CONTROL METHOD FOR REGENERATIVE BRAKING WITH ANTI-LOCK SYSTEM OF A ROAD VEHICLE WITH INDEPENDENT ELECTRIC MOTORS AND RELATED ROAD VEHICLE

Description

“ METHOD AGAINST LL GENERATE VACONSYSTEM OPERFRAKES CC TO GG ANTIBLO ROAD VEHICLE TT RICI INDEPENDENCE RELATING TO ROAD VEHICLE ” * % % IF TT HEAR LL TECHNICAL The present invention relates to a method of check for regenerative braking at least partially simultaneous braking with antilock system of a road vehicle with independent electric motors agents on at least two (especially out of four) wheels; the present invention further relates to a related road vehicle configured to perform such a method. THE FRONT RTE S onotimetodiperilrec upero , mediantelacosi dde tta regenerative braking, of electrical energy in vehicles equipped with electric propulsion provided by high-voltage batteries voltage. And in fact it is known that a part of the braking action, normally allocated to the effect of friction between a pad placed in contact with a disc by means of the action of a hydraulic force generated by the pilot (via pressure on a brake pedal) and assisted with various solutions techniques (brake boosters, hydraulic pumps), both supported by an electric braking applied by an electric motor placed in mechanical connection with the wheels (according to different known and not further detailed architectural schemes in the following). Generally, the energy recovered in this way from the on the said electric motor way it is reintroduced inside of the high voltage battery, causing the effect of increase its state of charge (SOC) for future restitution in electric propulsion situations. According to the known art solutions, the recovery of electricity is severely limited, especially in high-performance vehicles, so as not to exceed a default deceleration value (even if the vehicle was equipped with a propulsion system from absorption potential higher than the said wvalue default). Furthermore, 1the prior art solutions provide for a fixed distribution between front and rear axle, the which is not always optimal, limiting the energy recovery potential and therefore performance of the road vehicle. In addition, according to known type architectures, the energy recovery is sized to be fixed under standard braking conditions, the brakes are disabled under ABS braking conditions, providing, in these cases, to modulate the braking force exclusively through 11 l hydraulic / mechanical circuit that manages the brakes conventional. However, in highly performance vehicles the energy recoverable may be overabundant due to the important accelerations in play and can determine a factor of absolute importance also in performance. In in particular, the “emergency” braking, that is, those in when the ABS comes into play, they are even more frequent in high-performance vehicles racing on the track. And therefore the need for an improved system of electricity management, 1which becomes a important resource not only in terms of distribution of electric torque to the motors, but also in terms of electrical energy regeneration during braking. In fact, having a greater quantity of available energy, allows you to improve your performance on the track, for example and for example allowing the delivery of greater torque in acceleration for 11 completion of a race. DESCRIPTION OF THE INVENTION The object of the present invention is to provide a method regenerative braking control of a road vehicle with independent electric motors acting on at least two, in particular four, wheel drive and a related vehicle road, which are free from the above inconveniences described, are easy and economical to implement, and particular allow to maximize performance while driving on a track without making the vehicle unstable road. According to the present invention, a method is provided regenerative braking control of a road vehicle with independent electric motors acting on at least two, in particular four, wheel drive and a related vehicle road, according to the claims in d e p e nd e nts who follow and, preferably, in a any of the claims directly or indirectly arising from indirectly from independent claims. The claims describe embodiments preferred embodiments of the present invention forming part integral to this description. BRIEF DESCRIPTION OF THE SIGNS The present invention will now be described with refer to the drawings nn and ss i, which are an example in the illustration non-limiting implementation, in which: — Figure 1 is a schematic and plan view of a road vehicle in accordance with the present invention and equipped with four separate and independent motors; — Figure 2 is a schematic diagram of a non restrictive form of implementation of the method in accordance with the present invention; — figure 3 shows a diagram of a braking of the vehicle in figure 1 in which the ABS is activated in combination with regenerative braking. FORMEDIA