Dynamic braking method consisting of braking a rear wheel of the vehicle in the event of failure of the hydraulic braking system

Abstract

Dynamic braking method applicable to a motor vehicle equipped with a brake pedal, a hydraulic braking system intended to operate while the vehicle is moving and a parking brake with an electromechanical actuating unit, the method consisting of braking a rear wheel of the vehicle in the event of a failure of the hydraulic braking system. The method consists of first placing the electromechanical unit in a dynamic state by consuming the functional clearances of the parking brake, in anticipation of a braking need expressed by the driver on the brake pedal, then applying a clamping force to the parking brake in its dynamic state when a braking need is expressed by the driver. Figure for abstract: no figure

Description

Title of the invention: Dynamic braking method consisting of braking a rear wheel of the vehicle in the event of failure of the hydraulic braking system

[0001] The invention relates to the technical field of electric parking brakes, and in particular the field of the use of electric parking brakes during dynamic braking.

[0002] As described in document US 7,744,166, a parking brake is implemented electrically and / or automatically by an electromechanical unit, also called an electric actuator, associated with one or more of the rear wheels of the vehicle. Thus, a user of the vehicle wishing to engage the parking brake simply needs to press a push button, located for example on the dashboard near the steering wheel, to trigger or terminate the application of the parking brake around the wheel of the vehicle.

[0003] Also known, in particular from document US 7,721,853, is a single-block brake housing which contains both a hydraulic unit for braking while driving and an electromechanical unit for parking braking. By definition, these two units are not designed to operate at the same time, but their integration into a single housing facilitates assembly and saves space.

[0004] It is known that the presence of an electrically controlled parking brake makes it possible to use the electromechanical unit, normally dedicated to parking braking, as an emergency braking system in the event of failure of the hydraulic unit. The driver can thus stop the vehicle using the electric parking brake control button. This functionality is a common requirement of car manufacturers. The driver must be able to stop the vehicle using the electric parking brake control button that applies to the rear wheels.

[0005] For this purpose, an algorithm is implemented which is illustrated by [Fig.l], in which it can be seen that from an initial operating state 1 of application of an emergency braking application by the electromechanical unit, the application of the brake is stopped in the event of slippage greater than a first predetermined slippage threshold, by moving to a stop state 2. From this stop state 2, if the slippage continues to increase and passes above a second slippage threshold, the application is released by moving to a release state 3. From this release state 3, if the slippage falls below the second slippage threshold, the application is maintained by moving to a hold state 4. From this hold state 4, if the slippage falls below a threshold relocking, then we return to state 1 of applying a tightening. Note that three parameters are necessary for the execution of this algorithm: the first threshold, the second threshold and the relocking threshold. The measurements necessary for this execution are the wheel speeds, which allow the level of slip to be measured.

[0006] This known multi-threshold braking method is called RWU, for "Rear Wheel Unlocker". It consists of using the parking brake on the rear wheels to brake them without locking them. In short, if a wheel locks, the brake is released to unlock the wheel, then it is re-tightened, etc.

[0007] In electrical terms, the execution of the method results in the physical quantities of electric current 5 and control signal 6 illustrated in [Fig.2], compared with the activation of the braking by the driver 6 and the clamping force 7 applied to the brake by the electromechanical unit.

[0008] The actuator thus passes through three states: release 6a, tightening 6b, loosening 6c.

[0009] This method is inspired by the hydraulic anti-lock braking system marketed under the brand name ABS, but differs from it in that it uses electrical control of the brake motor. It requires operational operation of the speed sensors of at least one front wheel and both rear wheels.

[0010] To address situations where no front wheel speed sensor is operational or at least one rear wheel speed sensor is inoperative, an incremental braking force braking method has been proposed.

[0011] In all cases, the desired goal is achieved, namely stopping the vehicle, but the braking performance is limited and a deceleration of between 0.15g and 0.3g is obtained.

[0012] In addition, the RWU or incremental force braking methods have some other disadvantages, which are not prohibitive but leave room for improvements.

[0013] First of all, deceleration is not adjustable. It depends mainly on the condition of the road and the weight of the vehicle.

[0014] As a corollary, wheel locking situations occur quite frequently during such braking, due to the sudden and relatively late increase in the clamping force, which seeks above all maximum braking to aim for optimal safety.

