FR3052726A1 - METHOD FOR ADAPTING THE TAKE-OFF OF A MOTOR VEHICLE - Google Patents

Abstract

Method for adapting the take-off of a motor vehicle with a heat engine and an automated transmission, comprising a step of determining take-off conditions (330), then an adaptation of the gear ratio (370) to be used for take-off as a function of the conditions , the determining step taking into account at least one parameter among the altitude (210), the consumption of auxiliary energy consumers of the vehicle (230) or the engine air intake temperature (200).

Description

The invention relates to motor vehicles comprising a powertrain (GMP) with a heat engine and equipped with an automated transmission.

[0002] Automated transmissions are experiencing a significant resurgence of interest. Although they are almost unanimous in some parts of the world (North America, Japan), they are experiencing rapid and significant development in others (Europe, China). There are several types, among which are mainly: [0003] - manual manual or robotic gearboxes (BVMP). It is a manual gearbox (BVM) whose clutch release, selection and clutch controls in particular, have been automated; - Double clutch gearboxes (DCT: dual clutch transmission). Such a gearbox is actually made up of two traditional half-gear boxes with parallel gears: the first half-box consists of odd reports while the second uses even reports. These two half-boxes are each controlled by a clutch, one for even reports and one for odd reports. The assembly thus achieves a double clutch transmission that can change gear without breaking torque by permutation of the clutches. As the engine spreads power on one gear, the next is preselected. The change of gear is performed under load without interrupting the traction force, by switching from one clutch to another as in BVA: the disengagement of a gear is performed simultaneously with the clutch of the other; [0005] Automatic gearboxes with a hydrodynamic torque converter (BVA). They consist of epicyclic gear trains, parts of which are secured by clutches or brakes to achieve different gear ratios. They also include a hydrodynamic or hydrokinetic torque converter installed immediately at the output of the engine. It replaces the mechanical clutch while being able to achieve a reduction. It is a toric and concentric member filled with oil and whose torus is divided into three parts: an impeller (or pump) integral with the crankshaft of the heat engine, a turbine integral with the primary shaft of the gearbox and a reactor (or stator). The impeller centrifuge the oil against the vanes of the turbine. The latter turns slower than the pump, because of the inclination of the blades, the oil flow returns to the impeller through the reactor which redirects it in the direction of rotation. The torque converter thus achieves a self-regulating variator capable of multiplying 2 to 2.5 times the motor torque. The efficiency of the torque converter being relatively low, the reactor is generally mounted on a freewheel with non-return ratchet to allow its free rotation, but only in the direction of the motor shaft, when the gear ratio reaches a certain value. Therefore, the said reactor becomes inactive and the converter operates as a coupler with a yield increasing to 97% - 98% at rated speed. All BVAs are nevertheless equipped with a bridging clutch (lock-up) which secures the impeller and the turbine when the converter is not needed. The turbine being secured to the motor shaft, the transmission is then only fully mechanical, eliminating losses by heat dissipation in the oil and thus greatly improving the efficiency of the transmission; [0006] Gearboxes with continuously variable transmission (GVT: continuousiy variable transmission). Unlike other transmissions that have a finite number of discrete gear ratios, a GVT adopts two variable diameter pulleys between which evolves a chain or a metal belt. The diameter of the pulleys can vary continuously and gradually, the transmission ratio also: the engine speed and torque applied are continuously adapted and no jerk is noticeable.

[0007] The economic and competitive pressure, in particular the price of fuels and the purchase of the vehicle and the costs of use and maintenance, and the environmental context, in particular the regulation of pollutant emissions, greenhouse gases and external sound level, guide the development of automated GMP, that is to say equipped with automated transmissions as described above, to the increase: [0008] - of the opening (ratio between the first gear ratios and last reports) of the gearbox: from a value of less than 2 in the 1940s, through 3 to 4 in the 1990s and 5 to 6 in the 2000s, up to 7 to 10 today ; - and (except obviously in the case of a GVT) the number of gear ratios or speeds: since 2 speeds in the 1940s, through 4 reports in the 1990s and up to 6 to 10 today Today, truck and heavy goods vehicles have much more to show.

