Braking process for a motor vehicle

Abstract

The motor vehicle comprises a main hydraulic braking circuit and an electromechanical auxiliary braking circuit, each configured to apply a braking member to a braking element. The method comprises the following steps: - detecting that the vehicle is parked, - when the motor vehicle is parked, applying a braking member to a braking element by means of the electromechanical auxiliary braking circuit, until a predetermined initial application force is obtained, - determining the slope (S) of the motor vehicle, - determining the temperature (T) of the braking element and / or the braking member,the braking method further comprising the following steps when the determined slope is greater than a predetermined value (S1) and / or when the determined temperature is greater than a predetermined value (T1): - selection from the main hydraulic braking circuit and the electromechanical auxiliary braking circuit, as a function of the determined value of the slope (S) and the determined value of the temperature (T), of the re-tightening circuit configured to perform a re-tightening of the braking member on the braking element, - selection of a number n of re-tightenings to be performed, n being a strictly positive integer predetermined and variable / configurable as a function of the determined value of the slope (S) and the determined value of the temperature. Figure for the abstract: figure 1,

Description

Title of the invention: Braking method for a motor vehicle

[0001] The invention relates to the field of motor vehicle braking.

[0002] A braking system for a motor vehicle is already known in the prior art, comprising, for example, a main hydraulic braking circuit and an auxiliary electromechanical braking circuit.

[0003] The main hydraulic braking circuit is for example controlled by an electronic control device, also called an electric brake amplifier or in English "Electric Brake Booster", making it possible to amplify the hydraulic braking pressure by facilitating the pressure to be exerted during a manual braking command by pressing a brake pedal, or during an automatic braking command from an electronic control unit or ECU. The hydraulic braking circuit controls hydraulic actuators of braking members, such as hydraulic pistons.

[0004] The electromechanical auxiliary braking circuit provides an electric parking brake function, or in English "Electric Parking Brake", and even preferably an automatic parking brake function. This electromechanical auxiliary braking circuit controls electric actuators of braking components. In the event of failure of the main hydraulic braking circuit, the electromechanical auxiliary braking circuit provides emergency dynamic braking - also called rolling braking.

[0005] The hydraulically and / or electrically actuated braking members are configured to brake the wheels of the motor vehicle. For this purpose, each braking member comprises, for example, a brake caliper comprising friction means, such as, for example, brake pads, which it drives towards braking elements each secured to a wheel of the vehicle, such as, for example, brake discs. For example, the electric parking brake function of the electromechanical auxiliary braking circuit is activated, respectively deactivated, by pressing an activation button.

[0006] Furthermore, the electronic control device is for example configured to control the main hydraulic braking circuit, not only to ensure the main hydraulic braking function of the motor vehicle, but also to ensure certain dynamic braking functions, such as the anti-lock braking function - also known by the acronym ABS for "Anti-lock Braking". kiersystem" in German - or electronic stability control for electronic trajectory control - also known by the acronym ESP for "Electronic Stability Program" in English or ESC for "Electronic Stability Control" in English.

[0007] In order to allow the motor vehicle to stop, the braking members apply an initial clamping force to the braking elements. However, due to the design of the braking members and the braking elements, the temperature thereof has an impact on the clamping force. For example, the coefficient of friction between the brake pads and the brake discs decreases during a cooling phase, which reduces the clamping force exerted. Thus, the clamping force may become insufficient to keep the motor vehicle stationary, and there is then a risk that the vehicle will start moving accidentally, for example when parked on a slope.

[0008] Thus, in order to ensure that the motor vehicle remains stationary, it is necessary in certain cases to carry out at least one re-tightening of the braking components in order to maintain the parking brake function. For example, when the estimated or measured temperature of the braking elements is below a predetermined threshold, such as 50°C: - when the vehicle is parked on a slope with no or slight gradient, for example less than 15%, no tightening is carried out, - when the motor vehicle is parked on an average slope, for example between 15 and 21%, three successive re-tightenings are carried out by the electromechanical auxiliary braking circuit, for example 3s, 30s and 300s after the motor vehicle has stopped, - when the motor vehicle is parked on a steep slope, for example greater than 21%, three successive tightenings are carried out by the main hydraulic braking circuit, for example 3s, 30s and 300s after the motor vehicle has stopped.