[0015] Thus, in [Fig.3], where we see the evolution over time of: - the electrical voltage 8 supplying the controllers of the electric motors of the electromechanical unit, - deceleration 9 in m / s2, - command 10 for applying the parking brake, - the electric current 11 applied to the electric motor of the left rear wheel, - the electric current 12 applied to the electric motor of the right rear wheel, - the control 13 of the electric motor of the left rear wheel, - the control 14 of the electric motor of the right rear wheel, - state 15 of the left rear wheel brake actuator, - state 16 of the right rear wheel brake actuator, - speed 17 of the left front wheel, - speed 18 of the right front wheel, - left rear wheel speed 19, - speed 20 of the right rear wheel, - the slip coefficient 21 of the left rear wheel, - the slip coefficient 22 of the right rear wheel,

[0016] it is noted that the rotation speeds 19 and 20 of the rear wheels are zero for a relatively long period of time due to the slip coefficients 21 and 22 being too high. The effectiveness of the emergency braking is therefore not always optimal.

[0017] This results in vehicle stability that is imperfect, or at the very least uncomfortable for its passengers. Similarly, braking precision is lacking, since it is by definition always at its maximum.

[0018] As a result, the electromechanical unit is currently only used to perform emergency braking when the hydraulic unit is out of service. Braking during normal driving is not sufficiently comfortable to be considered.

[0019] There is therefore a need for an emergency braking solution in the event of a malfunction of the hydraulic unit, which provides a braking mode adjusted to the driving circumstances, i.e. which responds in a proportionate manner to the braking requests expressed by the driver when he presses the brake pedal.

[0020] Preferably, in order to avoid causing instabilities, the emergency brake should: - adapt the braking force to the slippage of the roads, - manage each wheel individually - take into account vehicle speed, lateral acceleration and the road friction coefficient.

[0021] Preferably, the emergency brake should allow a driver to drive his vehicle with a defective hydraulic braking system to a repairer. For this purpose, the deceleration should be moderated depending on the depression of the brake pedal and, for example, the modulation of the deceleration should depend on the position of the brake pedal. In addition, the responsiveness of the electromechanical unit should be improved, so that the reaction time of the brake is not too long, compared to when the hydraulic unit commands it.

[0022] Finally, when necessary, the overall deceleration of the vehicle should reach better performance, for example 0.5g instead of capping at 0.3g.

[0023] Another object of the invention is to be able to obtain this adjusted braking solution by using a single-box brake containing both a hydraulic unit for driving braking and an electromechanical unit for parking braking.

[0024] The invention mainly relates to a dynamic braking method applicable to a motor vehicle equipped with a brake pedal, a hydraulic braking system intended to operate while the vehicle is moving and a parking brake with an electromechanical actuating unit, the method consisting of braking a rear wheel of the vehicle in the event of a failure of the hydraulic braking system, characterized in that it consists of first placing the electromechanical unit in a dynamic state by consuming the functional clearances of the parking brake, in anticipation of a braking need expressed by the driver on the brake pedal, then applying a clamping force to the parking brake in its dynamic state when a braking need is expressed by the driver.

[0025] In a particular embodiment of the invention, the dynamic state consists of: - if the parking brake is released: recalibrate the electromechanical unit by applying a temporary increase in current to its electric motor, then release the parking brake by returning to the initial current for a release period, - if the parking brake is activated, release the parking brake for a release time, - if the parking brake is already used as an emergency brake because the process has already started during a previous cycle, release for a release time.

[0026] In a particular embodiment of the invention, the application of the clamping force consists of: - recover a braking request from the driver in the form of a clamping force instruction determined according to the way in which the driver pressed said pedal, - modifying the electrical supply to the motor of the electromechanical unit to increase the application force of the parking brake, first achieved by applying a predetermined increase in electrical current to the motor, then increasing the application force by successive brief applications of current each having a predetermined duration.

[0027] According to other optional characteristics of the method, taken alone or in combination: - the predetermined excess electric current to the motor is 1 A, - the predetermined duration of the brief applications is 50 ms, - the number of successive current applications is limited to a value between between 6 and 12, preferably 9, for dynamic mode and between 3 and 7 for static mode.

[0028] The main advantages of the invention are as follows: - modulation of the braking force of the electric parking brake according to the driver's request on the brake pedal. It is no longer a question of activating the parking brake with a button. The driver brakes as if his main braking system were still operational, and depending on the travel of the brake pedal and / or the hydraulic pressure, the braking force of the parking brake is adjusted. - increased precision thanks to a reduction in brake response time, taking into account the position of the brake pedal and an improvement in release thanks to step-by-step actions. All while maintaining the principle of wheel speed control to ensure vehicle stability. - adaptation to automatic parking brake systems of different types, guaranteeing good braking performance: bite, linearity, comfort and controllability.