TTU PREFERRED ACTION OF THE INVENTION In figure 1, the number 1 is indicated in its complex road vehicle, in particular a motor vehicle, provided with a front 2nd ss road and a rear axle 3. The same reference numbers and letters in the figures they identify the same elements or components with the same function. In the context of this description 11 term “second” component does not imply the presence of a “first” component. These terms are in fact used as labels to improve clarity and are not to be construed as limiting way. The elements and features illustrated in the various preferred embodiments, including drawings, can be combined with each other without exiting from the scope of protection of the present application as described following. It is specified that in the following description, expressions such as “above”, “below”, “ previously ” , “ posteriorly ” are also useful with reference to conditions of normal advancement of the vehicle or 1 roadway along the normal direction D of advancement . As illustrated in the non-limiting form of implementation of Figure 1, it is also possible to define: - a longitudinal ss and X , solidaritywithvehicle 1 and arranged , unused , outside the abnormal law direction D of advance of vehicle 1; - a transverse ss and Y , solidarityvehicle 1 and arranged , unused , or zz ontaleeorthogonal to the X axis ; and - a vertical ss and Z , solidarityvehicle 1 arranged , in use, vertical and orthogonal to the X, Y axes. The vehicle 1 road includes four wheels 4, 5 divided into pairs between 1anterior 2nd axis and 1st 3rd axle rear. In particular, of the four wheels 4, 5, at least two, specifically all four, are driven wheels. In other words, vehicle 1 comprises two wheels 4 front ( engines ) , front end of the front 2 axles , and two rear 5 wheels (also driven), part of the rear 3 axle. In particular, 11 vehicle 1 can be traction front , or vv eroconsolewheel 4 front motors , a rear wheel drive , or vve 5 rear sunroof engines , integral drive , wheel accounts 4 , engines , such as 1 ll unlimitedshaped ustratone implementation of the attached figures. The ve ic or lo <comprende inoltre un sistema 6 di propulsion, which in turn includes two or four electric 7 engines (according to wheel number 4, 5 engines and to the typology of direct or indirect actuation - through differential), <ciascuno dei quali è connesso ad una respective wheel 4, 5 by an appropriate drive system which allows the torque exerted by each wheel to be varied 4, 5 independently of the others and in an adjustable manner according to default logic. To that end, according to some non-limiting forms of implementation, there are expectations motors 7 ele tt receiverwheel , whilesecondary unlimited use , is present active differential (known and therefore not further detailed below) that allows you to issue (and receive) diversify pairs to wheels of the same 3 or 4 axle. In particular, according to a preferred but not limited cheese tt uation , each wheel 4 , 5 is operable rotation from a respective essence 7 essence motor connected. The 7 electric motors are mechanically coupled to the wheels 4, 5 and are configured to deliver or receive torque drive train with wheels 4, 5 and 6, depending on the function driving or generating force which respectively exert in acceleration and deceleration / braking. Each wheel 4 or 5 is mechanically connected to a chassis of the road vehicle 1 by means of a suspension 10 (partially illustrated in Figure 1), which is equipped with an electronically controlled shock absorber 11, or equipped with an electric actuator that allows vary (i.e. increase or decrease) the damping of the electronically controlled shock absorber 11. By way of example, the electric actuator of each shock absorber 11 electronically controlled may include one or more solenoid valves that modulate the size of holes oil flow inside the shock absorber 11 a electronic control, or it may include a fluid magneto-rheological which changes its physical properties in function of an applied magnetic field. In addition, vehicle 1 includes a circuitry 8 control electronics, which includes one or more units 9 against the calculation (“ECU”) which, among other things, rule 1l the behavior of the road vehicle both in straight, both when travelling around a curve intervening, as better described below, on the couple generated by 7 electric motors thanks to 4, 5 wheels deceleration motors. Physically, the circuitry 8 of control can be composed of a single device or from multiple devices that are separate and communicating through the CAN network of the road vehicle 1. Advantageously, the 8 electronic circuitry of control is configured to estimate, for each wheel 4, 5 drive, independently of the other wheels 4, 5 drive, a respective G-factor of grip on the ground travelled by the road vehicle 1. In particular, the grip factor G on the ground is calculated