[0009] The following table shows an example of the three cases stated above depending on the slope and temperature of the braking elements. In this table: - category 1 corresponds to cases where no tightening is carried out, - category 2 corresponds to cases where three successive re-tightenings are carried out by the electromechanical auxiliary braking circuit, for example 3s, 30s and 300s after stopping the motor vehicle, and - category 3 corresponds to cases where three successive re-tightenings are carried out by the main hydraulic braking circuit, for example 3s, 30s and 300s after stopping the motor vehicle.

[0010] [Tables] Temperature (°C) Slope (%) 0-50 50-100 100-150 150-200 200-250 250-300 >300 0-4 1 1 1 1 1 1 3 4-6 1 1 1 1 1 2 3 6-8 1 1 1 1 2 2 3 8-10 1 1 1 2 2 2 3 10-12 1 1 2 2 2 2 3 12-13 1 2 2 2 2 2 3 13-15 1 2 2 3 3 3 3 15-21 2 2 2 3 3 3 3 >21 3 3 3 3 3 3 3

[0011] Even if these three cases make it possible to keep the motor vehicle stationary, such a re-tightening strategy is not optimal, because the braking members and the braking elements are in certain cases over-stressed with regard to the actual need for re-tightening. Thus in certain cases, a single re-tightening could be sufficient to keep the vehicle stationary, instead of three successive re-tightenings. There is therefore a need to optimize the re-tightening strategy, in order to increase the service life of the braking members and the braking elements, and to reduce energy consumption while allowing the motor vehicle to be kept stationary.

[0012] The aim of the invention is to provide a braking method for a motor vehicle making it possible to keep the motor vehicle stationary while providing an optimized tightening strategy.

[0013] To this end, the invention relates to a method for braking a motor vehicle comprising a main hydraulic braking circuit and an electromechanical auxiliary braking circuit, each configured to apply a braking member to a braking element, the method being configured to keep the vehicle stationary and comprising the following steps:

[0014] - vehicle parking detection,

[0015] - when the parking of the motor vehicle is detected, tightening of a member of braking on a braking element by means of the electromechanical auxiliary braking circuit, until a predetermined initial clamping force is obtained,

[0016] - determination of the slope of the motor vehicle,

[0017] - determination of the temperature of the braking element and / or the braking member braking,

[0018] the braking method further comprising the following steps when the determined slope is greater than a predetermined value (SI) and / or when the determined temperature is greater than a predetermined value (Tl):

[0019] - selection between the main hydraulic braking circuit and the auxiliary circuit electromechanical braking, depending on the determined value of the slope and the determined value of the temperature, of the tightening circuit configured to perform a tightening of the braking member on the braking element,

[0020] - selection of a number n of tightenings to be carried out, n being an integer strictly positive predetermined and variable depending on the determined value of the slope and the determined value of the temperature,

[0021] - for each tightening to be carried out, selection of a next tightening time obtaining the predetermined initial tightening force, each tightening moment being predetermined and variable depending on the determined value of the slope and the determined value of the temperature,

[0022] - carry out n tightenings of the braking member on the braking element by the selected tightening circuit, each tightening being carried out at a predetermined tightening time until a predetermined tightening force is obtained.

[0023] Thus, the number of re-tightenings to be carried out varies according to the determined value of the slope and / or according to the determined value of the temperature, which makes it possible to optimize the re-tightenings. It is thus possible to avoid over-stressing the braking members and the braking elements while ensuring the immobility of the vehicle, in particular when the vehicle is parked on a zero slope or a slight slope with a slight inclination. In other words, it is proposed to carry out a number of re-tightenings adapted according to the slope and / or the temperature, sufficient to immobilize the vehicle but not more than necessary.

[0024] The steps of determining the vehicle slope and the temperature make it possible to determine whether re-tightening is required, and if so to choose a required re-tightening category to prevent the vehicle from accidentally starting to move. Preferably, a re-tightening category defines the circuit providing the re-tightening (among the main hydraulic braking circuit and the electromechanical auxiliary braking circuit), and a number of re-tightenings to be carried out, each being associated with a given time after activation of parking.

[0025] In the proposed invention, the number of tightenings to be carried out is advantageously variable depending on the category chosen, because it depends on the determined value of the slope and the determined value of the temperature. Thus, advantageously:

[0026] - on a zero or low slope, no or only one tightening is carried out,

[0027] - on an average slope, two or three successive tightenings are carried out, and

[0028] - on a steep slope, three or four successive tightenings are carried out.

