first surface;

[0027] . - figure 1A shows a perspective view of a brake disc and a brake caliper of a vehicle braking system, in which surfaces of the caliper facing the moving brake disc, in which the detecting components in figure 1 can be placed, are shown;

[0028] . - figure 2 shows a first embodiment of a sensor of the system of the invention which comprises at least one resistive element printed on the connecting surface of the pad body in figure 1;

[0029] . - figures 2A-2B show changes in the resistance detectedby the sensor in figure 2 following an increase in wear of the pad friction material, when such at least one resistive element comprises sixteen and forty-eight parallel metal tracks, respectively, each having a resistance of 45 Ohm;

[0030] . - figure 3 shows a second embodiment of a sensor of the system of the invention which comprises at least one resistive element printed on the connecting surface of the pad body in figure 1;

[0031] . - figure 3A shows a change in the resistance detected by the sensor in figure 3 following a reduction of a width of the sensor caused by the increase in wear of the pad friction material ;

[0032] , - figure 4 shows a third embodiment of a sensor of the system of the invention which comprises at least one resistive element printed on the connecting surface of the pad body in figure 1;

[0033] . - figure 4A shows a change in the resistance detected by the sensor in figure 4 following a reduction of a width of the sensor caused by the increase in wear of the pad friction material ;

[0034] . - figure 5 shows a fourth embodiment of a sensor of the system of the invention which comprises at least one resistive element printed on the connecting surface of the pad body in figure 1;

[0035] . figure 5A shows a change in the resistance detected bythe sensor in figure 5 following a reduction of a width of the sensor caused by the increase in wear of the pad friction material ;

[0036] . - figure 6 shows a fifth embodiment of a sensor of the system of the invention, which comprises at least one resistive element printed on the connecting surface of the pad body in figure 1;

[0037] . - figure 6A shows a change in the resistance detected by the sensor in figure 6 following a reduction of a width of the sensor caused by the increase in wear of the pad friction material ;

[0038] . - figure 7 shows a first embodiment of a connection layout of one or more sensors in figures 2, 3, 4, 5, 6 with electronic interrogation and detection means;

[0039] . - figure 8 shows a second embodiment of a connection layout of one or more sensors in figures 2, 3, 4, 5, 6 with electronic interrogation and detection means;

[0040] . - figure 9 shows a perspective view of a third embodiment of a connection layout of one or more sensors in figures 2, 3, 4, 5, 6, associated with a connecting surface of the pad body, with electronic interrogation and detection means;

[0041] , - figure 10 shows a perspective view of a fourth embodiment of a connection layout of one or more sensors in figures 2, 3, 4, 5, 6, associated with a connecting surface of the pad body, with electronic interrogation and detection means;

[0042] . - figure 10A shows an enlarged view of a connecting portion of a pad sensor to electrical cables of the connection layout in figure 10;

[0043] . - figure 11 diagrammatically shows a side view of a sensor in figures 2, 3, 4, 5, 6, which comprises at least one resistive element, printed directly on the connecting surface of the pad body in figure 1 for detecting the degree of wear of the pad friction material and an additional resistive element printed directly on such a surface to detect a pad temperature;

[0044] , - figure 12 shows a first electronic circuit, in a halfbridge configuration, for measuring the resistance associated with the printed sensor in figure 11 which is representative of the degree of wear of the pad friction material;

[0045] . - figure 13 shows a second electronic circuit in a quarter-bridge configuration for measuring the resistance associated with the additional printed resistive element in figure 11 which is representative of the pad temperature;

[0046] . - figures 14-14A shows front and side views of a further example of a disc brake pad of the braking system of the invention, in which a portion of the pad surface, connecting a first surface fixed to the brake caliper and an opposite second surface parallel to the first surface, is inclined;

[0047] . - figure 15 shows, by means of a flowchart, operating steps of a method for detecting and measuring the wear of the friction material of a disc brake pad, implemented by the systemin figure 1;

[0048] . - figure 16 shows, by means of a flowchart, operating steps of a method for detecting and measuring the temperature of a disc brake pad, implemented by the system in figure 11.

[0049] . Similar or equivalent elements in the aforesaid figures are indicated by the same reference numerals.

[0050] . Description of some preferred embodiments

[0051] . With reference to figures 1, 1A, reference numeral 100 indicates as a whole a system, according to the present invention, for detecting operating state conditions associated with a pad 1 of a disc brake 10 of a vehicle brake system.

[0052] . The detected operating state conditions of the pad 1 include: a degree of wear of the consumable friction material which forms the pad 1, or temperature conditions of the pad itself. The system 100 for detecting the degree of wear of the consumable friction material forming the pad 1 is described in detail below. However, such a system 100 is also advantageously usable to detect a temperature measurement of the pad 1.

[0053] . For the purposes of the present description, "vehicle" means any motor vehicle or motorcycle, even of commercial type, having two, three, four, or more wheels. For example, vehicle means a motorcar, a motorbike, a light commercial vehicle, a heavy industrial vehicle or any other vehicle which requires a braking system to reduce the speed of the moving parts.

[0054] , Furthermore, "braking system" means the whole of all thecomponents (from mechanical and / or electric or electronic components up to the brake fluid) which contribute to generating the service braking of a vehicle.

[0055] . In particular, the system 100 for detecting operating state conditions of a pad 1 of the invention comprises the aforesaid disc brake 10. Such a disc brake 10 of the system 100 comprises a brake disc 2, having a first body 22 adapted to rotate integrally with a wheel of the vehicle, and a brake caliper 3, static with respect to such a brake disc 2, configured to apply a clamping force to the brake disc during a braking event. Such a brake caliper has a second body 33 provided with at least one surface 33' facing the first body 22 of the rotating brake disc 2.