[0029] In other words, the invention proposes to detect the failure of the hydraulic system to reduce the functional clearances in order to guarantee a faster response time, before creating a braking force of the parking brake proportional to the driver's pressure on the brake pedal. This reduced clearance is maintained as long as the function is active and the hydraulic system is faulty.

[0030] The invention also relates to a motor vehicle equipped with a brake pedal, a hydraulic braking system intended to operate while the vehicle is moving and a parking brake with an electromechanical actuating unit, which comprises a brake pedal travel sensor, an electronic stability control computer and means for implementing the method described above. Brief description of the figures

[0031] The invention will be better understood on reading the following description given solely by way of example and with reference to the appended drawings in which:

[0032] [Fig.l] illustrates a known algorithm for dynamic braking, i.e. during the rolling of the vehicle, by the electromechanical parking brake control unit,

[0033] [Fig.2] is a graph representing, as a function of time, the braking command, the electric current flowing in the electromechanical unit, the braking force and the state of the actuator, in a state-of-the-art braking system used by following the algorithm of [Fig.l],

[0034] [Fig.3] is a graph bringing together different measurements of electrical voltage, current electrical, deceleration, control signal, state, speed, slip coefficient performed during use of the braking system of [Fig.2],

[0035] [Fig.4] is a logic diagram illustrating the exchange of information between the cal electronic vehicle stability control (ESC) controller and the brake control device, when implementing the method according to the described embodiment of the invention,

[0036] [Fig.5] illustrates the application of the braking force and its regulation as a function of driver pressure on the brake pedal and wheel slippage,

[0037] [Fig.6] and [Fig.7] are two graphs gathering different voltage measurements electric, electric current, deceleration, control signal, state, speed, slip coefficient carried out during use of the braking system by implementing the method according to the described embodiment of the invention,

[0038] [Fig.8] is a graph showing the decelerations obtained in the event of failure of the hydraulic brake thanks to the method according to the described embodiment of the invention, alone and combined with regenerative braking, compared to the deceleration obtained without the invention. Detailed description

[0039] [Fig. 4] shows a logic diagram of the data exchanges occurring between the vehicle's electronic stability control (ESC) computer 30 and the control device 40 of the parking brake 41, in a particular embodiment of the method of the invention. In this example, the parking brake 41 is a disc brake.

[0040] The input physical quantities are: 23: pedal travel sensor (PTS) 24: pressure in the master cylinder (pressure master cylinder (pMC) in Anglo-Saxon terminology)

[0041] The electronic stability control computer of the vehicle 30 contains a controller trigger 31 which takes into account the position of the brake pedal (not shown) and its crossing of a predetermined threshold position, beyond which a brake application must be applied, as indicated by the instruction 25 sent by the trigger 31 to the control device 40, to determine a clamping force which is supplied to the control device 40 as a setpoint value. This value is determined on the basis of the driver's request, represented by the arrow 26, itself translated by his manner of pressing the pedal (not shown). A logic, deterministic or possibly based on artificial intelligence, is implemented by computer means (not shown) to determine this clamping force setpoint to be supplied to the control device 40.The pedal position is one of the input parameters of this logic, provided by the . pedal stroke sensor 23.

[0042] At the same time, the electronic stability control computer of the vehicle 30 transmits to the control device 40 information 27 of a malfunction of the hydraulic braking unit. This information results in a command to switch the parking brake to dynamic mode.

[0043] Switching to dynamic mode

[0044] When a malfunction of the hydraulic braking unit occurs, the control device 40 is informed by the electronic stability control computer of the vehicle 30 and places itself in dynamic mode 42 so as to prepare the electromechanical unit to assist in braking in the event of a request from the driver.

[0045] Three situations are then possible.

[0046] 1st situation: the brakes are released.

[0047] The control device 40 begins the recalibration of the electromechanical unit by applying a temporary increase in current to the electric motor of said electromechanical unit. The increase in current is, in the example, 1 A. A value between 0.5 A and 1.5 A is preferred.

[0048] Immediately after this increase in intensity, a release is applied by a return to the initial intensity for a release duration which, in the example, is 50 ms. A duration of 100 ms is another possible example. A residual brake application torque is thus limited.

[0049] 2nd situation: the parking brakes are activated.

[0050] The control device 40 temporarily releases the parking brakes. The duration of the release is, in the example, 50 ms. A residual brake application torque is thus limited.