according to known methods and therefore not further detailed below. This G factor of adhesion could be estimated, whether detected according to known techniques, such as described in the application for Italian patent 102021000020948 filed by the same Applicant. Furthermore, the 8 electronic circuitry is configured to defineoridetect , perwheel 4 , 5 motor , regardless of the other wheel 4 , 5 engines , a respective load Fz vertical agent on it. You particularly, 11 load Fz is also defined or detected by means of noted techniques and ©therefore not further detailed below (ie measuring the load, ie force, Fz with special sensors or estimating it through you vehicle action mode 1 road ) , as an example described in Italian patent application filed by the Applicant herself. The electronic 8 circuitry is also configured for process , perwheel 4 , 5 drive , one MRT value of a maximum braking capacity (regenerative, i.e. maximum regenerative torque) as a function of at least the respective adhesion factor G and the respective vertical load Fz. In particular, the maximum braking capacity is determined according to known methods and therefore not further described in the following. For example, the maximum braking capacity can be defined in terms of torque. P referiblybutnonlimitatively, the vehicle 1 It also includes a 12 DD data collection system, the which is connected to the control circuitry 8 and is configured to detect a plurality of DD data on the of vehicular dynamics. In particular, the DD data detected by the 12 detection system include at least are at least the speed Vx (longitudinal) of vehicle 1, 1which is preferably but not limited to detected by means of speed sensors located at the wheels 4, 5; the driver's DR requests, e.g. how much and how an accelerator or brake pedal is pressed or turned the steering wheel; and the longitudinal accelerations Ax and Ay transversal, for example detected by one or more units of inertial measurements (which are known in themselves and therefore no longer (detailed) of road vehicle 1. The road vehicle 1 also includes a system 13 of braking, comprising at least one element 1 4 braking system that can be activated by the driver to request a braking, especially a 15 brake pedal. Advantageously, the braking system 13 comprises also a 18 hydraulic unit, and 19 mechanical brakes there, controlled unit 1 8 hydraulics . Specifically, 11 braking system 14 is connected to the control circuit 8 and is configured to be by it commanded. Beneficially, 1the control 8 circuitry is further configured to command the braking system 13, following a braking request (particularly from emergency , or vv erode a pedal brake 1 5 brake is crushed suddenly and forcefully) by the DR driver through 1 l element 1 4 braking , unmodeled drive, the 18 hydraulic unit to exert a mBT torque reverse brakes 4 , 5 engine Indeed , circuit 8 control is also configured to command the braking system 13, in added to the respective braking mBT torque, to drive in generative electric braking, delivering a respective with BT brake pads , each wheel 4 , 5 engines respect electric motor 7 , respectively function value of maximum braking capacity MRT and in particular of the mBT pair, cosl to denature electrical energy of recovery. In other words, for example, when the driver DR press brake pedal 15, control circuitry 8, in particular unit 9 opposite , unbraked command each of the 7 electric motors with a respective torque eBT electric braking (i.e. counter-motor), thanks to the which can be generated using 7 electric motors as generators, recovered electricity, i.e. recovered by converting the kinetic energy of the wheels 4, 5 engines in electric energy during braking. Furthermore, the control circuitry 8 is configured to modulate, at least for each 4, 5 drive wheel (so in the case illustrated for all four wheels 4, 5), the mBT braking torque and / or eBT braking torque so that the sum of the hydraulic braking mBT torque and the torque eBT electric braking is, instant by instant, equal or lower than the respective maximum capacity MRT value braking (for the respective wheel). I n particular, the hydraulic unit 1 8 includes a ABS anti-lock braking system (of known type and therefore not further detailed below), which, when activated, it determines the modulation of the first mBT pair braking. In other words, in case of braking emergency, such as the kind that are known to activate the ABS anti-lock braking system, the ABS anti-lock braking system controls the mechanical brakes 19 with a triangular modulation of known type, which loosens the braking torque mBT hydraulic as soon as dJuesta reaches 11 wMRT value of maximum braking capacity (for the respective wheel) so as to prevent it from locking, thus allowing wheel 4, 5 to continue rotating without slipping areas too much. Finally, the electronic control circuitry 8 is configured to store the