[0056] . Furthermore, the disc brake 10 comprises the aforesaid pad 1, made of a consumable friction material. Such a pad 1 is operatively associated with the aforesaid brake caliper 3 and comprises a respective body 11, which includes a first pad surface 12 and an opposite second pad surface 13, parallel to such a first surface 12 and located at a distance d from the first surface. Note that such a first surface 12 of the pad 1 (not shown in figure 1) faces the caliper 3. The second surface 13 of the pad 1 is configured to be in contact with the first body 22 of the brake disc 2 upon clamping the brake caliper 3 on the brake disc 2. Furthermore, the body 11 of the pad 1 includes a third connecting surface 14, 14' between the first 12 and second 13 surfaces. A first example of connecting surface 14, orthogonal to the first 12and second 13 surfaces of the pad 1, is shown in figure 1. A second example of connecting surface 14' is described with reference to figures 14-14A.

[0057] . The detecting system 100 of the invention comprises at least one sensor 50 printed directly on the third connecting surface 14, 14' of the pad 1. Such at least one sensor 50 comprises at least one resistive element 51, 61, 71, 81, 91 printed on the third surface 14, 14' of the pad 1 by means of Aerosol Jet Printing methodology or "additive manufacturing" technology or "screen printing" technology. In particular, the present invention includes printing an electrically insulating layer or substrate on the third connecting surface 14, 14' of the pad 1 so as to isolate the active part of the sensor 50, i.e., the resistive element 51, 61, 71, 81, 91, from the friction material of the pad 1, which is a bad electrical insulator. The active part of the sensor 50 will be printed over this electrically insulating layer with conductive material using Aerosol Jet Printing methodology or "additive manuf cturing" or "screen printing" technology. An additional, final insulating layer will be preferably printed over the active part of the sensor 50 to isolate the sensor 50 from the external environment.

[0058] . Such at least one sensor 50 is configured to detect the wear of the consumable friction material of the pad 1 following the reduction of the aforesaid distance d between the first 12 and second 13 surfaces of the pad 1 and to generate at least oneelectrical signal SIG representative of the detected wear.

[0059] . The system 100 further comprises electronic interrogation and detection means 60 operatively associated with the at least one sensor 50, adapted to send at least a first electrical signal SIGI for enabling the detection of wear by the at least one sensor 50 and for receiving the at least one electrical response signal SIG generated by the sensor 50.

[0060] . In particular, the electronic interrogation and detection means 60 comprise at least one electronic circuit, either of the passive or active type, adapted to be connected to the printed sensor 50. For example, such an electronic circuit 60 of passive or active type comprises filtering and impedance matching circuit components or an application specific integrated circuit (ASIC) .

[0061] . Furthermore, the system 100 comprises a conductive connecting element 601 or wiring of the sensor 50, made by additive manufacturing methods, e.g., conductive connecting lines, adapted to connect such an electronic circuit 60 and the printed sensor 50. Such a wiring 601 is made at least partially, for example, on the body 11 of the brake pad of the disc brake 10.

[0062] . In an embodiment, the third connecting surface 14 mentioned above is orthogonal to the first 12 and second 13 surfaces of the pad 1.

[0063] . With reference to figures 14-14A, the aforesaid third connecting surface 14 of the pad 1 comprises at least one inclinedportion 14' with respect to both the first 12 and second 13 surfaces of the pad 1. In this case, the at least one sensor 50 is printed directly on the inclined portion 14' of the third connecting surface 14.

[0064] . With reference to figures 2, 3, 4, 5, 6, the at least one resistive element 51, 61, 71, 81, 91 of the sensor 50 printed directly on the third surface 14, 14' of pad 1 has a width La less than the distance d between the first surface 12 and the second surface 13, parallel to each other, of the body 11 of the pad 1. Such at least one resistive element 51, 61, 71, 81, 91 has an increasing resistance as such a width La decreases, caused by the reduction of the distance d between the first 12 and second 13 surfaces of the pad 1 induced by the consumption of the pad friction material following the braking actions.

[0065] . With reference to the embodiment in figure 2, the at least one printed resistive element 51 of the sensor 50 comprises a plurality of mutually parallel metal tracks 52 printed on a substrate made of electrically insulating material printed on the third surface 14, 14' of the body 11 of the pad 1. Each of such tracks has a first end 52' and a second end 52' ' connected to a first Cl and a second C2 conductor terminal, respectively, of the sensor 50 printed on the substrate made of electrically insulating material printed on the third surface 14, 14' of the body 11 of the pad 1 to electrically connect the aforesaid metal tracks 52 to the electronic interrogation and detection means 60, by means ofthe aforesaid conductive connecting element 601. Note that the parallel metal tracks 52 and the first Cl and second C2 conductor terminals are printed to remain rigidly applied to the substrate made of electrically insulating material. Such a substrate made of electrically insulating material has a thickness between 3 and 10 microns, for example.

[0066] . In an embodiment, the at least one printed resistive element 51 of the sensor 50 comprises sixteen metal tracks, each metal track 52 is 20mm long and 10 pm thick; or

[0067] , - the at least one printed resistive element 51 of the sensor 50 comprises forty-eight metal tracks, each metal track 52 is 20mm long and 10 pm thick.

