METHOD FOR CONTROLLING AN ELECTRIC VACUUM PUMP IN A VACUUM BRAKING SYSTEM FOR A VEHICLE

Abstract

A method for controlling an electric vacuum pump (2) in a vacuum braking system for a vehicle, comprises the steps of:- measuring a pressure in the braking system, and- controlling the pump (2) according to a continuous operating mode or a periodic operating mode, the control of the vacuum pump (2) switching from the continuous operating mode to the periodic operating mode, and vice versa, at least as a function of the pressure measured in the braking system. Fig. 1

Description

Title of the invention: METHOD FOR CONTROLLING AN ELECTRIC VACUUM PUMP IN A VACUUM BRAKING SYSTEM FOR A VEHICLE Technical field

[0001] The present invention relates generally to a method for controlling an electric vacuum pump mounted on a motor vehicle. The invention also relates to a vacuum braking system for a vehicle, this vacuum braking system for the vehicle comprising an electric vacuum pump, the control of the electric vacuum pump being implemented by means of a method. The invention finally relates to a motor vehicle comprising such a vacuum braking system.

[0002] A motor vehicle is conventionally equipped with brake assistance, so as to reduce the force that the driver must exert with his foot on the brake pedal to obtain a braking effect, and if necessary a stopping of the vehicle. The most commonly adopted assistance is achieved by means of a depression generated in a chamber, forming a brake amplifier. The chamber is inserted in the braking system between the brake pedal and the master cylinder, the latter being connected to the hydraulic braking circuit. PRIOR ART

[0003] In this type of vacuum braking system, it is known in the prior art, for example from document EP2726351, that the necessary vacuum is typically generated by a vacuum pump. The vacuum pump is either mechanically driven by the vehicle's engine or by a dedicated electric motor. The need to maintain negative pressure is detected by a pressure sensor. The sensor controls the start-up of the electric vacuum pump according to activation and deactivation thresholds. As soon as a target vacuum level is reached in and / or the stopping conditions are met, the electric vacuum pump stops.

[0004] On the other hand, this vacuum braking system with an electric vacuum pump has the disadvantage of constantly requiring the vacuum pump when the driver presses the brake pedal hard or presses it at a high frequency. Long activations of the electric vacuum pump can cause damage to it in the long term. In addition, using the vehicle at altitude also means that the electric vacuum pump will have to operate for longer periods in order to provide a satisfactory vacuum reserve.

[0005] In the case of an electric vehicle, the vacuum pump constitutes the vehicle's main vacuum generation system. It will actually be more stressed in terms of activation and activation duration than on a hybrid engine vehicle, where it remains possible to switch to a vacuum pump coupled and mechanically driven by the engine.

[0006] In the event of prolonged use, the vacuum pump may thus overheat and / or its constituent parts may be damaged. A failure of the electric vacuum pump no longer allows correct braking performance to be ensured for the driver. Summary of the invention

[0007] An aim of the present invention is to overcome the drawbacks of the prior art mentioned above and in particular, first of all, to ensure protection of the electric vacuum pump in the event of high loads.

[0008] For this, a first aspect of the invention relates to a method for controlling an electric vacuum pump in a vacuum braking system for a vehicle.

[0009] The method comprises the steps of: - to measure pressure in the braking system, and - to control the electric vacuum pump according to a continuous operating mode or a periodic operating mode, the control of the electric vacuum pump switches from the continuous operating mode to the periodic operating mode, and vice versa from the periodic operating mode to the continuous operating mode, at least as a function of the pressure measured in the vacuum braking system.

[0010] In other words, the invention consists of providing for a method of controlling a vacuum pump an additional operating mode, which will be periodic with thus a functional periodic activation. The periodic activation makes it possible to activate the vacuum pump for a duration of a few seconds, to deactivate it for another duration of a few seconds, then to re-engage it and so on, all the time that the vehicle will be in a specific situation.

[0011] The vacuum requirement is thus detected by a pressure sensor. The invention consists of being able to switch to a more optimized control mode for the vacuum pump, before arriving in a situation where it will no longer be able to correctly provide vacuum to the driver to be able to brake his vehicle. Such control for the vacuum pump will make it possible to increase its availability on the vehicle, and to increase its durability, by avoiding excessively long activation times. The heating of the vacuum pump will be limited.

