MONITORING THE TEMPERATURE AND WEAR OF THE BRAKE PADS OF THE MOTOR-VEHICLE'S DISC BRAKES

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5 TEXT OF THE DESCRIPTION

Field of the invention

The present invention relates to motor-vehicles, of the type comprising:

10 - a plurality of disc brakes associated with the wheels of the motorvehicle,

- each disc brake including a disc connected in rotation with the respective wheel, and a brake caliper provided with brake pads cooperating with the disc,

15 - a braking system to control the operation of said disc brakes following the intervention of the driver on a brake pedal or following the intervention of an automatic braking system with which the vehicle is provided, and

- an electronic controller of said braking system,

20 - wherein, moreover, with each brake pad of each disc brake there is associated a sensor configured to send a signal to said electronic controller, which is indicative of the temperature of the brake pad and a signal indicative of wear, in terms of reduction of the thickness, of the brake pad.

25 Prior art

A sensor of the type indicated above, capable of continuously detecting both the temperature and the wear of a brake pad of a disc brake is, for example, described and illustrated in document WO 2020/202102 A1.

Studies and experiments by the Applicant have led to the finding that

30 the use of sensors of the type indicated above can open the way to new and advantageous functions for controlling a motor-vehicle. The present invention intends to respond to these needs.

A motor-vehicle according to the preamble of claim 1 is known from EP 2 057 386 B1. Further solutions are known from WO 2020/099329 A1

35 and US 10 328 802 B2. Object of the invention

Therefore, an object of the present invention is to provide new and advantageous methods of controlling a motor-vehicle on the basis of monitoring the temperature and the wear of the brake pads of the disc brakes with which the motor-vehicle is provided.

Summary of the invention

With a view to achieving this object, the invention relates to a motorvehicle having the characteristics that are indicated in claim 1 and preferably also the additional characteristics that are indicated in the dependent claims 2-4.

The invention also relates to a method having the characteristics that are indicated in the attached claim 5, and preferably also having the additional characteristics that are indicated in the dependent claims 6-8.

Detailed description of the invention

The characteristics and advantages of the invention will become apparent from the description that follows with reference to the attached drawings, provided purely by way of limiting example, wherein:

- Figure 1 is a diagram of a braking system of a motor-vehicle, to which the control system of the present invention is applied,

- Figure 2 is a schematic cross-sectional view of an example of a disc brake that can be used in the system according to the invention, and

- Figures 3, 4 are Tables showing the different operating modes which can be implemented with the system according to the invention.

In Figure 1 , the references R1 , R2, indicate the two front wheels and the two rear wheels, respectively, of a motor-vehicle, each of which is associated with a disc brake, indicated by F1 , F2, F3, F4, respectively. Each of the disc brakes F1 -F4 can be made according to any known technique and each comprises a disc D rigidly connected to the wheel hub, so as to be able to rotate with the wheel, and a brake caliper C carried by the motorvehicle structure (not shown) and configured for engaging disc D to slow down its rotation.

Figure 2 shows - by way of example - a schematic and partial cross- sectional view of a disc brake, including a disc D (of which only the peripheral portion is shown), and a caliper C including a caliper body C1 of a floating type, on which a brake pad BP1 suitable for engaging a face of the disc D is rigidly connected. The opposite face of the disc D is designed to be engaged by a second brake pad BP2 carried by a piston P of the fluid actuator of the brake caliper. The piston P is slidably mounted within a chamber CH defined by the body C1 of the brake caliper. The chamber CH is designed to be supplied with pressurized fluid so as to push the piston P to the left (with reference to the drawing) so as to press the pad BP2 against one face of the disc D. At the same time, the supply of pressurized fluid inside the chamber CH also causes a shift towards the right (with reference to the drawing) of the entire body C1 of the brake caliper, so that the brake pad BP1 is pressed against the left side (with reference to the drawing) of the brake disc D.

Of course, the present description is provided here purely by way of example, and is limited to the essential components of the brake, the construction details being of any known type, according to the general knowledge of those skilled in the art. In particular, the configuration of the brake caliper may be of any known type, the case of a floating caliper being shown here purely by way of non-limiting example.