[0068] . In particular, figures 2A-2B show how the resistance detected by the sensor 50 in figure 2 changes following an increase in wear, indicated by the arrow Fl, of the friction material of pad 1, i.e., the consumption of such a friction material, when such at least one resistive element 51 comprises sixteen and forty-eight parallel metal tracks, respectively, each having a resistance of 45 Ohm.There is an increase in strength as wear increases. Furthermore, with reference to the example in figure 2B, a reduction of the minimum and maximum resistances in favor of a higher resolution between the new pad condition and full wear, i.e., a more progressive increase in resistance with respect to wear, is noted.

[0069] , With reference to the embodiment in figures 3, 4, 5, 6,the at least one printed resistive element of the sensor 50 comprises a metal foil 61, 71, 81, 91 printed on a substrate made of electrically insulating material printed on the third surface 14, 14' of the body 11 of the pad 1. Such a metal foil has a first end 61' , 71' , 81' , 91' and a second end 61' ' , 71' ' , 81' ' , 91' ' connected to a first Cl and a second C2 conductor terminal, respectively, of the sensor 50 printed on the substrate made of electrically insulating material printed on the third surface 14, 14' of the body 11 of the pad 1 to electrically connect the printed metal foil 61, 71, 81, 91 to the electronic interrogation and detection means 60, by means of the conductive connecting element 601. The metal foil 61, 71, 81, 91 and the aforesaid first Cl and second C2 conductor terminals are printed to remain rigidly applied to the substrate made of electrically insulating material.

[0070] . In particular, with reference to the embodiment in figure 3, the width La of the printed metal foil 61 is maximum at the second end 61' ' and minimum at the first end 61' ' of the foil. The body of such metal foil 61 has a useful section S for the passage of an electric current applied between the first Cl and second C2 printed conductors which decreases following the reduction of the distance d between the first 12 and second 13 surfaces of the pad 1, i.e., following the increase in wear represented by the arrow Fl .

[0071] . Such a change in resistance can be expressed with the differential equation:(1) where dR is the change in resistance of the foil which is directly proportional to the resistivity p(x) of the metal material forming the foil and the length dx of the resistive element, and inversely proportional to the useful foil section S crossed by the current.

[0072] . For example, the metal foil 61 of the sensor 50 in figure 3 is in the shape of a right triangle with a width La = 8mm and a length Lu = 20mm.

[0073] . In this case, figure 3A shows an increase in the resistance detected by the sensor 50 in figure 3 following a reduction of the width of the sensor 50 caused by the increase in wear of the friction material of the pad 1.

[0074] , With reference to the embodiment in figure 4, the width La of the printed metal foil 71 is maximum at the first 71' and second 71' ' ends and minimum at a median portion of a length Lu of the foil 71 itself, equidistant between the first and second ends. The body of the metal foil 71 has a useful section S for the passage of an electric current applied between the first Cl and second C2 printed conductors which decreases following the reduction of the distance d between the first 12 and second 13 surfaces of the pad 1, i.e., following the increase in wear represented by the arrow Fl .

[0075] . In this case, figure 4A shows an increase in the resistance detected by the sensor in figure 4 following areduction of the width La of the sensor 50 caused by the increase in wear of the pad friction material.

[0076] . With reference to the embodiment in figure 5, the width La of the printed metal foil 81 is maximum at the first 81' and second 81' ' ends and minimum at a median portion of a length Lu of the foil 81, equidistant between the first and second ends. The body of said metal foil 81 comprises a plurality of non-conductive points 82 configured to reduce a useful foil section S for the passage of an electric current applied between the first Cl and second C2 printed conductors. Such a useful section S further decreases following the reduction of the distance d between the first 12 and second 13 surfaces of pad 1, i.e., following the increase in wear.

[0077] . In this respect, figure 5A shows an increase in the resistance detected by the sensor in figure 5 following a reduction of width La of the sensor 50 caused by the increase in wear of the friction material of the pad 1.

[0078] . For example, the metal foils 71, 81 in figures 4 and 5 are U-shaped with a width La=8mm and a length Lu=20mm.

[0079] . With reference to the embodiment in figure 6, the width La of the printed metal foil 91 is maximum at the first 91' and second 91 ' ' ends and also at a median portion of a length Lu of the foil 91, equidistant between the first and second ends. The body of the metal foil 91 has a useful section S for the passage of an electric current applied between the first Cl and second C2printed conductors which decreases following the reduction of the distance d between the first 12 and second 13 surfaces of the padI, i.e., following the increase in wear.

[0080] . In this respect, figure 6A shows an increase in the resistance detected by the sensor in figure 6 following a reduction of a width La of the sensor 50 caused by the increase in wear of the friction material of the pad 1.

[0081] . For example, the metal foil 91 in figure 6 has a rectangular shape with a width La=8mm and a length Lu=20mm.

[0082] , In a further embodiment, shown with reference to figureII, the system 100 of the invention comprises an additional resistive element 150 printed directly on the connecting surface 14, 14' of the body 11 of the pad 1 configured to detect a temperature of the pad 1.

[0083] . With reference to figures 12 and 15, an embodiment of a method 200 of detecting and measuring the wear of the friction material of a pad 1 of a disc brake 10 is described below. Such a method comprises the following steps:

[0084] , - providing 201 a brake disc 2 having a first body 22 adapted to rotate integrally with a wheel of the vehicle;

[0085] . - providing 202 a brake caliper 3, static with respect to the brake disc 2, configured to apply a clamping force to the brake disc during a braking event; the brake caliper has a second body 33 provided with at least one surface 33' facing the first body 22 of the rotating brake disc 2;

[0086] . - providing 203 a pad 1 made of a consumable friction material; such a pad 1 is operatively associated with the brake caliper 3 and has a respective body 11 which includes a first surface 12 and an opposite second surface 13 parallel to the first surface 12 and located at a distance d from the first surface; such a second surface 13 is configured to be in contact with the first body 22 of the brake disc 2 upon clamping the brake caliper 3 on the brake disc 2; the body 11 of the pad 1 includes a third connecting surface 14, 14' between the first 12 and second 13 surfaces .