[0051] 3rd situation: the brakes are already used as emergency brakes because the process has already started during a previous cycle.

[0052] A release is applied for a release duration which, in the example, is 50 ms. A residual brake application torque is thus limited.

[0053] Once the electromechanical unit is in dynamic mode, it is ready to respond to a braking request from the driver.

[0054] Driver request

[0055] When the vehicle's electronic stability control computer 30 transmits a braking request from the driver, in the form of a clamping force setpoint determined as a function of the way in which the driver has pressed said pedal, the control device 40 modifies the electrical power supply to the motor of the electromechanical unit to increase the clamping force of the parking brake. The increase in the clamping force is first achieved by applying an additional predetermined amount of electric current to the motor (1 A in the example described). Then the clamping force is increased by brief successive applications of current, each having a predetermined duration (50 ms in the example described). These brief successive applications ensure good progressiveness and allow the targeted deceleration to be achieved. At least N applications of the predetermined duration are necessary to ensure that the targeted deceleration level is achieved while maintaining good vehicle stability. In the example described, N is 9. N can range from 6 to 12 if the vehicle is moving and from 3 to 7 if the vehicle is stationary.

[0056] The right and left rear wheel brakes are independently controlled for driver convenience.

[0057] If slippage is detected, a release may be applied for a release time of between 50 ms and 90 ms to ensure good responsiveness and avoid instability on slippery roads with low coefficient of adhesion (mue).

[0058] The clamping force is adjusted by brief applications or brief releases, depending on the driver's demand.

[0059] More specifically, with reference to [Fig.5], we will describe in detail each of the state changes of the algorithm. Each rear wheel, left and right, follows its own algorithm sequence, independently of the other.

[0060] From the entry point 43 of the dynamic mode, the control device 40 begins with a test 44 which makes it possible to check the slip state of the wheel. If the slip coefficient is lower than a predetermined threshold for triggering a new cycle, this means that the slip is sufficiently low to start a tightening cycle. We enter the “application” state, “first application” sub-state 45.

[0061] When the cycle begins, the on-board computer 30 provides the clamping force setpoint. The clamping force is increased by incrementing by 1 A the electrical intensity of the current supplying the motor of the electromechanical unit.

[0062] From this state 45, a test 46 is used to check whether the electric current at the motor terminals is greater than a threshold value, which is defined as the value corresponding to the tightening instruction. If this is already reached, the state “stop” 47 is moved to. Similarly, the test 48 determines whether the slip becomes too significant because it is greater than a tightening end threshold. Then, the same state “stop” 47 is moved to.

[0063] Otherwise, after expiration 49 of a predetermined duration, the state “stop” 47 is switched to.

[0064] From the “stop” state 47, a test 50 is used to check that the current in the motor has not not yet reached the value corresponding to the brake application setpoint and the slip remains below the end of application threshold. If this is the case, we return to the “application” state, but in the “brief application” sub-state 51.

[0065] A test 52 determines whether the slip is greater than a release threshold. We then move to a “release” state 53.

[0066] Another test 54 determines whether the current in the motor is less than the value corresponding to the brake application setpoint. We then also move to the “release” state 53.

[0067] From the “brief application” sub-state 51, after expiration 49 of a predetermined duration, it is verified by the test 48 that the sliding is still suitable, then it is returned to the “stop” state 47, etc.

[0068] From the “first application” state 45, a test 55 determines when the duration of the brief applications has expired or when the intensity corresponding to the tightening instruction has been reached, we move to the “release” state 53 and the tightening force instruction is reset to zero.

[0069] From the “release” state 53, after expiration 56 of a predetermined duration, we return to the “stop” state 47, unless a test 57 determines that a braking request is expressed in the form of a new instruction (which may be the same as previously because the need for braking continues) and that the slip becomes lower than the release threshold. Then, we return to the entry point 43.

[0070] A test 58 determines whether no braking request is expressed. Then, we move to a “waiting” state 59, a state that we will leave if a test 60 confirms that a non-zero braking instruction is again expressed, independently of the slip, to reach the entry point 43.

[0071] In this algorithm, the main parameters are: - slip coefficient for stopping, - slip coefficient for release, - slip coefficient for new cycle, - target current for first application, - short application duration.

[0072] The main input data are: - speed of front and rear wheels, right and left, - target braking force provided by the vehicle's electronic stability control computer.

[0073] The main states are: - “application”, with two sub-states “first application” and “brief application”, - " stop ", - "relaxation", - “entry point”.

[0074] The thresholds can be adapted according to the speed of the vehicle.