[0012] Advantageously, the control of the vacuum pump can switch from continuous operating mode to periodic operating mode, when the following conditions are simultaneously met: - a continuous activation duration of the vacuum pump is greater than a first determined duration, or when the measured pressure is greater than a lower continuous activation pressure threshold and the measured pressure is less than or equal to an upper continuous deactivation pressure threshold, and - a vehicle speed is lower than a threshold speed, and - a vehicle altitude is between a minimum altitude and a maximum altitude.

[0013] As soon as the vacuum pump runs for too long, the continuous operating mode of the electric vacuum pump stops and the periodic operating mode can begin, if the mentioned preconditions allow it. The pressure sensor controls the switching on of the electric vacuum pump according to two thresholds, a lower continuous activation threshold and an upper continuous deactivation threshold. As soon as a target vacuum level is reached and / or as soon as the stopping conditions are met, the electric vacuum pump stops. The activation of the functional periodic mode will only take place following a long continuous activation, in order to avoid any overheating or damage to the electric vacuum pump and in order to continue to guarantee the vacuum supply performance in the vacuum braking system.The activation of the periodic mode is also conditioned by a vehicle speed threshold (low), to favor its activation on more typical "city" routes and at altitudes for example below 3000m, in order to more precisely target life situations where the electric vacuum pump may be more heavily used, the continuous operating mode being able to be reactivated at any time if necessary. Operation of the vehicle below a threshold speed implies that the electric vacuum pump will operate for longer, in order to provide a satisfactory vacuum reserve, the continuous operating mode thus remaining activated. Operation at altitude also implies that the electric vacuum pump will operate for longer, in order to provide a satisfactory vacuum reserve, the continuous operating mode thus remaining activated.

[0014] Advantageously, the upper continuous deactivation pressure threshold may be higher than the lower continuous activation pressure threshold.

[0015] Advantageously, the control of the vacuum pump can switch from periodic operating mode to continuous operating mode, when only one of the following conditions is met: - the measured pressure is greater than or equal to an upper pressure threshold for periodic deactivation, - the measured pressure is lower than a lower pressure threshold for periodic activation, - the measured pressure is higher than an upper deactivation pressure threshold continuous and lower than the upper pressure threshold for periodic deactivation for a second determined duration, - the measured pressure is lower than a continuous lower activation pressure threshold and higher than a periodic lower activation pressure threshold for a third determined duration.

[0016] In other words, two additional thresholds are defined, and when the pressure exceeds the upper additional threshold, or when the pressure is lower than the lower additional threshold, the periodic operating mode can stop and the continuous operating mode can start again.

[0017] As soon as the measured pressure is greater than or equal to an upper pressure threshold for periodic deactivation, any mode of control of the electric vacuum pump is stopped, the target vacuum level in the vacuum braking system being reached. As soon as the measured pressure is lower than a lower pressure threshold for periodic activation, the control of the vacuum pump then switches back to continuous operating mode. As soon as the measured pressure is greater than an upper pressure threshold for continuous deactivation and lower than the upper pressure threshold for periodic deactivation for a second determined duration, the periodic mode is maintained for this second duration. The periodic mode stops at the end of this second duration, and the stopping of the activation of the electric vacuum pump is then authorized beyond this second duration, because the measured pressure is above the continuous deactivation threshold.As soon as the measured pressure is lower than a lower continuous activation pressure threshold and higher than a lower periodic activation pressure threshold for a third determined duration, the periodic mode stops after this third duration and the continuous operating mode of the vacuum pump is then reactivated beyond this time delay, because the measured pressure is below the continuous activation threshold.

[0018] Advantageously, the upper pressure threshold for periodic deactivation may be greater than the upper pressure threshold for continuous deactivation. Advantageously, the upper pressure threshold for continuous deactivation may be greater than the lower pressure threshold for continuous activation. And advantageously, the lower pressure threshold for continuous activation may be greater than the lower pressure threshold for periodic activation.

[0019] When the pressure oscillates between the upper pressure threshold for periodic deactivation and the upper pressure threshold for continuous deactivation, for a second determined duration, the periodic operating mode can stop once this second determined duration has expired and the stopping of the control of the electric vacuum pump in continuous mode or in periodic mode can be authorized. When the pressure oscillates between the lower pressure threshold for continuous activation and the threshold for lower pressure of periodic activation, for a third determined duration, the periodic operating mode can stop once this third determined duration has expired and the continuous operating mode can then start again.

[0020] Advantageously, the control of the vacuum pump can remain in the periodic operating mode beyond a fourth determined duration, when the measured pressure is greater than a lower continuous activation pressure threshold and less than or equal to an upper continuous deactivation pressure threshold.