These orientations are intended to reduce the average rotational speed of the engine to use, making it possible as often as possible to operate in its maximum yield area and, more particularly, to lower the engine speed for driving road and motorway with stabilized speed via the choice of the reduction of the last (or last two) reports of a transmission. In this, an open BVMP, DCT or BVA and a number of increased ratios tend to approach the operation of a CVT. Thus, industrial constraints (optimization of transmission manufacturing lines, reduction of diversity, etc.) guide manufacturers or equipment manufacturers transmission manufacturers and automakers to replace a generation of transmission by a generation with openness and number increased reports.

Such an orientation is however not ideal for the entire range of vehicles of a car manufacturer: an opening and a number of high ratios suitable for private vehicles (VP) of ranges B1, B2 or C is not always optimal, with the same thermal engine, for D-SUV or H series VPs or commercial vehicles (VU). The adaptation of the GMP to this type of vehicle, also equipped with large tires (developed, tread width, sidewall height, rim diameter), is subject to the industrial constraint of limiting the diversity of vehicles. transmissions, for example by adopting the same gear ratios internal to the gearbox or, in the case of a BVA, by limiting the diversity of torque converters. The adaptation of the GMP to this type of vehicle is then restricted to choosing the bridge from a limited range available for the same reasons of limitation of diversity.

In some cases, for the same range of heat engines not specifically developed to be coupled to a particular type of transmission and vehicle, the transmission is too open to meet the torque reserve criteria to provide a capacity of sufficient acceleration to the vehicle at high speed (90 to 130 km / h) and robustness of the last gear engaged. These last ratios are too long (that is to say, generate a vehicle speed at an engine speed of 1000 revolutions / min - vlOOO - too high) and are then accessible in a robust way only on rolling at constant speed on the flat only, and require the transition to the lower ratios of the slightest need to accelerate a little bit or the appearance of the slightest uphill slope, and may be inaccessible if the vehicle is more loaded than usual ( number of passengers, loading the boot, etc.).

By way of example, the application of the "very economic" acceleration reserve criterion to all BV gear changes of a given vehicle application, in order to provide a sufficient reserve of acceleration, prevents pass the last reports if the gear ratios or vLOOO associated are too long, thus depriving the vehicle of a possible gain in consumption. Thus, a decrease in the severity of this constraint provides access to additional consumption gains. The associated gearing is then typed "over-drive" and favors the consumption of the vehicle at the expense of its ability to acceleration and recovery: the least coast requires switching to lower BV report to find sufficient acceleration.

In the example of an eight-speed BVA coupled to a heat engine, the assembly forming the GMP of a given vehicle, one is interested in the typing qualification of eight reports. The wheel forces necessary to advance the vehicle to the desired speed in different conditions (flat, sloping) include the vehicle mass, the aerodynamic resistance it exerts on the air (SCx) and the different resistive efforts of friction (pneumatic, etc.), flat or sloping, for a given dynamic typing. The wheel power curves available for each gear ratio depend on the performance of the engine (static and dynamic torque as a function of the engine speed), the internal reduction of the gearbox, its opening, the gear ratio and the gear ratio. that developed from the tires of the vehicle.

With these constraints, if for example the 6th report remains dynamic (intersections of the characteristic of 6th for vehicle speeds of 90, 110 and 130 km / h are placed above the reserve curve associated with the dynamic typing), the 7th report is in this same example typed super-economic, normal and dynamic respectively at 90, 110 and 130 km / h, while the Sth and last report is out of the limit rollability at 90km / h, just rollable at 110km / h and typed super-economical at 130km / h. With these constraints (in particular the coast-down of the vehicle and the vlOOO of the report considered), it is not possible to climb a slope of 4% in Seme to less than 135km / h: a rolling of this type, for example on motorway with a continuous slope of 4%, while the vehicle is loaded (for example half payload), requires to go down to the 7th gear if previously the vehicle rolled in Seventh (for example if the highway was previously flat).