[0087] . The method 200 comprises a step of directly printing 204 at least one sensor 50 on the third connecting surface 14, 14' of the pad 1, by means of Aerosol Jet Printing methodology or "additive manufacturing" technology or "screen printing" technology, where the at least one sensor 50 comprises at least one resistive element 51, 61, 71, 81, 91.

[0088] . The method 200 further comprises a step of detecting 205, by the at least one sensor 50, the wear of the consumable friction material of the pad 1 upon reducing the distance d between the first 12 and second 13 surfaces of the pad 1, and generating at least one electrical signal SIG representative of the detected wear.

[0089] . Such a step of detecting 205 comprises the further steps of :

[0090] . sending 206, by electronic interrogation and detectionmeans 60 operatively associated with the at least one sensor 50, at least a first electrical signal SIGI for enabling the detection of wear by the at least one sensor 50;

[0091] . - receiving 207, by the electronic interrogation and detection means 60, the at least one electrical response signal SIG generated by the at least one sensor 50.

[0092] . In more detail, the method 200 further comprises a step of directly printing an additional resistive element 150 on the third connecting surface 14, 14' of the pad 1, by means of Aerosol Jet Printing methodology or "additive manufacturing" or "screen printing" technology.

[0093] . The aforesaid step of detecting 205 thus comprises the further steps of :

[0094] . connecting the at least one sensor 50 and said additional resistive element 150 to an electronic measuring circuit 120 in a half-bridge configuration;

[0095] . - measuring the resistance associated with the at least one sensor 50;- calculating the wear of the friction material of the pad 1 from the measured value of said resistance.

[0096] . With reference to figure 12, for example, the electronic measuring circuit 120 in a half-bridge configuration comprises a Wheatstone bridge which includes the resistive sensor 50 and the additional printed resistive element 150 and two additional resistors Ra=Rb which are different from the resistanceof the printed sensor 50. R1 is the resistance of the conductors which connect the sensor 50 and the additional resistive element 150 to the measuring circuit 120. When the resistance value of the printed sensor 50 changes, following wear, the voltage V0 at the output of the bridge changes proportionally.

[0097] . With reference to figures 13 and 16, an embodiment of a method 300 for detecting and measuring the temperature of a pad 1 of a disc brake 10 is described below. Such a method comprises the following steps:

[0098] . - providing 301 a brake disc 2 having a first body 22 adapted to rotate integrally with a wheel of the vehicle;

[0099] . - providing 302 a brake caliper 3, static with respect to such a brake disc 2, configured to apply a clamping force to the brake disc during a braking event; such a brake caliper has a second body 33 provided with at least one surface 33' facing the first body 22 of the rotating brake disc 2;

[0100] . - providing 303 a pad 1 made of a consumable friction material; such a pad 1 is operatively associated with the brake caliper 3 and has a respective body 11 which includes a first surface 12 and an opposite second surface 13 parallel to the first surface 12 and located at a distance d from the first surface; the second surface 13 is configured to be in contact with the first body 22 of the brake disc 2 upon clamping the brake caliper 3 on the brake disc 2, the body 11 of the pad 1 includes a third connecting surface 14, 14' between the first 12 and second 13surfaces .

[0101] . Furthermore, the method 300 comprises a step of printing 304 at least one sensor 50, which comprises at least one resistive element 51, 61, 71, 81, 91 and at least one additional resistive element 150 on the third connecting surface 14, 14' of the pad 1, by means of Aerosol Jet Printing methodology or "additive manufacturing" technology or "screen printing" .

[0102] . Furthermore, the method includes detecting 305, by the at least one additional resistive element 150, the temperature of the pad 1 to generate at least one additional electrical signal SIG' representative of the detected temperature.

[0103] . Such a step of detecting 305 comprises the further steps of :

[0104] . - sending 306, by electronic interrogation and detection means 60 operatively associated with the additional resistive element 150, at least a first electrical signal SIGI' for enabling the temperature detection by the additional resistive element 150;

[0105] . receiving 307, by the electronic interrogation and detection means 60, the at least one additional electrical response signal SIG' generated by the additional resistive element 150.

[0106] . More in particular, step 305 of the method 300 comprises the further steps of:

[0107] . - connecting said additional resistive element 150 to an electronic measuring circuit 130 in a quarter-bridgeconfiguration;

[0108] . measuring the resistance associated with the additional resistive element 150;

[0109] . calculating the temperature of the pad 1 from the measured value of said resistance.

[0110] . With reference to figure 13, for example, the electronic measuring circuit 130 in a quarter-bridge configuration comprises a Wheatstone bridge which includes the additional printed resistive element 150, two additional resistors Ra=Rb and an additional resistor R3 of value equal to the resistance of the element 150. R1 is the resistance of the conductors which connect the additional resistive element 150 to the measuring circuit 130. The sensor 50 is disconnected from the measuring circuit.

[0111] . When the resistance value of the resistive element 150 changes, following changes in the temperature of the pad 1, the voltage at the output of the bridge V0 changes proportionally.