[0021] The control of the vacuum pump can remain in the periodic operating mode beyond a fourth determined duration on the condition of having previously had a long continuous activation of the electric vacuum pump of more than 30s.

[0022] Advantageously, the method may comprise an additional step, in the event of overheating or damage to the vacuum pump, following long continuous activation, consisting of activating at least one of the following degraded modes, with: - sending a signal to the after-sales service, indicating a failure of the vacuum pump, - activation of a malfunctioning periodic control mode of the vacuum pump, - lighting of a warning light on the dashboard, corresponding to a vehicle fault, - activation of a hydraulic pump of an electronic stability control.

[0023] The after-sales service will be notified in the event of a vacuum pump failure. The vacuum pump will switch to an emergency operating mode which will allow at least one more braking of the vehicle. By the "stop" light being on, the driver will be notified of the failure and will stop his vehicle. Compensation strategies for the lack of braking assistance will be triggered by activation of a hydraulic pump of an electronic trajectory corrector, of the ESC or ESP type.

[0024] Advantageously, the control of the vacuum pump can be implemented using a vehicle engine computer.

[0025] A second aspect of the invention is a vacuum braking system for a vehicle, comprising an electric vacuum pump, the control of the vacuum pump being implemented according to the method according to the first aspect of the invention.

[0026] A final aspect of the invention is a motor vehicle comprising a braking system according to the second aspect of the invention. BRIEF DESCRIPTION OF THE FIGURES

[0027] Other characteristics and advantages of the present invention will appear more clearly on reading the following detailed description of an embodiment of the invention given by way of non-limiting example and illustrated by the drawings. annexed, in which:

[0028] [Fig. 1] represents an architecture of the implementation of the control method according to the present invention;

[0029] [Fig.2] represents the positioning of the different pressure thresholds, namely periodic deactivation, continuous deactivation, continuous activation, and periodic activation, relative to each other;

[0030] [Fig.3] represents a strategy for controlling the electric vacuum pump with activation and deactivation of the periodic operating mode and with activation and deactivation of the continuous operating mode;

[0031] [Fig.4a] represents, in dashed lines, a measured pressure evolution curve DP according to a first test case, measured in millibars, and in mixed dashes and dots, a measured pressure evolution curve DP according to a second test case, measured in millibars, in the vacuum braking system, as a function of time t expressed in seconds;

[0032] [Fig.4b] represents three curves of time count evolutions, measured in seconds, a first curve of the continuous operating mode, in solid line, and of the periodic operating mode, a first curve in dashed lines according to the first test case, and a second curve in mixed dashes-dots according to the second test case, according to the pressure evolution curve of [Fig.4a], as a function of time t expressed in seconds;

[0033] [Fig.4c] represents two curves for activation and deactivation of the continuous operating mode, a first curve in solid lines according to the first test case, and a second curve in mixed lines and dots according to the second test case, according to the pressure evolution curve of [Fig.4a], as a function of time t expressed in seconds; and

[0034] [Fig.4d] represents an activation and deactivation curve of the periodic operating mode, a first curve in solid lines according to the first test case, and a second curve in mixed lines and dots according to the second test case, according to the pressure evolution curve of [Fig.4a], as a function of time t expressed in seconds. DETAILED DESCRIPTION

[0035] In particular, reference is made to [Fig.l] showing an architecture 1 of the implementation of the method according to the present invention. An electric vacuum pump 2 in a vacuum braking system of a motor vehicle is controlled by an engine computer 3 (eVCU) of the vehicle. The functions related to the control method 4 of the vacuum pump 2 are embedded in the software present in the computer 3.

[0036] The eVCU calculator 3 is electrically connected to a pressure sensor 6, to a vehicle speed sensor 7, to an atmospheric pressure sensor 8, making it possible to determine the altitude of the vehicle, and to a sensor detecting the driver's pressure. on brake 9. Pressure sensor 6 measures the pressure DP within the vacuum braking system.

[0037] The vacuum pump 2 is connected to a computer of a trajectory corrector 11, known under the name “Electronic Stability Control” (ESC) or “Electronic Stability Program” (ESP). In the event of failure of the vacuum pump 2, a hydraulic pump linked to the computer of the trajectory corrector 11 is triggered. This compensation strategy 12 for lack of braking assistance 13, known under the name “Hydraulic Brake Boost” and “Hydraulic Brake Failure Compensation” (HBB / HBC), is embedded in the computer of the trajectory corrector 11.