aforementioned electrical energy of recovery generated by the regenerative braking of each wheel 4, 5 in a 1 6 system ( common between wheels 4, 5 ) of storage of vehicular electrical energy, in particular in a vehicular battery pack 17. In other words, 1'energy generated under braking thanks to the 7 electric motors converges in a main battery pack 17 of the road vehicle 1, for a subsequent use during acceleration, so as to increase performance, for example when exiting from a curve on a track. In accordance with a further aspect of this invention, a control method is provided for a regenerative braking, particularly when using a A BS system, road vehicle and tt o by a DR driver. Advantageously but not limitationally, the vehicle 1 road, especially the control circuitry 8, is configured / scheduled to perform the following method described. The method includes the stages of: - estimate , through circuit 8 opposite , in detail through at least one of the 9 control units or calculation , percussion wheel 4 , 5 engine , regardless from the other wheel 4 , 5 engines , 1 respective G di adherence to soil traveled by vehicle 1 roadway; - defineoridetect , throughcircuitry 8 of control, particularly through at least one of the units 9 against the calculator , wheelchair , 4 , 5 engine , regardless of the otherwheel 4 , 5 engines , the respective load Fz vertical agent on it; - process , through circuit 8 control , in particular through at least one of the 9 control units calculator , wheel 4 , 5 engine , MRT value of the maximum braking capacity in function of at least the respective adhesion factor G and respective load Fz vertical; - command , through circuitry 8 opposite , in particular through at least one of the 9 control units calculus , system 1 3 braking , following emergency braking request by the driver DR (for example by brake pedal 1 5) , unmodulated operate the 18 hydraulic unit to exert the mBT torque brakes at least on each wheel 4, 5 drive (in detail on all four wheels 4, 5); - command 1 system 1 3 braking, unmodulated actuate 1in generative electric braking, applying the respective braking eBT torque, in addition to the respective co pp iam BT brake , each wheel 4 , 5 engines respect to electrical electric motor 7 , at least the respective wvalue of maximum braking capacity MRT and in detail of the first mBT pair, so as to generate energy recovery electric; - modular, at least for each 4, 5 drive wheel, the first braking mBT pair and / or the second eBT pair braking so that the sum between the first pair mBT braking and the second eBT couple is, moment by moment, equal to or less than the respective maximum capacity MRT value braking; - store recovered electrical energy generated by regenerative braking of each wheel 4, 5 in storage system 17. In particular, the anti-lock braking system ABS, including in the hydraulic unit 18, by activating, determines mBT braking torque modulation. More specifically, therefore, at least in some intervals of time during an emergency braking, 11 system ABS anti-lock braking system determines a variation in the mBT torque hydraulic braking while the eBT electric braking torque (and the MRT value of maximum braking capacity) remain constants. Preferably, during the modularization phase, for each wheel 4, 5 drive, eBT torque is controlled so as to be in agreement with the respective value of the maximum braking capacity MRT of the 4,5 wheel drive. In particular, therefore, the braking eBT torque electric is controlled so as to correspond, in predefined conditions, at a regenerative percentage default of the respective value of the maximum capacity MRT braking. More specifically, the default conditions include at least the features of maximum braking capacity MRTs constant and / or decreasing over time. According to some preferred but not limiting forms of a tt uation , therefore , as the stratone of the cheese shown in Figure 3 , during the least part , in particle strengthening othality , of the vazionedel ABS antilock system, ie during modulation (triangular) of the mBT pair, the eBT pair is commanded at a respective constant bearing BV value for each wheel 4 , 5 drive . For example , ifthe value of BT remain constant at the values ​​BV', BV' bearing in matching of the intervals I', I'' during braking of emergence that generates the graphs illustrated in Figure 3 In particular, 11 wvalue BV, BV ' , BV ' ' ' bearing corresponds to a predefined percentage of the maximum MRT braking capacity of the respective wheel 4, 5 engine. The extremely unlimited range , the value of BV , BV ' , BV'' bearing corresponds to at least 10%, in particular at least 20%, preferably at least 30% of the maximum MRT brake capacitor of the wheel 4 , 5 engine According to further forms of non-limiting implementation and not illustrated, the method includes the further stages of: - detect the plurality of DD data on the dynamics