[0112] . With reference to figure 7, a first embodiment of a connection layout (soldered wire option) of the sensor 50 applied to a pad 1 with the electronic interrogation and detection means 60, through the conductive connecting element 601, of the system 100 of the invention, is described below.

[0113] . In particular, two (or more in case of multiple sensors and temperature sensor) areas (or pads) 31 are preliminarily printed on a plate 1' of the pad 1, which was insulated beforehand by means of an insulating layer. In other words, the areas 31 arelocated in a zone not coated with friction material so as to facilitate the positioning of the conductive connecting element 601 and the connection process. The creation of the connection includes a first step of electrical connection between the terminals of the sensor 50 (or sensors 50, if there are more than one) , located on the third connecting surface 14, and the areas 31 located on the plate 1' of the pad, by depositing conductive tracks 34. For example, this is accomplished by extending the process of printing the sensor 50 to create such connections. A second step in the process includes making an electrical soldering between the areas 31 and the conductive connecting element 601, which forms the wiring of the sensor 50. Such a second step is performed using standard processes, such as hot bar soldering or brazing. In order to impart electrical insulation and mechanical / environmental resistance to the connection obtained, both the conductors of the wiring 601 and the areas 31 of the sensor 50 are coated, at the end of the soldering process, with a globe pot 32 of insulating material, e.g., epoxy resin.

[0114] , With reference to figure 8, a second embodiment of a connection layout (printed interconnection option) of the sensor 50 with the electronic interrogation and detection means 60 through the conductive connecting element 601 which forms the wiring of the sensor 50 is described below.

[0115] . In such a variant, the conductors of the wiring 601 are kept in place with a temporary fixing method (e.g., glue ormechanical device) and the sensor 50 is electrically connected thereto by depositing connection tracks 34' using the same printing technology used to manufacture the sensor (i.e., by extending the printing of the sensor terminal (s) over the areas 31 and conductors of the wiring 601) . The next steps of the process are the same as those described with reference to the solution in figure 7, with the dispensing and curing of an encapsulation element (globe pot) 32 to impart electrical and environmental isolation and mechanical robustness. In this embodiment, the process for making the electrical connection is simplified in that there is no need for the double step of electrical connection between the areas 31 located on the plate 1' of the pad 1 and the sensor 50 placed on the third surface 14 of the pad 1, and soldering between such areas 31 and wiring 601. The areas 31 premade on the plate are configured to be electrically insulated therefrom, and the insulation must ensure coverage of the zone below the connection.

[0116] . With reference to figure 9, a third embodiment of a connection layout (direct wiring-sensor connection option) of the sensor 50 with the electronic interrogation and detection means 60 of the system 100 of the invention is described below.

[0117] . In this example, the mechanical component comprises the pad 1 having a body 11 with which a respective appropriately modified plate 111 is associated, comprising a leg 110 having a "C"-shaped section in the connection zone. Such a leg 110, whichdelimits a housing 110' , can be obtained by blanking, bending or different types of machining, based on the thickness of the component and the material used. The surface of such a leg 110 and the surrounding zone, up to the third surface 14 of the pad 1 where the sensor 50 is printed, is then coated with an insulating material to avoid conduction of electricity through parts which do not strictly belong to the circuit-connector system. Afterwards, one or more cables 112, e.g., three cables, needed to ensure the connection to the interrogation and detection means 60, are located inside the housing 110' of the leg 110. Such cables 112, which form the wiring 601 of the sensor 50, can have different conductor sizes and coatings. However, it is required that each cable have an end cable portion 112' lacking an insulating coating so as to provide exposed terminals 113 which protrude from the plane of the plate 111 and are orthogonal to the third surface 14. Such exposed terminals 113 are connected to the sensor 50. By means of a dosing process, a resin (phenolic, epoxy, silicone resin or of other type depending on the stress temperature) is deposited in the housing 110' of the leg 110 thus mechanically blocking the electrical cables 112, finally resulting in cables nearly completely submerged in resin, having only the exposed terminals 113 as the sole uncoated part. Finally, the connection process includes electrically connecting the sensor 50 to the exposed terminals 113 of the cables 112 by depositing conductive tracks 113' with the same printing technology used to manufacturethe sensor 50, i.e., extending the printing of the conductive layer of the sensor (s) over the exposed terminals 113. The process is completed by providing the electrical isolation of the exposed terminals 113 and the conductive tracks 113' by localized deposition of insulating material.

[0118] . A variant of this design involves electrical soldering, such as brazing, to connect the sensor 50 and the exposed terminals 113.

[0119] . With reference to figure 10, a fourth example of making a connection layout (wiring option on the rear plate, connection carried out by conductor printing) of the sensor 50 with the electronic interrogation and detection means of the system 100 of the invention is described below.This variant provides a solution for installing a wiring 122, 601 adapted for high temperatures, e.g., by employing insulation sheaths made of technopolymers or glass-fiber or glass-quartz.The mechanical component comprises the brake pad 1 having a body 11 fixed to a plate 111. The wiring 122, 601 is fixed to a surface Illa of such a plate 111 opposite to the brake pad 1 and held in place by means of fixing elements 123 mechanically constrained to such a surface Illa of the plate 111, e.g., soldered foils. An end portion 124 of the wiring 122, 601 includes a section of the conductors of the wiring 122 exposed on a surface parallel to the third surface 14 of the pad 1 on which the sensor 50 is made. The connection process includes electrically connecting the sensor 50to the exposed surface of the conductors 124 of the wiring 122, 601 by depositing conductive tracks 125 with the same printing technology used to manufacture the sensor (i.e., extending the printing of the conductive layer of the sensor (s) over the connector terminals) . The terminals thus connected are then insulated and protected by a Globe Pot process, so as to impart electrical insulation and mechanical / environmental resistance to the connection.