Still according to the prior art, the motor-vehicle is provided with a braking device 1 (Figure 1 ) operated by a brake pedal 2 and hydraulically connected to a pressure modulator assembly 3, which controls the supply of the pressurized fluid to the fluid actuators of the brake calipers C, each fluid actuator being defined by the chamber CH and the piston P sliding within it.

Still according to the prior art, the braking system comprises an electronic controller E connected to the modulator 3 for controlling the operation of the system of the invention.

According to the invention, a sensor is associated with at least one of the brake pads BP1 , BP2 of at least some of the disc brakes (Figure 2 shows the example of two sensors S1 , S2 associated with the two brake pads) of any known type, configured for continuously detecting the temperature and wear, in terms of size and thickness, of the respective brake pad. Again by way of non-limiting example, Figure 1 shows the case wherein all disc brakes F1 -F4 are equipped with sensors, on one or both brake calipers (the dashed lines indicate the connection of the sensors S1 , S2, associated with each disc brake with the electronic controller E). Of course it could be envisaged that the sensors would be associated with one or both brake pads of only some of the disc brakes. It could also be envisaged that only one sensor is associated with one of the disc brakes of the front wheels, and only one sensor associated with only one of the disc brakes of the rear wheels. In the following description, reference is made, purely by way of non-limiting example, to the case wherein each of the disc brakes F1 -F4 is provided with at least one sensor associated with a brake pad.

According to the present invention, depending on the signals provided by the sensors S1 , S2 of the various disc brakes of the motorvehicle to the electronic controller E, this electronic controller is configured to implement a series of different operating modes which are set out below.

According to a first operating mode, the electronic controller E is configured in such a way that:

- when the sensors S1 , S2 of the wear and temperature of the brake pads BP1 , BP2 of the disc brakes F1 - F4 detect wear of the brake pads - in terms of thickness reduction - of a single disc brake that exceeds the wear of the brake pads of the other disc brakes of the motor-vehicle by a value AW greater than a predetermined threshold AWo (see the first row of the Table in Figure 3), or

- when the aforesaid sensors S1 , S2 detect a temperature of the brake pads of a single disc brake that exceeds the temperature of the brake pads of the other disc brakes of the motor-vehicle by a value AT greater than a threshold ATo, with the braking system being inactive, the aforesaid condition is interpreted as an indication of a blocked disc brake, and the electronic controller E performs the following operations:

- the controller activates an operating mode, wherein, during braking, a braking effect obtained by means of a regenerative braking system with which the vehicle is equipped is exploited to the maximum extent,

- the controller disables an air conditioning system of the vehicle, to reduce energy consumption, - the controller prevents the vehicle speed W from exceeding a predetermined maximum limit WLIM to maintain a safe condition even with inefficient disc brakes.

As indicated, the aforesaid operating mode is schematized in the first row of the Table in Figure 3.

According to a further operating mode provided in the present invention, the electronic controller E is configured to also perform the following operation (see the second row of the Table on page 3):

- when the sensors S1 , S2 of the wear and temperature of the brake pads BP1 , BP2 of the disc brakes F1 - F4 detect wear W (understood as a decrease in thickness) of the brake pads of at least one of the disc brakes of the motor-vehicle, which is lower than a predetermined threshold value Wo, where this threshold value is calculated as a function of the kilometers traveled by the motor-vehicle and as a function of the time elapsed since the last replacement of the brake pads, this condition is interpreted as an index of aging and/or loss of efficiency and/or risk of detachment of the brake pads due to prolonged inactivity, and the electronic controller E performs the following operations:

- the controller disables a regenerative braking system with which the vehicle is provided, to facilitate running-in of the brake pads, and

- the controller generates an alarm signal for the driver and/or signals the need to stop the vehicle and/or the need to take the vehicle to the workshop to replace the brake pads.