vehicles; and - calibrate the respective load BV value of the eBT torque according to DD data on vehicle dynamics. P referably handles them mitotically , during the phase remote control system 1 3 differential braking , at least marked 4 ' , 5 " right wheel 4 ' ' , 5 ' ' left wheel front axle 2 or rear 3 are commanded in such a way independent of them , d distributing percentagetradi and ss and the braking in a differentiated manner. In other words, the eBT electric braking torque controlled at wheel 4', 5 / right differs from the eBT electric brake pair command ll written 4 ' ' , 5 ' ' left C onsistently , d denotes the electrical energy generated by wheel 4', 5 / right compared to that generated by the wheel 4'', left. Neglecting this difference, 1energy electricity is preferably stored in the system 16 of accrual to be assignable to any of the engines 7 electrical. Alternatively or in addition, during 1the phase of control the regeneration system , wheel 4 ( or 4 ' e 477) of the front axle 2 and the wheels 5 (ie 5' and 5'') of the rear 3 axle are commanded in such a way independent tetralore , distributing the brake unmode differenced, for example percentageally, between 1 axis anterior and 1axle 3 rear. In other words, the couple eBT electric brakes driven to the front 4 wheels differs from the commanded eBT electric braking torque to the rear 5 Consistently , energy risks electric generated by the 4 front wheels compared to the one generated by the 5 rear wheels. Regardless of this difference, electricity is ©preferably stored in the storage system 16 to be delivered to any of the 7 electric motors. Advantageously but not limitingly, the respective eBT braking torque delivered to at least one wheel 4, 5 (in particularatu tt and wheels 4, 5, or at least on dd iviseper axle torque 2, 3) is dynamically variable over time (during braking, or while the driver requests 1 la braking via the pedal). In particular, the electric braking eBT copy and variable refresh rates above 3 Hz, in especially above 5 Hz; more specifically with refresh rates of 10 Hz or higher. Advantageously but not limitingly, therefore, 1la respective eBT braking torque delivered by a wheel 5 (i.e. 5 7 , 5 ' 7 ), in particular from both wheels 5 , 5 , 5 ' 7 " , of the rear axle 3 remains constant or preferably increases as time passes during braking, gradually that the speed Vx (longitudinal) of road vehicle 1 is reduces. Preferably but non-limitatively, the respective eBT braking torque delivered by wheel 4 (i.e. 4', 4'7), in particular on both wheels 4, 4', 4'', of the axle 2 front remains constant or preferably decreases to time passes during braking, as the speed Vx of vehicle 1 road is reduced. As illustrated in the attached figures, the method thus includes a phase of commanding 11 system 14 of brakes in brake mode, adausiliode ll braked regenerative supplied by the 7 electric motors, and therefore in added to the respective braking eBT couple, 1-unit 18 hydraulics to exert the braking mBT torque on each wheel 4 , 5 , at least partially simultaneously to the braking torque. P referably handling them metaphorically , ecome illustrated in Figure 3, the eBT braking torque comes and connected (always) simultaneously to the pair m BT brake. Some unlimited layers occur , aldi above a certain longitudinal speed Vx and in the presence of a certain request for (emergency) braking by of the driver, the eBT braking torque is exerted in delay with respect to the braking mBT torque, which comes into play action first. In particular, the mBT braking torque delivered from the hydraulic unit 18 is independent for each wheel 4, 5 respectively of front axle 2 or axle 3 rear, depending on its rotation speed with respect to the longitudinal speed Vx of vehicle 1 road. For example, the speed of each wheel is detected by means of a respective tone wheel. Advantageously but not limitingly, the circuitry 8 control is configured to perform the method described in this description. In accordance with what was previously said, therefore, the braking potential of each individual wheel 4, 5 is a function of the adhesion factor G, of the applied vertical load Fz on wheel 4, 5 (or on the respective tire) as well as of the possible presence of lateral commitment required by the tire itself (the possible acceleration Ay). It follows that under dynamic conditions of load transfer, such as braking on a straight line (where there is a load transfer towards the front axle 2) or braking on a curve (where you have a brake again load transfer to front axle 2, but with lateral force demand on the tires of the 4 wheels, 5, to limit the braking capacity itself), the _20_ 8 control circuitry commands the 7 electric motors and the hydraulic unit 18 dynamically adjusting the share, that is, the percentage of hydraulic braking compared to the electric braking, i.e. of the mBT torque with respect to the eBT