[0029]

[0030] The braking method may further comprise one or more of the following optional features, taken alone or in combination.

[0031] - The brake member is a brake caliper.

[0032] - The brake element is configured to be secured to a wheel of the vehicle. so that the wheel can be clamped after parking has been activated. The brake element is in particular a brake disc.

[0033] - The step of detecting the parking of the vehicle is carried out by detecting pressing an activation button, the activation button preferably being a button for activating the electric parking brake function of the electromechanical auxiliary braking circuit. Such activation is generally detectable after intervention by the driver, for example by manually pressing the button. It is understood that, preferably, it is the electromechanical auxiliary braking circuit which ensures the parking of the vehicle, by exerting a predetermined initial clamping force.

[0034] - The step of determining the slope of the motor vehicle is carried out by the measurement of the slope of the motor vehicle by a tilt sensor.

[0035] - The value of the determined slope is an absolute value.

[0036] - The predetermined value (SI) of the slope triggering at least one tightening is a value between 0% and 15%. This predetermined value (SI) is preferably between 12 and 18%, for example close to 15%, for a given temperature close to 0°C.

[0037] - The step of determining the temperature of the braking element and / or the braking member is carried out by estimation based on a braking command applied by a driver of the motor vehicle to the main hydraulic braking circuit. More precisely, the temperature is estimated from the hydraulic pressure applied by the driver, by converting the applied kinetic energy into heat energy. Alternatively or in combination, the step of determining the temperature of the braking element and / or the braking member is carried out by a temperature sensor, which is arranged close to the wheels. In general, such sensors are used in the field of vehicles adapted for motor racing.

[0038] - The predetermined value (Tl) of the temperature triggering at least one tightening is a value between 0°C and 350°C. For a given slope close to 0%, this predetermined value (Tl) is preferably between 250°C and 350°C, for example close to 300°C.

[0039] - The method comprises the following step: when the determined slope of the slope is lower than the predetermined value (SI) and when the determined temperature of the temperature is lower than the predetermined value (Tl), maintaining unchanged the tightening of the braking member on the braking element.

[0040] It is understood that in this step no re-tightening is carried out by the braking member. Advantageously, this step of the braking method ensures that no unnecessary re-tightening is carried out when the vehicle is on a zero or very slight slope and that the vehicle can be kept stationary solely by the clamping circuit, preferably the electromechanical auxiliary braking circuit when it is parked.

[0041] - The number n of tightenings to be carried out is between 1 and 20, preferably se selected from 1, 2, 3, 4, 5. In other words, the braking method allows to carry out, depending on the temperature and the slope determined, between 1 and 20 re-tightenings, advantageously between 1 and 5 re-tightenings. For example, on an average slope, between 15% and 21%, preferably a single re-tightening is carried out in the case of a temperature close to 0°C, or three successive re-tightenings are carried out in the case of a temperature between 150°C and 300°C. According to another example on a higher slope, greater than 21%, preferably two successive re-tightenings are carried out in the case of a temperature close to 0°C, or four successive re-tightenings are carried out in the case of a temperature above 200°C.

[0042] - Each predetermined instant is selected in an interval of 1s (seconds) to 3600s, following the achievement of the predetermined initial tightening force, preferably in an interval of 2s to 600s, more preferably of 2s to 400s. It is understood here that after the detection of parking, for example by pressing an activation button, the tightening begins when the driver is present in the vehicle, and depending on the level of tightening required, this tightening continues, for example even when the driver has left the vehicle. It is understood that the presence of the driver in the vehicle is not necessary to ensure the safe maintenance of the vehicle at a standstill, in particular on a slope.

[0043] - When the determined slope is greater than 21%: the tightening circuit selected is the main hydraulic braking circuit, the number n being equal to 2 when the determined temperature is lower than 200 °C and the number n being equal to 4 when the determined temperature is higher than 200 °C. It is understood that such a setting is suitable for a vehicle parked on a steep slope. In general, under the effect of a high temperature, a greater number of retightenings is required, in particular because the coefficient of friction between the braking elements and the braking components decreases during the cooling phase, which tends to reduce the clamping force exerted by the main circuit.

[0044] - When the determined slope is between 15% and 21%: * the selected tightening circuit is the electromechanical auxiliary circuit of braking when the determined temperature is below 300°C, the number n being equal to 1 when the determined temperature is below 150°C and the number n being equal to 3 when the temperature is between 150°C and 300°C, and * the selected tightening circuit is the main hydraulic braking circuit when the determined temperature is greater than 300°C, the number n being equal to 4. It is understood that such a setting is suitable for a vehicle which is placed on an average slope.