[0120] . The plate 111 is prepared so that an electrical insulation is present in the zone of the electrical connection between the surface 124 and the zone of the sensor 50.

[0121] . The system to detect operating state conditions associated with a disc brake pad has several advantages and achieves the intended objects.

[0122] . Indeed, printing conductive and insulating materials by means of Aerosol Jet Printing technology provides advantages in terms of the multiplicity of materials to be used, printing accuracy, and adaptability to non-planar surfaces.

[0123] . Furthermore, the two sensors 50, 150 are printed in the same process; therefore, there is no differentiation of parts between a wear sensor and a temperature sensor.

[0124] , The two functions, i.e., the detection of wear and temperature, are achieved using only a 3-wire connection with the ECU.

[0125] . The temperature sensor 150 is positioned on the frictionmaterial of the pad 1, therefore there are no intermediate materials or layers which can affect the measurement by introducing attenuation or filtering. The integration of the sensors does not affect the operation of the pad at all, because wear is sensed by a thin layer of paint, unlike the prior art in which thick materials are worn away by friction during operation, with potential critical side effect of emerging vibration and noise .

[0126] . With some more complex processing, it is possible to create a temperature mapping by adding several sensors 150 on the same pad 1, keeping integration very simple.

[0127] . Furthermore, the advantage in all the cases described above is that sensors can be printed directly on the mechanical structure, allowing direct contact of the sensing part with the substrate to be monitored.

[0128] . Those skilled in the art may make changes and adaptations to the embodiments of the system and method described above or can replace elements with others which are functionally equivalent in order to meet contingent needs without departing from the scope of the following claims. Each of the features described above as belonging to a possible embodiment can be implemented irrespective of the other embodiments described.

Claims

CLAIMS1. A system (100) for detecting operating state conditions associated with a pad (1) of a disc brake (10) of a braking system of a vehicle, the detecting system (100) comprising said disc brake (10) , the disc brake (10) comprising: a brake disc (2) having a first body (22) adapted to rotate integrally with a wheel of the vehicle; a brake caliper (3) , static with respect to said brake disc (2) , configured to apply a clamping force to the brake disc during a braking event, said brake caliper having a second body (33) provided with at least one surface (33' ) facing the first body (22) of the rotating brake disc (2) ; the aforesaid pad (1) made of a consumable friction material, said pad (1) being operatively associated with said brake caliper (3) and having a respective body (11) including a first surface (12) and an opposite second surface (13) parallel to said first surface (12) and placed at a distance (d) from the first surface, said second surface (13) being configured to be in contact with the first body (22) of the brake disc (2) upon clamping the brake caliper (3) on the brake disc (2) , the body (11) of said pad (1) including a third connecting surface (14, 14' ) between said first (12) and second (13) surfaces, said detecting system (100) further comprising: at least one sensor (50) printed directly on said third connecting surface (14; 14' ) of the pad (1) , wherein said atleast one sensor (50) comprises at least one resistive element (51; 61; 71; 81; 91) printed on said third surface (14; 14' ) of the pad (1) by means of Aerosol Jet Printing methodology or "additive manufacturing" technology or "screen printing" technology, said at least one sensor (50) being configured to detect the wear of the consumable friction material of the pad (1) following the reduction of said distance (d) between the first (12) and second (13) surfaces of the pad, and to generate at least one electrical signal (SIG) representative of the detected wear;- electronic interrogation and detection means (60) operatively associated with said at least one sensor (50) , adapted to send at least a first electrical signal (SIGI) for enabling the detection of wear by the at least one sensor (50) and for receiving said at least one electrical response signal (SIG) generated by the at least one sensor (50) .

2. A system (100) for detecting operating state conditions associated with a pad (1) of a disc brake (10) according to claim 1, wherein said third connecting surface (14) is orthogonal to the first (12) and second (13) surfaces of the pad (1) •3. A system (100) for detecting operating state conditions associated with a pad (1) of a disc brake (10) according to claim 1, wherein said third connecting surface (14) comprises atleast one portion (14' ) inclined with respect to both the first (12) and second (13) surfaces of the pad (1) , said at least one sensor (50) being printed directly on said inclined portion (14' ) of the third connecting surface (14) .

4. A system (100) for detecting operating state conditions associated with a pad (1) of a disc brake (10) according to any one of claims 1-3, wherein said at least one resistive element (51; 61; 71; 81; 91) printed on said third surface (14; 14' ) of the pad (1) has a width (La) less than said distance (d) between the first surface (12) and the second surface (13) parallel to the body (11) of the pad (1) , said at least one resistive element (51; 61; 71; 81; 91) having an increasing resistance as said width (La) decreases, caused by the reduction of said distance (d) between the first (12) and second (13) surfaces of the pad ( 1 ) .

5. A system (100) for detecting the operating state conditions associated with a pad (1) of a disc brake (10) according to any one of the preceding claims, wherein said at least one printed resistive element (51) of the sensor (50) comprises a plurality of mutually parallel metal tracks (52) printed on a substrate made of electrically insulating material printed on said third surface (14; 14' ) of the body (11) of the pad (1) , each of said tracks having a first end (52' ) and a second end (52' ' ) connected to a first (Cl) and a second ( C2 ) conductor terminal of the sensor (50) , respectively, printed onsaid substrate made of electrically insulating material printed on the third surface (14; 14' ) of the body (11) of the pad (1) to electrically connect said metal tracks (52) to the electronic interrogation and detection means (60) .