pair, based on the specific conditions of each individual wheel 4 , 5 . Therefore, according to the above forms of implementation described or a combination thereof, having available an estimator (of known type) of the overall capacity braking of each wheel 4, 5 is therefore possible (in the absence (ABS control) to better distribute the action braking (calibrating / modulating the eBT and mBT torques) and maximizing energy recovery (if you have a fixed braking eBT torque distribution too high for a single wheel 4, 5, its reduction or elimination should bb hero sse ree ff e tt uation the entire ss ale 2, 3 braking, losing the possible contribution of the other wheel of the innkeeper 2, 3). In the non-limiting form of implementation of the figure 2, and a portion of the schematically illustrated control circuitry 8, comprising two control units 9 control or calculation. Following the flow of information (indicated by the arrows), the first control unit 9 receives input a BC signal relating to the conditions (model, size and status) of the battery pack 17 (and its _21_ limits) and an EMC signal, relating to the conditions (model, size and status) of the 7 electric motors (and their 1 limits). At the entrance signal light, unit 9 of control processes, for each wheel 4, 5 (i.e. four values) the maximum electric MRT braking capacity, which It is preferably expressed as maximum braking torque deliverable by 7 electric motors taking into account also the battery pack 17. The four maximum braking capacity MRT values are given as input to the second control unit 9 (which physically can also coincide with the first), together to the dynamic DD data of the road vehicle 1 and to a signal PFS related to the 1 limitations imposed by security functional of the road vehicle 1 (the so-called Automotive functional safety or FuSa, defined for example by ISO 2 6 2 6 2 ). In addition to these signals, it is considered furthermore the G factor of adhesion calculated or estimated as described above and as is known. In light of these signals in input, the control unit 9 processes the distribution of the regenerative brakes on wheels 4, 5, or vve rola combination of the respective eBT pairs and the second ones mBT couples. For example, in general, in the case where there is only one electric axle, the percentage distribution of torque electric braking is independently adjustable between wheels _22_ 4 ' , 5 ' right wheel 4 ' ' ' , 5 ' 7 ' left (front) rear whether it is axle 6 or 7). This distribution diversified braking torque can be delivered either via a single 7 electric motor connected to a active differential, in turn connected to the wheels, or through two electric motors , one each wheel 4 , 5 dinoste ss or axle. For example , in addition , in case both electrical 7 , percentage distribution electric braking torque is adjustable independently between wheel 4 ' , 5 ' right wheel 4 ' ' ' , 5 ' ' left (anterior posterior to either axle 6 or 7) of both axles 6, 7. This diversified braking torque distribution pud be powered either by a single electric 7 engine for each power axle connected to a differential active , low voltage attached to the wheels , or retramite four respective 7 electric motors, one for each wheel 4, 5. In this way, it is possible to independently adjust both the relative percentage distribution between wheels of one same axle, both between the two different axles 6, 7, so optimize / maximize the recovery of electrical energy in different situations (straight lines, curves, ascent, descent, sloped road or a combination of these). Therefore, it is also possible to experimentally define different distribution strategies of the eBT pair and the mBT couple, depending on the aforementioned factors taken into consideration. According to some non-limiting and non-binding forms of implementation i ll u strate, 1le wvalli in the modulation of the mBT pair mechanical / hydraulic braking by the system anti-lock braking system ABS, preferably correspond to the value BV carrier of the electric braking torque eBT. In other words, the electric braking eBT torque is modulated in so that the modulation valleys of the mBT pair correspond to a hydraulic pressure equal to (or close to) to zero. Alternatively or in addition, the eBT braking torque electrical is modulated by the control circuitry 8 in so that the sum of the electric braking torque and the mechanical / hydraulic braking mBT torque matches substantially (less than a margin of safety, for example) empirical example), instant ©by instant, at the maximum MRT braking capacity of each driving wheel 4, 5 (in detail of all four drive wheels). Although the invention described above is particularly reference to a very specific example of implementation, it it is not to be considered limited to this example of implementation, all those variations and modifications falling within its scope or exemplifications covered