[0045] - When the determined temperature is greater than 300°C: the tightening circuit selected is the main hydraulic braking circuit, the number n being equal to 3 when the determined slope is between 0% and 8% and the number n being equal to 4 when the determined slope is greater than 8%. It is understood here that under conditions of high temperature, the number of required re-tightenings is generally also high, even if the vehicle is placed on a slope with a very slight inclination, for example between 0% and 8%.

[0046] - When the determined temperature is between 150°C and 200°C:

[0047] * the selected tightening circuit is the electromechanical auxiliary circuit of braking when the slope is between 8% and 21%, the number n being equal to 3, and * the selected tightening circuit is the main hydraulic braking circuit when the determined slope is greater than 21%, the number n being equal to 2.

[0048] - When the determined temperature is between 100°C and 150°C:

[0049] * the selected tightening circuit is the electromechanical auxiliary circuit of braking when the slope is between 10% and 21%, the number n being equal to 1, and * the selected tightening circuit is the main hydraulic braking circuit when the determined slope is greater than 21%, the number n being equal to 2.

[0050] - When the selected tightening circuit is the electro auxiliary circuit braking mechanics:

[0051] * when the number n is equal to 1, the predetermined time is 50s,

[0052] * when the number n is equal to 3, the predetermined times are 3s, 30s and 300s; And when the selected tightening circuit is the main hydraulic brake circuit: * when the number n is equal to 2, the predetermined instants are 10s and 600s or 5s and 120s,

[0053] * when the number n is equal to 4, the predetermined instants are 2s, 25s, 80s and 400s.

[0054] It is understood that the predetermined time for carrying out the tightenings is advantageously variable depending on the tightening circuit selected. The main hydraulic braking circuit and the electromechanical auxiliary circuit have forces of different tightenings. Therefore, when one or the other is selected by the braking process to perform a re-tightening, the selection is generally also made on the basis of the force that can be provided by each circuit before being able to assess the optimal number of re-tightenings that are required and at what time they should be performed. Brief description of the figures

[0055] 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:

[0056] [Fig.l] is a diagram illustrating a method of braking a motor vehicle according to the invention. Detailed description

[0057] Illustrated in [Fig.l] is the braking method 100 of a motor vehicle comprising steps for determining whether re-tightening is necessary to keep the vehicle stationary.

[0058] Such a method 100 is suitable for motor vehicles comprising a braking device acting at a wheel of the vehicle. The braking device generally comprises a braking member and a braking element. Preferably, the braking element is a brake disc fixed to an axle of the vehicle, and the braking member is a brake caliper which comprises friction means, preferably brake pads intended to clamp the brake disc during braking.

[0059] The braking device is advantageously actuated by a braking circuit which is itself controlled by a control unit or ECU. Generally, the vehicle comprises a main hydraulic braking circuit and an electromechanical auxiliary braking circuit.

[0060] The main hydraulic braking circuit is controlled by an electronic control device, also called an electric brake amplifier (or in English "Electric Brake Booster"), making it possible to actuate the braking device when a manual instruction is requested by a driver, for example by pressing a brake pedal, or during an automatic braking instruction, from the electronic control unit (ECU).The electronic control device is also configured to control the main hydraulic braking circuit in certain dynamic braking functions, such as the anti-lock braking function - also known by the acronym ABS for "Antiblo-kiersystem" in German - or electronic stability control for electronic trajectory control - also known by the acronym ESP for "Electronic Stability Program" in English or ESC for "Electronic Stability Control" in English.

[0061] The electromechanical auxiliary braking circuit generally provides an electric parking brake function (or in English "Electric Parking Brake"), or even an automatic parking brake function (in English "Automatic Parking Brake"). Such an auxiliary circuit controls electric actuators of braking components. In the event of failure of the main hydraulic braking circuit, the electromechanical auxiliary braking circuit provides emergency dynamic braking - also called rolling braking.

[0062] According to the embodiment illustrated in [Fig. 1], the braking method 100 provides the following steps:

[0063] - a step 10 of activating the parking of the vehicle. Such activation is carried out by pressing an activation button, the activation button is preferably an activation button for the electric parking brake function of the electromechanical auxiliary braking circuit.