In some cases the motor adaptation - BV is just right, without margin, to the characteristics of the vehicle. In some cases where it is unsuitable, this adaptation results in a typing of last reports (the last report, or even the penultimate report partially) beyond rolling limit. This adaptation is then characterized by either: [0017] a tire of unsuitable dimensions: a lower developed reduces the vlOOO of all gear ratios by a ratio proportional to that of the developed ones; - and / or engine performance too low, unsuited to the vehicle: the torque and the power delivered by the engine are insufficient to meet the acceleration reserve criteria at vehicle speeds required engine speed imposed by the vlOOO ; [0019] - and / or a bridge that is too long: here again the vlOOO of the gear ratios are reduced proportionally to that of the bridges in the case of the adoption of a shorter bridge, which may not be possible with industrial constraints to reduce diversity when using the shortest bridge of a BV range or if the adoption of a shorter bridge of another BV range is not possible for holding reasons BV mechanical or internal BV implantation; [0020] and / or a BV that is too open: the bridge to be adopted must satisfy at least the constraints of a vlOOO of last maximum ratio in order to satisfy the criteria of rolling ability and acceleration reserve in this respect and of a vlOOO of the first optimum ratio (not too high or too low) to ensure the take-off of the vehicle in all conditions: [0021] - under minimum slopes according to the load of the vehicle (example: towing), [0022] - under load (total mass permitted under load, permissible total rolling mass), [0023] - under stress of absence of engine stall and of non-recoil of the vehicle, [0024] - under minimum vehicle speed criterion after 1 to 3 seconds after take-off.

- Sub criterion of mechanical and thermal coupling strength, especially in the case, for a BVA, a torque converter assuring the takeoff of the vehicle in out-of-tension mode, energy dissipated in the clutch of a DCT, [ 0026] - under ramping speed constraints (automatic transmission in "Drive" position and idling engine speed), in order to avoid having to increase the engine speed at idle and suffer the associated disadvantages (acoustics, fuel consumption), [0027] ] - under approval criterion of the passage 1 => 2 to come: engine revs, availability of engine torque at low revs, [0028] - under criterion of vehicle rolling ability in 2nd gear after passing 1 => 2, both in heavy load (in some life situations such as low-speed lane monitoring, a minimum throttle reserve is required at the lowest vehicle speeds without having to downgrade to 1st gear) than low (engine speed s using 2nd in the immediate outcome of passage 1 => 2).

If a choice is then possible, it must be done for a fixed BV opening too high, between: [0030] - the one proposing a last reports vlOOO (or equivalent criterion, in the case of a CVT) acceptable (even typing over-drive the last report, the penultimate one being sufficiently robust to satisfy a criterion of acceleration reserve at least super-economic without falling into the limitability category) but then a vlOOO of 1st report too much small (for example less than 5km / h at 1000 rev / min) to satisfy all the services associated with the take-off of the vehicle in all life situations; - On the contrary proposing a vlOOO last report out of limit rollability, or typed beyond the over-drive (or in the case of a CVT, realizing an acceleration reserve lower than the robustness criteria of the gearing in progress) to meet the expected criteria of a vlOOO 1st report.

Furthermore, it is known that the performance of so-called supercharged internal combustion engines, supercharged or not, commonly given under favorable conditions of temperature and pressure at the inlet of their combustion chambers, undergo severe damage as these conditions become more severe, both in engine inlet temperature and in pressure (a consequence of a high altitude). Consequently, in a context of vehicle take-off from a stationary state, in these difficult conditions (temperature and / or altitude), it seems virtuous to rapidly increase the engine speed in order to increase the available torque. A very short ratio of the 1st report, or even the 2nd report, allows in difficult conditions (temperature and / or altitude, steep slope, loaded vehicle, etc.) to quickly raise the engine speed. However, it is not possible to make a compromise between a take-off in a difficult situation, a take-off in a nominal situation (for example on the flat, by a mild temperature, at sea level, unladen vehicle), the consumption and pollutant emissions both regulatory and real.