[0038] In the event of a failure of the vacuum pump 2, a degraded operating mode, with different sendings of degraded modes 14, is thus implemented by the computer 3. A fault report signaling a vacuum supply failure for the after-sales service 16 is provided, for example via a GSM type interface, this being part of remote monitoring of the vehicle. A sending of a degraded mode requesting the activation of a malfunctioning periodic control mode 17 is provided, this giving the possibility of still having at least one braking allowing the driver to stop the vehicle. A STOP (or Service) indicator light informing the driver of a fault on his vehicle is provided, this alerting the driver without delay and forcing him to stop the vehicle.

[0039] The vacuum requirement, detected by the pressure sensor 6, controls the start-up of the electric vacuum pump 2, according to a lower continuous activation pressure threshold DPon and an upper continuous deactivation pressure threshold DPoff (see [Fig.2]). The upper continuous deactivation pressure threshold DPoff is higher than the lower continuous activation pressure threshold DPon. As soon as a target vacuum level is reached between DPon and DPoff, the electric vacuum pump 2 stops.

[0040] According to the present invention, the method 19 for controlling the electric vacuum pump 2 requires the introduction of two new activation and deactivation thresholds, namely a lower periodic activation pressure threshold DPon' and an upper periodic deactivation pressure threshold DPoff'. The activation and deactivation thresholds are positioned in the following order and must not overlap with each other: periodic deactivation pressure threshold DPoff', continuous deactivation threshold DPoff, continuous activation threshold DPon, and periodic activation pressure threshold DPon'. The upper periodic deactivation pressure threshold DPoff' is higher than the upper continuous deactivation pressure threshold DPoff. The upper continuous deactivation pressure threshold DPoff is higher than the lower continuous activation pressure threshold DPon.And the lower pressure threshold of continuous activation DPon is higher than the lower pressure threshold of periodic activation. DPon'.

[0041] As shown in [Fig. 3], and according to the present invention, the method 19 for controlling the electric vacuum pump 2 comprises two operating modes, namely a continuous operating mode and a periodic operating mode.

[0042] To obtain an activation of the periodic operating mode 21 of the vacuum pump 2, and thus a deactivation of the continuous operating mode of the vacuum pump 2, the cumulative conditions “AND” 22 are as follows.

[0043] As a first mandatory condition 23, the duration of continuous activation of the vacuum pump 2 must be greater than a first determined duration tl. For example tl > 30s. But also as an alternative criterion, the measured pressure DP must be greater than a lower continuous activation pressure threshold DPon and less than or equal to an upper continuous deactivation pressure threshold DPoff.

[0044] As a second mandatory condition 24, a vehicle speed V is lower than a threshold speed Vs. The vehicle threshold speed Vs must be low, for example V < 30km / h.

[0045] As a third mandatory condition 26, an altitude of the vehicle is between a minimum altitude Hmin and a maximum altitude Hmax. The altitude must for example be between 0 (Hmin) and 3000 m (Hmax).

[0046] As soon as the vacuum pump 2 switches from the continuous operating mode to the periodic operating mode 21, a countdown of the periodic activation timer 27 is activated.

[0047] To obtain a deactivation of the periodic operating mode 28 of the vacuum pump 2, and thus an activation of the continuous operating mode of the vacuum pump 2, only one of the following non-cumulative conditions “OR” 29 must be fulfilled.

[0048] In the first optional condition 31, the measured pressure DP may exceed or be equal to the upper periodic deactivation threshold DPoff': DP > DPoff'. In this case, the periodic mode and the continuous mode are stopped, the target depression threshold being reached.

[0049] In the second optional condition 32, the measured pressure DP may exceed the lower periodic deactivation threshold DPon': DP < DPon'. In this case, the control of the vacuum pump 2 then switches back to continuous activation.

[0050] In the third optional condition 33, the measured pressure DP may remain above the upper continuous deactivation pressure threshold DPoff, but may remain below the upper periodic deactivation threshold DPoff', for a time delay t2. For example t2 = 30s. After 30s, the periodic mode stops and the vacuum pump 2 will automatically stop because the pressure DP is above the upper continuous deactivation pressure threshold DPoff.

[0051] In the fourth optional condition 34, the measured pressure DP can remain below the lower continuous activation threshold DPon, but not below the lower periodic deactivation threshold DPon', for a time delay t3. For example t3 = 30s. After 30s, the periodic mode stops, the continuous mode is reactivated and the vacuum pump 2 will automatically restart in continuous mode because the pressure DP is below the lower continuous activation pressure threshold DPon.