[0064] - A step 20 of detecting a vehicle parking instruction. By For example, a parking instruction corresponds to a signal sent to the control unit or ECU of the motor vehicle, such as a signal carrying a number 1 meaning that a parking instruction has been requested by the driver.

[0065] - A step 30 of testing the applied clamping force, preferably corresponding to the clamping of the braking member on the braking element by means of the electromechanical auxiliary braking circuit. During step 30, the braking member bears against the brake element until a predetermined initial clamping force is obtained to keep the vehicle stable. If such a clamping force is not reached, the method provides a step 40 of return to the control unit which again controls the clamping of the braking member on the braking element to ensure the safety of the parked vehicle. If the predetermined initial clamping force is reached, the process proceeds to a step 50.

[0066] Step 50 is a step of determining the slope S of the motor vehicle and the temperature T of the braking element and / or the braking member. This step provides for determining the value of the slope S on which the vehicle is positioned, preferably by means of an inclination sensor present on the vehicle. Step 50 also provides for determining the temperature T of the braking member and / or the braking element by an estimation from the hydraulic pressure applied by the driver.This step 50 also makes it possible to compare these determined values ​​S, T with predetermined threshold values ​​of slope and temperature, in particular with a predetermined value of the slope SI and a predetermined value of temperature TL. In this example, the predetermined value of the slope SI is an absolute value which is between 12% and 18%, more precisely close to 15%; and the predetermined value of the temperature Tl is between 250°C and 350°C, for example. example close to 300°C. These predetermined values ​​SI and Tl correspond here to the conditions where retightening is not required by the vehicle.

[0067] When the determined value of the slope S is greater than the predetermined value of the slope S1 and / or when the determined value of the temperature T is greater than the predetermined value T1, the method 100 continues with a re-tightening step 60 in which an optimal braking circuit is selected from the main hydraulic braking circuit and the electromechanical auxiliary braking circuit as a function of the value of the determined slope S and the value of the determined temperature T. Then an optimal number n of re-tightenings is selected followed by a time tn to carry out each re-tightening. More precisely, step 60 consists of choosing a re-tightening category from several parameterized categories, to prevent the vehicle from accidentally starting to move.The re-tightening category defines the circuit performing the re-tightening among the main hydraulic braking circuit and the electromechanical auxiliary braking circuit, and a number of re-tightenings to be performed, each associated with a given time after the activation of parking. In this example, five re-tightening categories are considered, described below.

[0068] The braking method 100 further provides a step 70 for ending without re-tightening when the determined slope S is less than the predetermined value S1 and when the determined temperature T is less than the predetermined value TL. This step 70 makes it possible to maintain the tightening of the braking member on the braking element unchanged. The vehicle conditions do not require re-tightening and the electromagnetic auxiliary circuit alone is generally capable of keeping the motor vehicle stationary.

[0069] The number n of tightenings to be carried out according to the tightening categories is selected from 1 and 20, preferably from 1, 2, 3, 4, 5.

[0070] For each n tightening to be carried out, a tightening time tn is selected according to the initial tightening force. Each tightening time tn is predetermined and variable according to the determined value of the slope S and the determined value of the temperature T. Thus a number n of tightenings is carried out by a selected tightening circuit, each n tightening being carried out at a predetermined tightening time tn until a predetermined tightening force is obtained.

[0071] Each predetermined instant tn is selected in an interval of 1s to 3600s, preferably of 2s to 600s, more preferably 2s to 400s, depending on obtaining the predetermined initial clamping force.

[0072] When the vehicle is positioned on a steep slope, the electromechanical auxiliary braking circuit is generally selected to perform the re-tightening. Under high temperature conditions, the re-tightening is generally performed by the main hydraulic braking circuit. The re-tightening is performed by one or other of the braking circuits under conditions of average temperatures and / or average inclinations.

[0073] The following table shows the categories stated above as a function of the determined slope S and the determined temperature T of the braking elements.