[0033] JP2005106164 discloses an automatic transmission for a vehicle with a device for selecting a starting speed range in an automatic transmission. Nevertheless, many aspects of significant living conditions are not taken into account.

In this context, it is proposed that after the detection of an upcoming take-off of the vehicle, quickly discriminated to distinguish a takeoff in difficult and exceptional conditions, or in unsolicited and usual conditions, it is chosen to take off with a adequate report, in particular by allowing the direct selection of the 2nd report without first going through the 1st.

Being imposed an excessive opening of the automated transmission, it is proposed to choose a gear ratio of the bridge allowing optimized operation of the latest transmission reports, resulting in a reduction of the first report short, it is proposed to reserve for take-offs to be performed in severe, difficult and exceptional conditions, other takeoffs under usual conditions and little solicitation then taking place on the gear ratio 2nd (too long to ensure takeoffs in conditions difficult, but is well suited to takeoffs in mild conditions).

Apply the appropriate strategy while the takeoff begins or, worse, during takeoff of the vehicle, will inevitably lead to a complaint from the customer who criticizes jolts (downshift 2nd report => 1st report or fast passage 1 st => 2nd with risk of torque hole) or unpleasant behavior of his vehicle. The invention enters the decision process of selecting the gear ratio adequate transmission, including the direct selection of the 2nd report without first going through the 1st. This decision must be taken and applied before the actual take-off of the vehicle.

Thus, there is provided a method of adapting the take-off of a motor vehicle with a heat engine and an automated transmission, comprising a step of determining take-off conditions, and then adapting the gear ratio to be used for take-off, depending on the conditions, the determination step taking into account at least one parameter among the altitude, the consumption of auxiliary energy consumers of the vehicle or an engine intake temperature.

The following features may be present: [0039] the determination step takes into account the mass or a loading of the vehicle or a history of the operation of the powertrain.

[0040] the mass or the loading of the vehicle are determined at least according to an internal pressure of the tires of the vehicle, or of the ground clearance of the vehicle, or of a level of fuel in the fuel tank, or passenger detectors, or detectors for opening the front and rear passenger doors and trunk (trunk or tailgate), or the presence or absence of a trailer or caravan.

[0041] the determination step takes into account the slope.

[0042] the determination step takes into account an estimate of the characteristics of the fuel used.

[0043] the determination step takes into account the outside temperature.

[0044] the determination step takes into account the operating history of the vehicle.

The invention also proposes a motor vehicle with a heat engine and an automated transmission, comprising means for determining take-off conditions and means for adapting the gear ratio to be used for take-off as a function of the conditions, the means of determination taking into account at least one parameter among the altitude, the consumption of the auxiliary consumers of energy of the vehicle or the air intake temperature of the engine.

The invention makes it possible to adapt an existing bridge to the characteristics of the GMP and the vehicle, in order to allow the use of the entire operating range of the engine: super-economical typing, or even typing limit rolling or overloading. drive, the last report of the transmission, favorable to the approval, the comfort, the consumption and the pollutant emissions, and at the same time robustness of the takeoff, in particular vehicle in charge, engaged on a significant slope, in altitude and by external temperature elevated .

The invention describes the discrimination conditions of this takeoff to distinguish whether it will take place in difficult and exceptional conditions, or under unsolicited and customary conditions. The severity of the take-off situation is analyzed as a function of the outside temperature, the air inlet temperature of the engine, the altitude and the slope of the road, the loading of the vehicle, the estimated fuel quality from functions protection of the heat engine, the history of the operating conditions of the GMP and the vehicle over a predetermined elapsed time and the operation or not of auxiliary consumers of electrical energy, mechanical, hydraulic, pneumatic.

The invention will be better understood, and other objects, features, details and advantages thereof will appear more clearly in the explanatory description which follows with reference to the accompanying drawings given solely by way of example illustrating a embodiment of the invention and in which: - Figure 1 shows the logic of discrimination between severe conditions and usual conditions; FIGS. 2 and 3 show maps used in the logic of FIG.