6. A system (100) for detecting operating state conditions associated with a pad (1) of a disc brake (10) according to any one of the preceding claims, wherein said at least one printed resistive element of the sensor (50) comprises a metal foil (61; 71; 81; 91) printed on a substrate made of electrically insulating material printed on said third surface (14; 14' ) of the body (11) of the pad (1) and having a respective first end (61' ; 71' ; 81' ; 91' ) and a second end (61' ' ; 71' ' ; 81' ' ; 91' ' ) connected to a first (Cl) and a second (C2) conductor terminal of the sensor (50) , respectively, printed on the support made of electrically insulating material printed on the third surface (14; 14' ) of the body (11) of the pad (1) to electrically connect said printed metal foil (61; 71; 81; 91) to the electronic interrogation and detection means (60) .

7. A system (100) for detecting operating state conditions associated with a pad (1) of a disc brake (10) according to claim 6, wherein the width (La) of said printed metal foil (61) is maximum at said second end (61'' ) and minimum at said first end (61' ) , the body of said metal foil (61) having a useful foil section (S) for the passage of an applied electric current between said first (Cl) and second (C2) printed conductors,which decreases upon reducing said distance (d) between said first (12) and second (13) surfaces of the pad (1) .

8. A system (100) for detecting operating state conditions associated with a pad (1) of a disc brake (10) according to claim 6, wherein the width (La) of said printed metal foil (71) is maximum at said first (71' ) and second (71' ' ) ends and minimum at a median portion of a length (Lu) of the foil (71) equidistant between said first and second ends, the body of said metal foil (71) having a useful foil section (S) for the passage of an electric current applied between said first (Cl) and second (C2) printed conductors, which decreases upon reducing said distance (d) between the first (12) and second (13) surfaces of the pad (1) .

9. A system (100) for detecting operating state conditions associated with a pad (1) of a disc brake (10) according to claim 6, wherein the width (La) of said printed metal foil (81) is maximum at said first (81' ) and second (81' ' ) ends and minimum at a median portion of a length (Lu) of the foil (81) equidistant between said first and second ends, the body of said metal foil (81) comprising a plurality of non-conductive points (82) configured to reduce a useful foil section (S) for the passage of an applied electric current between said first (Cl) and second (C2) printed conductors.

10. A system (100) for detecting operating state conditions associated with a pad (1) of a disc brake (10) according toclaim 6, wherein the width (La) of said printed metal foil (91) is maximum at said first (91' ) and second (91' ' ) ends and also at a median portion of a length (Lu) of the foil (91) equidistant between said first and second ends, the body of said metal foil (91) having a useful foil section (S) for the passage of an applied electric current between said first (Cl) and second (C2) printed conductors, which decreases upon reducing said distance (d) between the first (12) and second (13) surfaces of the pad (1) .

11. A system (100) for detecting operating state conditions associated with a pad (1) of a disc brake (10) according to any one of the preceding claims, further comprising a wiring (601) of the printed sensor (50) adapted to connect the electronic interrogation and detection means (60) to the sensor 50, said wiring (601) being made at least partially on the body (11) of the brake pad of the disc brake (10) .

12. A system (100) for detecting operating state conditions associated with a pad (1) of a disc brake (10) according to claim 11, further comprising: areas (31) printed on a plate (1' ) of the pad (1) ; conductive tracks (34) , printed by means of Aerosol Jet Printing methodology or "additive manufacturing" or "screen printing" technology, for the connection of the sensor (50) located on the third surface (14) of the pad (1) with said areas(31)said wiring (601) of the sensor (50) being connected to the areas(31) by electrical soldering.

13. A system (100) for detecting operating state conditions associated with a pad (1) of a disc brake (10) according to claim 11, further comprising: areas (31) printed on a plate (1' ) of the pad (1) ; conductive tracks (34' ) printed by means of Aerosol Jet Printing methodology or "additive manufacturing" technology or "screen printing", to directly connect the sensor (50) located on the third surface (14) of the pad (1) to said areas (31) and said wiring (601) of the sensor (50) .

14. A system (100) for detecting operating state conditions associated with a pad (1) of a disc brake (10) according to claim 11, further comprising: a plate (111) associated with the body (11) of the pad (1) , said plate comprising a leg (110) having a "C"-shaped section in the connection zone and adapted to delimit a housing (110' ) ; one or more cables (112) of the wiring (601) located in the housing (110' ) of the leg (110) of the plate (111) to ensure the connection towards the electronic interrogation and detection means (60) , each cable having an end cable portion (112' ) without insulating coating to provide exposed terminals (113) adapted to protrude from the plane of the plate (111) and orthogonal to the third connecting surface (14) of the pad (1) , said housing (110' ) of the leg (110) including a resin tomechanically block said electrical cables (112) ; conductive tracks (113' ) printed on said leg (110) , by means of Aerosol Jet Printing methodology or "additive manufacturing" technology or "screen printing" technology, adapted to electrically connect the printed sensor (50) to the exposed terminals (113) of said cables (112) .