[0074] [Tables2] Temperature (°C) Slope (%) 0-50 50-100 100-150 150-200 200-250 250-300 >300 0-4 1 1 1 1 1 1 4 4-6 1 1 1 1 1 4 4 6-8 1 1 1 1 4 4 4 8-10 1 1 1 4 4 4 5 10-12 1 1 2 4 4 4 5 12-13 1 2 2 4 4 4 5 13-15 1 2 2 4 4 4 5 15-21 2 2 2 4 4 4 5 >21 3 3 3 3 5 5 5

[0075] In this table: - category 1 corresponds to cases where no tightening is carried out, - category 2 corresponds to cases where a tightening is carried out by the electromechanical auxiliary braking circuit, for example 50s after stopping the motor vehicle, - category 3 corresponds to cases where two successive re-tightenings are carried out by the main hydraulic braking circuit, for example 50s and 120s after stopping the motor vehicle, - category 4 corresponds to cases where three successive re-tightenings are carried out by the electromechanical auxiliary braking circuit, for example 3s, 30s and 300s after stopping the motor vehicle, and - category 5 corresponds to cases where four successive re-tightenings are carried out by the main hydraulic braking circuit, for example 2s, 25s, 80s and 400s after stopping the motor vehicle.

[0076] Thus, when the determined slope S is greater than 21%, the selected tightening circuit is preferably the main hydraulic braking circuit. Under these steep slope S conditions, the number n is equal to 2 when the determined temperature T is less than 200°C and the number n is equal to 4 when the determined temperature T is greater than 200°C.

[0077] When the determined slope S is between 15% and 21%, that is to say in medium slope conditions, the selected tightening circuit is the electromechanical auxiliary braking circuit when the determined temperature T is less than 300 °C. The number n is equal to 1 when the determined temperature T is less than 150 °C and the number n is equal to 3 when the determined temperature T is between 150 °C and 300 °C. Under these same slope conditions S, i.e. in conditions of medium slope between 15% and 21%, the selected tightening circuit is the main hydraulic braking circuit when the determined temperature T is greater than 300 °C, the number n is equal to 4.

[0078] When the determined temperature T is greater than 300°C, the selected tightening circuit is the main hydraulic braking circuit. The number n is equal to 3 when the determined slope S is between 0% and 8% and the number n is equal to 4 when the determined slope S is greater than 8%.

[0079] When the determined temperature T is between 150°C and 200°C, the selected tightening circuit is the electromechanical auxiliary braking circuit when the slope S is between 8% and 21%. Under these conditions of generally average temperature T and average slope S, the number n is preferably equal to 3 or 4. Under the same average temperature conditions, the selected tightening circuit is the main hydraulic braking circuit when the determined slope S is greater than 21%. Under the conditions of average temperature T and steep slope S, the number n is preferably equal to 2 or 3.

[0080] When the determined temperature T is between 100°C and 150°C: - the selected tightening circuit is the electromechanical auxiliary braking circuit when the slope S is between 10% and 21%, the number n being equal to 1, and - the selected tightening circuit is the main hydraulic braking circuit when the determined slope S is greater than 21%, the number n being equal to 2.

[0081] When the selected tightening circuit is the electromechanical auxiliary braking circuit: - when the number n is equal to 1, the predetermined instant tn is 50s,

[0082] - when the number n is equal to 3, the predetermined instants tn are 3s, 30s and 300s. Furthermore, when the selected tightening circuit is the main hydraulic braking circuit:

[0083] - when the number n is equal to 2, the predetermined instants tn are 10s and 600s or of 5s and 120s,

[0084] - when the number n is equal to 4, the predetermined instants are 2s, 25s, 80s and 400s.

[0085] The invention is not limited to the embodiments presented and other embodiments will become clear to those skilled in the art. It is in particular possible to provide a greater number of re-tightenings to ensure that the vehicle is held on steep slopes, for example greater than 21%, and / or at high temperatures, for example greater than 300°C. It may be provided that on steep slopes, for example greater than 21%, without temperature concerns, the selected re-tightening circuit is the electromechanical auxiliary braking circuit. In the same way, it may be provided that for high temperatures, for example greater than 300°C, without slope concerns, the selected re-tightening circuit is the electromechanical auxiliary braking circuit. List of references

[0086] 100: Braking method, 10: vehicle parking activation step, 20: step of detecting a vehicle parking instruction,

[0087] 30: step of carrying out parking,

[0088] 40: step of returning to the control unit,

[0089] 50: step of evaluating the slope of the vehicle and the temperature of the element of braking and / or the braking component.