In the context of an opening BV too high, party is taken to retain the available bridge positioning the gear ratio of the last report (or equivalent criterion, in the case of a CVT, and given the characteristics and dimensions of the tires adapted to the vehicle), [0050] rather than out-of-limit criteria for a vehicle speed <90km / h (in this case, the ratio of the second to last ratio is at least super-economical) and limit rollability for a vehicle speed> 110km / h, with in this case, a last report typed over-drive to lower the engine speed on a highway taxi on the flat (and therefore the fuel consumption of the vehicle during this taxi) but not robust to a request for acceleration of the vehicle and therefore having a low occurrence of passage, [0051] and preferentially positioned as a limit criterion of rollability for a vehicular speed the <90km / h and super-economical for a vehicle speed of 110km / h.

In this case, the latter report has an upper acceleration reserve, is robust to different rolling situations and is used frequently. It brings, by the associated upper acceleration reserve, a gain in absolute consumption lower but more often than in the previous case.

Consequently, given the high opening of the BV and given the dimensions of the tires selected, this choice is reflected in a gear ratio of very low 1st gear (for example less than 5km / h per 1000 revolutions / min of engine speed) and, taking into account the 1 => 2 reduction jump imposed by the internal architecture of the BV, a gear ratio of 2nd gear at or slightly higher (for example between 7 and 10km / h per 1000 revolutions / min engine speed) that would be the gear ratio of the first report of the transmission adapted to the same engine for a less demanding vehicle (mass, coast-down).

This choice is motivated by the fact that a large majority of journeys are made while the vehicle is not loaded enough (total mass close enough to its empty weight) on flat or slightly steep courses. Under these conditions, it is advisable with regard to consumption to privilege to be able to exploit more robustly the latest reports, in order to lower the average engine speed on these uses and consumption accordingly, but then with a reduction of 1 report very or even too short, given a too large opening of the transmission, in view of the occurrence of life situations the applicant.

Thus, for a type of vehicle soliciting in terms of weight and coast-down and weakly motorized (ratio between the weight of the vehicle or power under load to the wheel consumed according to a given rolling profile and the power and / or the maximum torque of the heat engine, greater than a predefined criterion), the disadvantage of a first too open transmission is used to offer two possibilities of takeoff of the vehicle, then equipped with such an automated transmission: [ 0056] - or with the first gear ratio, very short, which allows in difficult and exceptional life situations (high engine inlet temperature, high altitude and slope, large vehicle load, etc.) to quickly rev up the engine. to improve its dynamics and thus ensure a robust and efficient take-off of the vehicle (for example with regard to the vehicle speed reached at 1s or 2s or 3s from the exit of the asset), possibly at the expense of other services such as comfort, acoustics, approval or consumption; [0057] or else in life-threatening and usual situations (moderate engine inlet temperature, low altitude and incline, light-loaded vehicle, etc. but also approval cycles of consumption and emissions, cycles making it possible to measure consumption in use), with the gear ratio of 2nd gear, longer and can be judged as very long compared to gear ratios usually ensuring take-off but dimensioned to also ensure takeoff in exceptional situation of the vehicle.

However, it is accepted that a takeoff with this gear ratio of 2nd gear in exceptional conditions will be very difficult and generate discomfort (approval) and insecurity (takeoff poor performance, holes to acceleration).

Indeed, the determination of the ratio of a suitable gear to ensure the take-off of the vehicle mainly takes into account its total mass, the desired acceleration, the forces to overcome opposing the advancement of the vehicle ( rolling resistance, depending on the characteristics of the tires and the pavement of the roadway + aerodynamic drag or resistance to penetration into the air, depending on the shape of the vehicle and its speed) and the additional effort required to climb a vehicle given slope. The effort required to take off a vehicle of mass m in a slope forming an angle with the horizontal, is then obtained by writing the well-known equation of the dynamics of the vehicle:

M.7 + m.g. sin a + m.g.grow + - S.C.p. - VairY where: [0061] 7 is the acceleration of the vehicle [0062] g is the acceleration of gravity at the surface of the earth [0063] βτοηΐ 6St the coefficient of rotation: μ ^^ ηΐ = 0.01 + 10 ~ Vy is the speed of the vehicle with respect to the ground [0065] Even is the speed of the ambient air with respect to the ground [0066] P is the density of the ambient air [0067] S is the projected frontal surface of the vehicle Cx is the aerodynamic coefficient of penetration into the air.