[0075] In particular, a distinction can be made depending on whether the vehicle is moving at more than 10 km / h or less than 5 km / h, it being understood that the thresholds of 5 km / h and 10 km / h are steps adjustable meters depending on the vehicle and specifications.

[0076] The following Table 1 shows the nominal values ​​to be used for a vehicle moving at more than 10 km / h.

[0077] [Tables 1] clamping target (%) 20 30 40 50 60 70 80 90 100 target current (A) 2 2.5 3 3.5 4 4.5 5 5.5 6 N 1 2 3 4 5 6 7 8 9 Target Idle + IA + 50ms 50ms 50ms 50ms 50ms 50ms 50ms 50ms

[0078] The following table 2 shows the values ​​to be used for a vehicle moving at less than 5 km / h.

[0079] [Tables2] Tightening target (%) 20 30 40 50 60 70 80 90 100 Target current (A) 1 1 1 1.5 2 2.5 3 3.5 4 N 1 2 3 4 5 6 7 8 9 Target Idle + 0.7A Iso step 1 Iso step 1 50ms 50ms 50ms 50ms 50ms 50ms Other settings: - Short application duration: 50 ms - Release delay: no-load current (also called “idle”) + 50 ms

[0080] Figures 6 and 7 show the different signals and physical quantities reflecting the evolution of the wheels and the electromechanical unit during braking.

[0081] In detail, these signals and quantities are: - parking brake control 10, - deceleration 9 in m / s2, - state 15 of the left actuator, - state 16 of the right actuator, - the effort required (%) 61, - master cylinder pressure (bar) 24, - speed 17 of the left front wheel, - speed 18 of the right front wheel, - left rear wheel speed 19, - speed 20 of the right rear wheel, - the slip coefficient 22 of the left rear wheel, - control 13 for applying the left parking brake, - state 66 of the left parking brake power stage, - the electric current 11 applied to the left electric motor, - left tightening instruction 62, - left tightening value 63 reached, - the slip coefficient 21 of the right rear wheel, - control 14 for tightening the right parking brake, - state 67 of the right parking brake power stage, - the electric current 12 applied to the right electric motor, - right tightening instruction 64, - the right tightening value 65 reached.

[0082] As seen in [Fig.6], the longitudinal acceleration is progressive and directly linked to the driver's wishes.

[0083] The actuators are managed independently by short applications. The short applications are suspended if a slip is detected.

[0084] As seen in [Fig.7], the actuators are managed independently in case of slip detection. A short release duration is adjusted according to the duration of the slip.

[0085] In [Fig.8], the deceleration obtained in three circumstances of faulty hydraulic braking is shown: - by the embodiment described: curve 68, - by the embodiment described, combined with regenerative braking, because the vehicle is hybrid or electric: curve 69, - braking with support of the non-controlled parking brake according to the invention: curve 70.

[0086] The example described above concerns a disc parking brake.

[0087] The invention also applies to the case of a drum brake. It is then appropriate to adapt the parameters as follows.

[0088] The clamping force is increased by starting with a first increment, for example 1 A, as for a disc brake.

[0089] A release is applied by applying a protective current so as to avoid a backstop detection.

[0090] Brief applications under the same clamping force are iterated, to the maximum number of N, where N is between 6 and 12 in dynamic mode and between 3 and 7 in static mode. The duration of the brief applications is fixed between 30 ms and 80 ms.

[0091] For a drum brake, the recalibration phase is adapted to ensure a force appropriate tightening.

[0092] Since the behavior of a drum brake is less linear than that of a disc brake, the clamping force profile is different, as are the clamping parameters for applying the method according to the invention. In particular, it is necessary to increase the safety margins to avoid too high a force at the rear stop.

[0093] Table 3 relates to a vehicle equipped with a drum parking brake traveling at more than 10 km / h.

[0094] [Tables3] Target clamping (%) 20 30 40 50 60 70 80 90 100 Target current (A) 2 2.5 3 3.5 4 4.5 5 5.5 6 N 1 2 3 4 5 6 7 8 9 Target Idle +1A + 50ms 50ms 50ms 50ms 50ms 50ms 50ms 50ms

[0095] Table 4 relates to a vehicle equipped with a drum parking brake traveling at less than 5 km / h and having a target application force of less than 5%.