by the appended claims, _24_ such as a different distribution strategy of the torque, a lower number of drive wheels, etc. The method and 11 vehicles described above present numerous advantages. First, the variable distribution of action braking performed by electric motors on each individual wheel during braking in combination with a hydraulic system how ABS, depending on the dynamic situation, maximizes or in any case improves the recovery of electrical energy during braking, also avoiding penalizing the action of control in dynamic situation. Finally, the control method described above is simple and economical implementation in a road vehicle equipped with a motor for each drive wheel, as it does not require an addition of any physical component and is completely realizable via software in vehicles equipped with at least two electric motors. It is important to note that the control method described above It does not require a high computing capacity or a large amount of data. of memory and therefore its implementation is possible in a unit of known control without the need for updates or upgrades. LIST OF REFERENCE NUMBERS OF THE FIGURES 1 road vehicle 2 front axle 3 rear axle 4 front wheels rear wheels propulsion system electric motors control circuitry control or calculation unit suspension shock absorber detection system braking system braking element brake pedal storage system battery pack hydraulic unit mechanical brakes right front wheel left front wheel right rear wheel left rear wheel A BS anti-lock braking system longitudinal acceleration A xXR driver request transversal battery operating conditions key value _26_ dynamic data driver first electric braking pair condition of electric motors vertical load adhesion factor interval interval mechanical braking torque maximum braking capacity priority functions and safety limitation longitudinal speed axis axis ass and

Claims

1) Control method for regenerative braking of a road vehicle (1) driven by a driver (DR); the road vehicle (1) comprising four wheels (4, 5), of which two or four wheels (4, 5) are driving wheels, arranged in pairs on a front axle (2) and / or a rear axle (3), each of which can be rotated by a respective electric motor (7) connected to it; the method comprises the phases of: - estimating, at least for each driving wheel (4, 5), independently of the other driving wheel(s) (4, 5), a respective factor (G) of adhesion to the ground travelled by the road vehicle (1); - defining or detecting, at least for each driving wheel (4, 5), independently of the other driving wheel(s) (4, 5), a respective vertical load (Fz) acting on it;- process, for each driving wheel (4, 5), a value of a maximum braking capacity (MRT) as a function at least of the respective grip factor (G) and the respective vertical load (Fz); - control a braking system (13), following a braking request by the driver (DR), so as to operate a hydraulic unit (18) to exert a first braking torque (mBT) at least on each driving wheel (4, 5); - control the braking system (13), in addition to the respective first braking torque (mBT), so as to operate in generative electric braking, delivering a respective second braking torque (eBT), each driving wheel and therefore the respective electric motor (7), at least as a function of the respective maximum braking capacity value (MRT) and in particular of the first torque (mBT), so as to generate recuperative electric energy;- modulate, at least for each driving wheel (4, 5), the first braking torque (mBT) and / or the second braking torque (eBT) so that the sum of the first braking torque (mBT) and the second torque (eBT) is, instant by instant, equal to or lower than the respective maximum braking capacity value (MRT); - store the recuperative electrical energy generated by the regenerative braking of each driving wheel (4, 5) in a vehicle electrical energy storage system (16).; 2) Method according to claim 1, wherein the hydraulic unit (18) comprises an anti-lock braking system (ABS), which, when activated, determines the modulation of the first braking torque (mBT). 3) Method according to claim 2, wherein, during at least part, in particular during the whole, - 29 of the activation of the anti-lock braking system (ABS), i.e. during the modulation of the first torque (mBT), the second braking torque (eBT) is controlled to a respective constant carrier value (BV) for each driving wheel (4, 5). 4) Method according to claim 3, wherein the load-bearing value (BV) corresponds to a predefined percentage of the maximum braking capacity (MRT) of said driving wheel (4, 5). 5) Method according to claim 3 and comprising the further steps of: - detecting a plurality of data (DD) on the vehicle dynamics; and - calibrating the respective carrier value (BV) of the second braking torque (eBT) as a function of the data (DD) on the vehicle dynamics. 