The take-off of a vehicle is therefore strongly influenced by the total mass of the vehicle as well as by the slope in which it is engaged, the other contributions then being minor since the speed of the vehicle then changes from a zero value to a few km / h. The energy then dissipated in the clutch device (dry or wet double clutch of a DCT, torque converter of a BVA, etc. which, by its slip, infinitely increases the reduction ratio when the vehicle is stopped) is proportional to the take-off effort, to the reduction of the ratio ensuring this take-off and to the sliding rate of the clutch. The sliding of the clutch increases with the reduction of the ratio ensuring take-off. In order not to exceed the thermal capacities of the clutch system, the gear ratio of the take-off ratio must therefore be limited as a function of the slope to be climbed: the need to take off a vehicle loaded on a steep slope thus limits the reduction in the takeoff ratio and vice versa, a takeoff of a vehicle on the flat or a moderate slope allows a higher gear and allows a greater slip without harming the clutch device.

Simultaneously with its predictive detection, this takeoff is discriminated to distinguish whether it will be performed in difficult and exceptional conditions, or under unsolicited and customary conditions. The severity of the take-off situation is analyzed as a function of the outside temperature, the air inlet temperature of the engine, the altitude and the slope of the road, the loading of the vehicle, the estimated fuel quality from functions protection of the heat engine, the history of the operating conditions of the GMP and the vehicle over a predetermined elapsed time and the operation or not of auxiliary consumers of electrical energy, mechanical, hydraulic, pneumatic.

During take-off, the main important characteristic of the vehicle is its total mass, which should be estimated. The mass of the vehicle is at all times the sum of its unladen mass (which is known according to the model, the engine, the level of equipment or options, etc.) and the mass of load applied to it (driver and passengers, on-board fuel mass, mass placed in the boot and / or on the passenger seat and / or on the rear seats (bench seat (s), separate seats) and / or on a gallery or roof bars above of the vehicle, towed mass).

A vehicle according to the invention is capable of autonomously giving an estimate of its total mass by the use of indirect information, which are: [0073] the pressure and the internal temperature of the tires, the temperature outside their vicinity (for each wheel) and the atmospheric pressure, [0074] a particular treatment of the signals exchanged by the unintentional crossing warning devices (AFIL) via an evolution thereof, [0075] the fuel level in the fuel tank for estimating the on-board fuel mass, [0076] the information transmitted by the opening sensors of the front and rear passenger doors and of the trunk (trunk or tailgate), [0077] - the information transmitted by the passenger sensors and seat belt safety switches of the passenger seats and the rear seats (seat or chairs separated in rows 2, 3, beyond), [0078] trainings transmitted by the interlock switch and the presence of the folding rear seat (in whole or in 2 / 3-1 / 3) or rear seats (if folded or removed from the vehicle), [0079] - the presence or absence of a trailer or a caravan, via the wiring of the associated socket (control of the stop, fog, reversing and flashing lights) or via the electronic trailer system interfacing with the CAN (Controller Area Network, or any electrical network / multiplexing electronics) and the ABS (Antiblockiersystem or anti-lock braking system) of the vehicle.

The mass of a vehicle being transmitted to the road by means of its tires, the sum of the loads supported by each of the tires reciprocally represents the total mass of the vehicle (including its payload). Thus we can reason by considering initially a tire suspended off the ground, therefore not subject to its own weight or the reaction of the ground. In this case, the outer wall of the tire is in equilibrium between the internal pressure and the atmospheric pressure which are distributed uniformly over the entire circumference of the tire. The internal pressure plates the sidewalls of the tire on the inner edges of the rim of the wheel thus ensuring the tightness. When the wheel attached to the vehicle now rests on the ground, the weight of the vehicle adds to the previous forces. The tire is deformed under the action of the vehicle weight.