[0052] Different measured pressure curves DP as well as the consequences on the control of the vacuum pump 2 are represented in Figs. 4a-4d. These curves correspond to situations which concern the conditions of activation and deactivation of the periodic mode. The activation of the functional periodic activation can only be done after having had a long continuous activation beforehand (of 30s or less), for all the cases which follow below.

[0053] If the driver ceases all contact with the brake and the measured pressure DP remains continuously between the lower continuous activation pressure threshold DPon and the upper continuous deactivation pressure threshold DPoff, the vacuum pump 2 is activated continuously for 15s. The measured pressure DP rises 36 and exceeds the lower continuous activation pressure threshold DPon, but remains below the upper continuous deactivation pressure threshold DPoff. Continuous activation remains until the 30s have elapsed, then the control switches to periodic mode, beyond the planned 20s, because the measured pressure DP remains below the upper continuous deactivation pressure threshold DPoff, until t=100s. The periodic mode is continuous and is maintained beyond the 20s. This corresponds to a lasting periodic activation.

[0054] The 20s time delay of the periodic mode is triggered 37, beyond the 15s continuously, but as the DP pressure remains blocked between the lower pressure thresholds for continuous activation DPon and upper pressure thresholds for continuous deactivation DPoff, the periodic activation continues beyond the time delay.

[0055] The measured pressure DP crosses the lower periodic deactivation threshold DPon'. The periodic activation then ceases and the control of the vacuum pump 2 switches back to continuous activation. In this case, the continuous activation lasts 40s non-stop, beyond the time delay because the measured pressure DP remains blocked below the lower periodic deactivation threshold DPon'.

[0056] The measured pressure DP rises, the control of the vacuum pump 2 returns to periodic activation between the lower pressure thresholds for continuous activation DPon and the upper pressure threshold for continuous deactivation DPoff, beyond the 20s of periodic activation planned.

[0057] When the lower periodic deactivation threshold DPon' is exceeded 41, the control of the vacuum pump 2 leaves the periodic activation for continuous activation.

[0058] If the driver immediately ceases all contact with the brake when starting the periodic mode, the control of vacuum pump 2 then exits periodic mode 42, before the planned 20s because the measured pressure DP will quickly be higher than the upper periodic deactivation threshold DPoff'.

[0059] The periodic activation 42 restarts for a brief instant, at the moment when the lower continuous activation pressure threshold DPon is crossed, because the measured pressure DP is in the zone between the upper continuous deactivation pressure threshold DPoff and the upper periodic deactivation threshold DPoff'. The periodic activation 42 stops at the moment when the upper periodic deactivation threshold DPoff' is exceeded.

[0060] When the measured pressure DP remains stable 43, the control does not cause activation of the vacuum pump 2, because the measured pressure DP is above the lower continuous activation pressure threshold DPon, therefore no activation of the continuous mode or activation of the periodic mode.

[0061] Continuous activation 44 is launched as soon as the lower continuous activation pressure threshold DPon is crossed, after 20s.

[0062] If the driver presses the brake pedal more lightly and the measured pressure DP rises above the upper continuous deactivation pressure threshold DPoff, but remains below the upper periodic deactivation threshold DPoff' during the time delay, after 20s the periodic mode stops 46. The control stops the activation of the electric vacuum pump 2. The measured pressure DP crosses the upper continuous deactivation pressure threshold DPoff. The periodic activation is triggered for 20s only, because the pressure is above the upper continuous deactivation pressure threshold DPoff. And since the measured pressure DP does not cross the upper periodic deactivation threshold DPoff', the vacuum pump 2 then cuts out after 20s.

[0063] Continuous activation 47 is launched as soon as the lower continuous activation pressure threshold DPon is crossed, after 20s.

[0064] If the driver presses the brake pedal more violently than before and the measured pressure DP falls below the lower continuous activation pressure threshold DPon, but not below the lower periodic deactivation threshold DPon' during the time delay, after 20s the periodic mode stops 48. At the start of this situation, the electric vacuum pump 2 is activated in the continuous operating mode. Continuous activation starts as soon as the lower continuous activation pressure threshold DPon is crossed and lasts 30s. After these 30s of continuous activation, the control of the vacuum pump 2 switches to periodic mode. The measured pressure DP remains blocked between the lower continuous activation pressure threshold DPon and the lower periodic deactivation threshold DPon'.