[0096] [Tables4] Tightening target (%) 20 30 40 50 60 70 80 90 100 Target current (A) 1 1 1 1.5 2 2.5 3 3.5 4 N 1 2 3 4 5 6 7 8 9 Target Idle + 0.7A Iso step 1 Iso step 1 50ms 50ms 50ms 50ms 50ms 50ms Other settings: - Short application duration: 50 ms - Release delay: no-load current (also called “idle”) + 70 ms

[0097] A release is applied, as for a disc brake, but increased compared to a disc brake.

[0098] The invention is not limited to the embodiments presented and other embodiments will become clear to those skilled in the art.

[0099] List of references 1 . . . initial operating condition 3 . . . state of relaxation 4 . . .holding state 5 . . .electric current 6 . . .control signal 7 . . .clamping force 9 . . .deceleration 10 . . .brake control 11.. .electric current applied to the left electric motor 12 . . .electric current applied to the right electric motor 13 . . .right parking brake application control 14 . . .left parking brake application control 17 . . .the speed of the left front wheel 18 . . .the speed of the right front wheel 19 ... the speed of the left rear wheel 20 ... the speed of the right rear wheel 21 . . . right rear wheel slip coefficient 22 . . . left rear wheel slip coefficient 23 . . . PTS 25 . . . application of a brake application 26 . . . driver's request 30 . . . vehicle electronic stability control (ESC) computer 31... controller trigger 40 . . . control device 41 . . . parking brake 42 . . . dynamic mode 43 . . . entry point 44 . . . checking the wheel sliding condition 45 . . . state “first application” 46 . . . checking whether the electric current at the motor terminals is greater than a threshold value 47 . . . “stop” state 48 . . . check if the slip becomes too significant 49 . . . predetermined duration 50 . . . checking motor current and slip 51... “brief application” status 52 . . . checking whether the slip is greater than a release threshold 53 . . . “relaxation” state 54 . . . checking whether the current in the motor is less than the value corresponding to the brake application instruction 55 . . . verification of the duration of short applications and the intensity 56 . . . predetermined duration 57 . . . checking whether a braking request is expressed 58 . . . check if no braking request is expressed 59 . . . "waiting" state 60 . . . verification of a non-zero braking instruction 61 . . . effort required 62 . . . left tightening instruction 63 . . . left clamping value reached 64 . . . right tightening instruction 65 . . . right tightening value reached 66 . . . status of the left parking brake power stage 67 . . . status of the right parking brake power stage, 68 . . . deceleration obtained with the embodiment described 69 . . . deceleration obtained with the embodiment described, combined with regenerative braking 70 . . . deceleration obtained with support of a non-controlled parking brake according to the invention

Claims

Claims

1. Dynamic braking method applicable to a motor vehicle equipped with a brake pedal, a hydraulic braking system intended to operate while the vehicle is moving and a parking brake with an electromechanical actuating unit, the method consisting of braking a rear wheel of the vehicle in the event of a failure of the hydraulic braking system, characterized in that it consists of first placing the electromechanical unit in a dynamic state by consuming the functional clearances of the parking brake, in anticipation of a braking need expressed by the driver on the brake pedal, then applying a clamping force to the parking brake in its dynamic state when a braking need is expressed by the driver.

2. Method according to claim 1, in which the dynamic state consists of: - if the parking brake is released: recalibrating the electromechanical unit by applying a temporary increase in current to its electric motor, then releasing the parking brake by returning to the initial current for a release period, - if the parking brake is activated, releasing the parking brake for a release period, - if the parking brake is already requested as an emergency brake because the method has already started during a previous cycle, releasing for a release period.

3. A method according to claim 1, wherein the application of the clamping force consists of: - recovering a braking request from the driver in the form of a clamping force setpoint determined as a function of the way in which the driver has pressed said pedal, - modifying the electrical supply to the motor of the electromechanical unit to increase the clamping force of the parking brake, first carried out by applying a predetermined increase in electrical current to the motor, then by increasing the clamping force by brief successive applications of current each having a predetermined duration.

4. A method according to any preceding claim, wherein the predetermined excess electrical current to the motor is 1

5. A. A method according to any preceding claim, wherein the predetermined duration of the brief applications is 50 ms.

6. Method according to any one of the preceding claims, in which the number of successive applications of current is limited to a value between 6 and 12, preferably 9, for the dynamic mode and between 3 and 7 for the static mode.

7. Motor vehicle equipped with a brake pedal, a hydraulic braking system intended to operate while the vehicle is moving and a parking brake with an electromechanical actuating unit characterized in that it comprises a brake pedal travel sensor, an electronic stability control computer and means for implementing the method according to any one of claims 1 to 6.

Images