6) Method according to any of the preceding claims, wherein during the modulation phase, for each driving wheel (4, 5), the second braking torque (eBT) is controlled in accordance with the respective value of the maximum braking capacity (MRT) of said driving wheel (4, 5). 7) A method according to claim 6, wherein the second torque (eBT) is controlled to correspond, under predefined conditions, to a predefined regenerative percentage of the respective maximum braking capacity (MRT) value. 8) Method according to claim 7, wherein the predefined conditions include at least the maximum braking capacity (MRT) sections that are constant and / or decreasing over time. 9) Method according to any of the preceding claims, wherein during the phase of controlling the braking system (13), at least one right wheel (4, 5) and one left wheel (4, 5) driving the same front and / or rear axle (2) are controlled independently of each other, distributing the regenerative braking between them in a differentiated manner. 10) Method according to any of the preceding claims, wherein the drive wheels (4, 5) are four, and wherein during the phase of controlling the braking system (13), the wheels (4, 5) of the front axle (2) and the wheels (4, 5) of the rear axle (3) are controlled independently of each other, distributing the regenerative braking in a differentiated manner between the front axle (2) and the rear axle (3). 11) A method according to any of the preceding claims, wherein the respective braking torque delivered by a wheel (4, 5) is dynamically variable over time, in particular with update frequencies greater than 5 Hz; more particularly with update frequencies equal to or greater than 10 Hz. 12) Method according to any of the preceding claims, wherein the first braking torque (mBT) delivered by the hydraulic unit (18) is independent for each wheel (4, 5) of the front axle (2) and / or the rear axle (3) respectively and / or between the pair of wheels (4, 5) of the front axle and the pair of wheels (4, 5) of the rear axle. 13) Electric road vehicle (1) comprising: - a front axle (2) and a rear axle (3); - four wheels (4, 5), of which two or four driving wheels (4, 5) arranged in pairs on a front axle (2) and / or a rear axle (3); - a propulsion system (6) comprising two or four electric motors (7), or alternatively one or two electric motors connected to active differentials each connected to two driving wheels (4, 5), each of the electric motors (7) being connected to a respective wheel (4, 5) or to two wheels in the case of the presence of active differentials; wherein each wheel (4, 5) can be rotated by the respective electric motor (7) connected to it; - an electronic control circuitry, which is configured to: o estimate, for each driving wheel (4, 5), independently of the other driving wheels (4, 5), a respective factor (G) of grip on the ground travelled by the road vehicle (1);or define or detect, for each driving wheel (4, 5), independently of the other driving wheels (4, 5), a respective vertical load (Fz) acting on it; or process, for each driving wheel (4, 5), a value of a maximum braking capacity (MRT) as a function of at least the respective adhesion factor (G) and the respective vertical load (Fz); - a braking system (13), comprising in turn at least one braking element (14) operable by the driver (DR) to request braking, in particular a pedal; wherein the braking system (13) also comprises a hydraulic unit (18), and mechanical brakes, controlled by the hydraulic unit (18); the braking system (13) being connected to the control circuitry (8) and configured to be controlled by it;wherein the control circuitry (8) is further configured to: control the braking system (13), following a braking request from the driver (DR) via the braking element (14), so as to operate the hydraulic unit (18) to exert a first braking torque (mBT) at least on each driving wheel (4, 5); control the braking system (13), in addition to the respective first braking torque (mBT), to operate in generative electric braking, delivering a respective second braking torque (eBT), each driving wheel and therefore the respective electric motor (7), as a function of the respective maximum braking capacity value (MRT) and in particular of the first torque (mBT), so as to generate recuperative electric energy;modulate, at least for each driving wheel (4, 5), the first braking torque (mBT) and / or the second braking torque (eBT) so that the sum of the first braking torque (mBT) and the second torque (eBT) is, at any given moment, equal to or lower than the respective maximum braking capacity value (MRT); and store the recuperative electrical energy generated by the regenerative braking of each wheel (4, 5) in a vehicular electrical energy storage system (16).; 14) A road vehicle (1) according to claim 13, wherein the control circuitry (8) is configured to carry out the method according to any of claims 1 to 12.