15. A system (100) for detecting operating state conditions associated with a pad (1) of a brake disc (10) according to claim 11, further comprising: a plate (111) associated with the body (11) of the pad (1) , said plate; one or more cables (122) of the wiring (601) fixed to a plate surface (Illa) opposite to the pad (1) and held in place by means of fixing elements (123) mechanically constrained to such a plate surface (Illa) , said one or more cables (122) ensuring the connection towards the electronic interrogation and detection means (60) , an end portion (124) of said cables (122) including a section of the wiring conductors exposed on a surface orthogonal to said plate surface (Illa) and parallel to the third connecting surface (14) of the pad (1) on which the sensor (50) is printed;- conductive tracks (125) printed on the surface orthogonal to said plate surface (Illa) , by means of Aerosol Jet Printing methodology or "additive manufacturing" technology or "screen printing" technology, to electrically connect the printed sensor(50) to said exposed end portion (124) of said cables (122) of the wiring.

16. A system (100) for detecting operating state conditions associated with a pad (1) of a disc brake (10) according to any one of the preceding claims, further comprising an additional resistive element (150) printed directly on said connecting surface (14; 14' ) of the body (11) of the pad (1) to detect a temperature of the pad.

17. A method (200) for detecting and measuring the wear of the friction material of a pad (1) of a disc brake (10) , comprising the steps of: providing (201) a brake disc (2) having a first body (22) adapted to rotate integrally with a wheel of the vehicle; providing (202) a brake caliper (3) , static with respect to said brake disc (2) , configured to apply a clamping force to the brake disc during a braking event, said brake caliper having a second body (33) provided with at least one surface (33' ) facing the first body (22) of the rotating brake disc (2) ; providing (203) a pad (1) made of a consumable friction material, said pad (1) being operatively associated with said brake caliper (3) and having a respective body (11) including a first surface (12) and an opposite second surface (13) parallel to said first surface (12) and located at a distance (d) from the first surface, said second surface (13) being configured to be in contact with the first body (22) of the brake disc (2)upon clamping the brake caliper (3) on the brake disc (2) , the body (11) of said pad (1) including a third connecting surface (14; 14' ) between said first (12) and second (13) surfaces;- directly printing (204) at least one sensor (50) on said third connecting surface (14; 14' ) of the pad (1) , by means of Aerosol Jet Printing methodology or "additive manufacturing" technology or "screen printing" technology, wherein said at least one sensor (50) comprises at least one resistive element (51; 61; 71; 81; 91) ;- detecting (205) , by said at least one sensor (50) , the wear of the consumable friction material of the pad (1) upon reducing said distance (d) between the first (12) and second (13) surfaces of the pad, and generating at least one electrical signal (SIG) representative of the detected wear; said step of detecting (205) comprising the additional steps of:- sending (206) , by electronic interrogation and detection means (60) operatively associated with said at least one sensor (50) , at least a first electrical signal (SIGI) for enabling the detection of wear by the at least one sensor (50) ;- receiving (207) , by the electronic interrogation and detection means (60) , said at least one electrical response signal (SIG) generated by the at least one sensor (50) .

18. A method (200) for detecting and measuring the wear of the friction material of a pad (1) of a disc brake (10) according to claim 17, further comprising a step of printing an additionalresistive element (150) directly on said third connecting surface (14; 14' ) of the pad (1) , by means of Aerosol Jet Printing methodology or "additive manufacturing" technology or "screen printing" technology, said step of detecting (205) comprising the additional steps of:- connecting said at least one sensor (50) and said additional resistive element (150) to an electronic measuring circuit (120) in a half-bridge configuration;- measuring the resistance associated with said at least one sensor ( 50 ) ;- calculating the wear of the friction material of the pad (1) from the measured value of said resistance.

19. A method (300) for detecting and measuring the temperature of a pad (1) of a disc brake (10) , comprising the steps of: providing (301) a brake disc (2) having a first body (22) adapted to rotate integrally with a wheel of the vehicle; providing (302) a brake caliper (3) , static with respect to said brake disc (2) , configured to apply a clamping force to the brake disc during a braking event, said brake caliper having a second body (33) provided with at least one surface (33' ) facing the first body (22) of the rotating brake disc (2) ; providing (303) a pad (1) made of a consumable friction material, said pad (1) being operatively associated with said brake caliper (3) and having a respective body (11) including a first surface (12) and an opposite second surface (13) parallelto said first surface (12) and located at a distance (d) from the first surface, said second surface (13) being configured to be in contact with the first body (22) of the brake disc (2) upon clamping the brake caliper (3) on the brake disc (2) , the body (11) of said pad (1) including a third connecting surface (14; 14' ) between said first (12) and second (13) surfaces;- printing (304) at least one sensor (50) , comprising at least one resistive element (51; 61; 71; 81; 91) and an additional resistive element (150) , directly on said third connecting surface (14; 14' ) of the pad (1) , by means of Aerosol Jet Printing methodology or "additive manufacturing" technology or "screen printing";- detecting (305) , by said additional resistive element (150) , the temperature of the pad (1) to generate at least one additional electrical signal (SIG' ) representative of the detected temperature; said step of detecting (305) comprising the additional steps of:- sending (306) , by electronic interrogation and detection means (60) operatively associated with said additional resistive element (150) , at least a first electrical signal (SIGI' ) for enabling the temperature detection by the additional resistive element ( 150 ) ;- receiving (307) , by the electronic interrogation and detection means (60) , said at least one additional electrical response signal (SIG' ) generated by the additional resistive element(150) .

20. A method (300) for detecting and measuring the temperature of a pad (1) of a disc brake (10) according to claim 19, wherein said step of detecting (305) comprising the additional steps of: - connecting said additional resistive element (150) to an electronic measuring circuit (130) in a quarter-bridge configuration; measuring the resistance associated with said additional resistive element (150) ; - calculating the temperature of the pad (1) from the measured value of said resistance.

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