According to a further operating mode envisaged in the present invention, which is schematized in the third row of the Table of Figure 3, the electronic controller E is configured to calculate the total length of time wherein the sensors S1 , S2 detect, during braking, exceeding of a maximum threshold temperature To of a brake pad of one of the disc brakes of the motor-vehicle, in such a way that:

- when, during braking, the duration t(T>T0) wherein the temperature is above said maximum threshold temperature, exceeds a predetermined length of time (to), this condition is interpreted as due to damage in one or more brake discs and one or more brake pads following a misuse of the braking system, and said electronic controller E generates an alarm signal for the driver and/or indicates the need to stop the vehicle and/or the need to take the vehicle to the workshop.

Preferably, the electronic controller E is further configured to perform one or more of the following operations: a) with reference to the last row of the Table of Figure s, the electronic controller E detects, during braking, the variation over time of the temperature signaled by the sensors S1 , S2 for the brake pads BP1 , BP2 associated with the different axles of the vehicle, and estimating the mass of the vehicle and the distribution of the load on the vehicle axles, as a function of said detected variation of the temperature and on the basis of some information on the longitudinal acceleration of the vehicle, the information being transmitted to said electronic controller E by an acceleration sensor (not illustrated), and, when a load on an axle of the vehicle that exceeds a predetermined threshold is detected, or if a difference between the loads on the vehicle axles that exceeds a predetermined threshold is detected, the electronic controller E prevents the vehicle speed from exceeding a predetermined maximum limit (WLIM), to maintain a safety condition, b) the electronic controller E is also configured to detect a condition wherein the aforesaid sensors S1 , S2 signal, for at least one of the disc brakes F1 -F4, the presence of a non-original brake pad (i.e. a brake pad of a different type than that envisaged in the original equipment of the motorvehicle by the motor-vehicle manufacturer), the sensors S1 , S2 being configured to detect a code associated with the original brake pads and prevent, when the presence of a non-original brake pad is detected, the vehicle speed exceeds a predetermined maximum limit WLIM to ensure a safe condition; c) with reference to the second row of the Table of Figure 4, the electronic controller E is configured to detect a condition wherein, during braking, the temperature T of a brake pad of at least one of the disc brakes of the motor-vehicle remains below a predetermined threshold value TMIN, this condition being interpreted as an indication of a failure of the braking system or hydraulic losses in the braking system, so that the electronic controller E, in this condition, generates an alarm signal for the driver and/or a notification of the need to stop the vehicle and/or the need to take the vehicle to the workshop; d) with reference to the third row of the Table of Figure 4, the electronic controller E is also configured to detect the variation in wear W of the brake pads BP1 , BP2 of the disc brakes F1 -F4 of the motor-vehicle over time, to estimate, on the basis of this detected variation, the kilometers of residual life of the brake pads BP1 , BP2, to evaluate the driving style with which the motor-vehicle is driven, according to information received from the electronic controller E on parameters indicative of the driving style, such as, for example, frequency and intensity of braking, longitudinal and transversal accelerations of the motor-vehicle, engine rpm, the electronic controller being able to limit the maximum speed of the vehicle near the end of the estimated life of the brake pads and/or if the driving style detected indicates a condition of lack of safety; e) with reference to the last row of the Table of Figure 4, the electronic controller E is also configured to detect, by means of the sensors S1 , S2, when there is wear AW higher than a threshold value Wo, or a temperature T higher than a threshold value To on the brake pads of the disc brakes of the same axle of the vehicle, during braking; in this case, the electronic controller interprets this condition as an indication of an overload on one axle of the vehicle during braking, and consequently controls the braking system to vary the ratio between the braking actions on the various axles of the vehicle. Thanks to the aforesaid characteristics, the control system according to the invention drastically increases the safety level of the motorvehicle, without at the same time involving a more complex or more expensive structure. The invention lends itself to being used both on conventional motor-vehicles, with internal combustion engines, as well as on electric or hybrid vehicles or even on self-driving motor-vehicles. Likewise, the invention is applicable both to braking systems of the conventional type, with hydraulically actuated disc brakes, and also to braking systems using electro-actuated brake calipers.

Of course, without prejudice to the principle of the invention, the details of construction and the embodiments may vary widely with respect to those described and illustrated purely by way of example, without departing from the scope of the present invention.