[0065] Towards the end of the previous braking situation, the periodic activation 49 then activates for 20s, but as the measured pressure DP remains blocked between the lower pressure threshold for continuous activation DPon and the lower threshold for periodic deactivation DPon', the control switches back to continuous activation.

[0066] If the driver makes insistent and repeated brake presses, the measured pressure DP falls below the lower periodic deactivation threshold DPon', before the 20s period, the control of the vacuum pump 2 leaves the periodic mode. The control switches back to a long activation of the vacuum pump 2. The periodic activation is triggered for a brief moment, at the moment when the lower continuous activation pressure threshold DPon is crossed. The measured pressure DP is in the zone between the lower continuous activation pressure threshold DPon and the lower periodic deactivation threshold DPon'. The control switches back to continuous activation as soon as the lower periodic deactivation threshold DPon' is crossed. In this situation 51, the periodic activation has priority over the continuous activation, over the 10s.

[0067] Various modifications and / or improvements may be made by those skilled in the art to the various embodiments of the invention described in the present description without departing from the scope of the invention. If the present invention has a relative pressure sensor, the sensor may also be an absolute pressure sensor. In this case, the activation-deactivation thresholds are therefore reversed compared to what has been previously described.

Claims

Claims

1. Method for controlling an electric vacuum pump (2) in a vacuum braking system for a vehicle, comprising the steps of: - measuring a pressure (DP) in the braking system, and - controlling the vacuum pump (2) according to a continuous operating mode or a periodic operating mode, the control of the vacuum pump (2) switching from the continuous operating mode to the periodic operating mode, and vice versa, at least as a function of the measured pressure (DP) in the braking system, when only one of the following conditions is met: - the measured pressure (DP) is greater than or equal to an upper pressure threshold for periodic deactivation (DPoff'), - the measured pressure (DP) is less than a lower pressure threshold for periodic activation (DPon'),- the measured pressure (DP) is greater than a continuous upper deactivation pressure threshold (DPoff) and less than the periodic upper deactivation pressure threshold (DPoff') for a second determined duration (t2), - the measured pressure (DP) is less than a continuous lower activation pressure threshold (DPon) and greater than a periodic lower activation pressure threshold (DPon') for a third determined duration (t3).,

2. Method according to claim 1, characterized in that the control of the vacuum pump (2) switches from the continuous operating mode to the periodic operating mode, when the following conditions are simultaneously fulfilled: - a continuous activation duration (t) of the vacuum pump (2) is greater than a first determined duration (tl), or the measured pressure (DP) is greater than a lower continuous activation pressure threshold (DPon) and less than or equal to an upper continuous deactivation pressure threshold (DPoff), - a vehicle speed (V) is less than a threshold speed (Vs), - a vehicle altitude is between a minimum altitude (Hmin) and a maximum altitude (Hmax).

3. Method according to claim 2, characterized in that the upper continuous deactivation pressure threshold (DPoff) is greater than the continuous activation lower pressure threshold (DPon).

4. Method according to one of the preceding claims, characterized in that the upper pressure threshold for periodic deactivation (DPoff') is greater than the upper pressure threshold for continuous deactivation (DPoff), in that the upper pressure threshold for continuous deactivation (DPoff) is greater than the lower pressure threshold for continuous activation (DPon), and in that the lower pressure threshold for continuous activation (DPon) is greater than the lower pressure threshold for periodic activation (DPon').

5. Method according to one of the preceding claims, characterized in that the control of the vacuum pump (2) remains in the periodic operating mode beyond a fourth determined duration, when the measured pressure (DP) is greater than a lower continuous activation pressure threshold (DPon) and less than or equal to an upper continuous deactivation pressure threshold (DPoff).

6. Method according to any one of the preceding claims, characterized in that it comprises an additional step, in the event of overheating or damage to the vacuum pump (2), following long continuous activation, consisting of activating at least one of the following degraded modes, with: - sending a signal to the after-sales service, signaling a failure of the vacuum pump (2), - activation of a malfunctioning periodic control mode of the vacuum pump (2), - lighting of a warning light on the dashboard, corresponding to a failure of the vehicle, - activation of a hydraulic pump of an electronic trajectory corrector (11).

7. Method according to any one of the preceding claims, characterized in that the control of the vacuum pump (2) is implemented using an engine computer of the vehicle (3).

8. A vacuum braking system for a vehicle, comprising an electric vacuum pump (2), the control of the vacuum pump (2) being carried out in accordance with the method according to any one of the preceding claims.

9. A motor vehicle comprising a braking system according to claim 8.

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