[0090] 60: tightening step

[0091] 70: end step without tightening

Claims

1. Claims Braking method (100) of a motor vehicle comprising a main hydraulic braking circuit and an electromechanical auxiliary braking circuit, each configured to apply a braking member to a braking element, the braking method being configured to keep the vehicle stationary and comprising the following steps: - vehicle parking detection, - when the parking of the motor vehicle is detected, application of a braking device to a braking element by means of the electromechanical auxiliary braking circuit, until a predetermined initial application force is obtained, - determination of the slope (S) of the motor vehicle, - determination of the temperature (T) of the braking element and / or of the braking member, the braking method further comprising the following steps when the determined slope is greater than a predetermined value (SI) and / or when the determined temperature is greater than a predetermined value (Tl): - selection from the main hydraulic braking circuit and the electromechanical auxiliary braking circuit, as a function of the determined value of the slope (S) and the determined value of the temperature (T), of the re-tightening circuit configured to perform a re-tightening of the braking member on the braking element, - selection of a number n of re-tightenings to be performed, n being a strictly positive whole number predetermined and variable as a function of the determined value of the slope (S) and the determined value of the temperature, - for each n tightening to be carried out, selection of a tightening time (tn) following the obtaining of the predetermined initial tightening force, each tightening time (tn) being predetermined and variable according to the determined value of the slope (S) and the determined value of the temperature (T), - carry out n; re-tightenings of the braking member on the braking element by the selected re-tightening circuit, each n re-tightening being carried out at a predetermined re-tightening time (tn) until a predetermined re-tightening force is obtained.

2. Braking method (100) according to the preceding claim, which comprises the following step: - when the determined slope (S) is less than the predetermined value (SI) and when the determined temperature (T) is less than a predetermined value (Tl), maintaining unchanged the clamping of the braking member on the braking element.

3. Braking method (100) according to any one of the preceding claims, wherein the number n is between 1 and 20, preferably selected from 1, 2, 3, 4, 5.

4. Braking method (100) according to any one of the preceding claims, wherein each predetermined instant (tn) is selected in an interval of 1s to 3600s following the obtaining of the predetermined initial clamping force, preferably in an interval of 2s to 600s, more preferably of 2s to 400s.

5. Braking method (100) according to any one of the preceding claims, wherein, when the determined slope (S) is greater than 21%: - the selected tightening circuit is the main hydraulic braking circuit, the number n being equal to 2 when the determined temperature (T) is less than 200°C and the number n being equal to 4 when the determined temperature (T) is greater than 200°C.

6. Braking method (100) according to any one of the preceding claims, wherein, when the determined slope (S) is between 15% and 21%: - the selected tightening circuit is the electromechanical auxiliary braking circuit when the determined temperature (T) is less than 300°C, the number n being equal to 1 when the determined temperature (T) is less than 150°C and the number n being equal to 3 when the determined temperature (T) is between 150°C and 300°C, and - the selected tightening circuit is the main hydraulic braking circuit when the determined temperature (T) is greater than 300°C, the number n being equal to 4.

7. Braking method (100) according to any one of the preceding claims, wherein, when the determined temperature (T) is greater than 300°C: - the selected tightening circuit is the main hydraulic braking circuit, the number n being equal to 3 when the determined slope (S) is between 0% and 8% and the number n being equal to 4 when the determined slope (S) is greater than 8%.

8. Braking method (100) according to any one of the preceding claims, wherein, when the determined temperature (T) is between 150°C and 200°C: - the selected tightening circuit is the electromechanical auxiliary braking circuit when the slope (S) is between 8% and 21%, the number n being equal to 3, and - the selected tightening circuit is the main hydraulic braking circuit when the determined slope (S) is greater than 21%, the number n being equal to 2.

9. Braking method (100) according to any one of the preceding claims, wherein, when the determined temperature (T) is between 100°C and 150°C: - the selected tightening circuit is the electromechanical auxiliary braking circuit when the slope (S) is between 10% and 21%, the number n being equal to 1, and - the selected tightening circuit is the main hydraulic braking circuit when the determined slope (S) is greater than 21%, the number n being equal to 2.

10. Braking method (100) according to any one of the preceding claims, wherein: when the selected tightening circuit is the electromechanical auxiliary braking circuit: - when the number n is equal to 1, the predetermined time (tn) is 50s, - when the number n is equal to 3, the predetermined times (tn) are 3s, 30s and 300s; and when the selected tightening circuit is the main hydraulic braking circuit: - when the number n is equal to 2, the predetermined times (tn) are 10s and 600s or 5s and 120s, - when the number n is equal to 4, the predetermined times are 2s, 25s, 80s and 400s.

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