The loading of the vehicle, by the additional mass that it represents, generates an increase in the internal pressure of each tire, according to the distribution of this load on each of the tires. Thus, a continuous measurement of the tire pressure, corrected by the internal temperature of each tire, the outside temperature in their vicinity and the atmospheric pressure (which varies with the altitude, which will be explained later), and compared, to overcome any deflation or puncture occurred in the meantime, with the latest pressure measurements made at the previous cut of the vehicle contact and corrected for the internal temperature of each tire and the outside temperature in their vicinity of then, allows to estimate the mass of the vehicle and possibly its loading by difference with the tire pressure measurement similarly corrected vehicle unladen.

The automatic tire pressure monitoring (TPMS) function measures the tire pressure and the tire temperature of the vehicle by a sensor installed inside the tire or in the inflation valve and sends this information in real time to the vehicle's on-board radio computer. The invention takes into account the information coming from the sensors of each tire in order to overcome any heterogeneous distribution of the load in the vehicle. The correction of the pressure by the internal temperature of each tire and the external temperature in their vicinity (for example by virtue of the ideal gas law or the Van der Waals equation) makes it possible to discriminate a variation in tire pressure due to variation of the force applied to it by the mass of the vehicle, that caused by any external event (road temperature, outside temperature, atmospheric pressure). In the context of the implementation of the invention, a prior calibration and / or a physical model, specific to each type of tire (dimensions, structure, type: tubeless or tubetype, etc.) make it possible to associate an unknown load to a measurement of pressure or pressure variation.

[0083] The Involuntary Line Crossing Alert (or AFIL) is a device that warns the driver of a vehicle when he accidentally crosses (without operating his turn signals) a continuous or discontinuous line. This technology uses information collected continuously by ground-based infrared sensors. The warning is indicated by beeps and / or vibration in the driver's seat on the side where the crossing takes place and / or in the driver's seat belt. The variations of reflection of the infrared radiation on the white bands cause the triggering of the system via the computer of the vehicle.

The invention measures the time it takes the infrared radiation to travel the distance between its implantation and the ground. Knowing the speed of propagation of infrared radiation in the air (in particular according to its temperature, hygrometry, atmospheric pressure), it is possible to deduce the ground clearance (distance between the vehicle and the ground ). The invention then uses this information, by means of a map and / or a model, to estimate the mass of the vehicle or its loading by difference with the measurement carried out unladen vehicle. The sensors are placed on the entire perimeter of the vehicle as well as on the suspension and / or transmission axes.

The infrared sensors (or any other technology) and take into account any trim variation obtained by adjustment, wear of the suspension or loading, and, the vehicle being parked with the wheels on the same side on the sidewalk and the wheels on the other side on the road, a distance between the chassis and the ground different from both sides of the vehicle. This device is complementary to the previous one: the application of a load to the vehicle solicits its suspension which allows the approximation of the chassis of the vehicle to the ground. Similarly, the application of a load to a tire increases its internal pressure and generates its deformation, to the equilibrium position where the applied load is fully supported by the tire. The associated movement and deformation of the tire generates the approach of the chassis or the underbody environment to the ground, measured by the device described above.

For the vehicles which are equipped with it, the two devices which have just been explained complement each other by the information coming from the hydraulic or hydropneumatic suspension system, which communicates to the computer the pressure necessary to allow, taking into account the loading the vehicle and driver suspension settings, adjusting (for example, keeping it constant at all times, or lowering it to facilitate loading or raising it to climb an obstacle) the height and attitude of the vehicle above ground From this information and the suspension settings in progress, it is therefore possible for the strategy to estimate the loading of the vehicle. Similarly, the information from corrector devices of the vehicle attitude (diving or pitch-up) are also taken advantage of the invention, for the same purposes.

In order to complete the estimation of the loading of the vehicle, the fuel level in the fuel tank is also taken into account in order to estimate the onboard fuel mass.

It is known that in case of non-looping or unbuckling of the seat belts (front and rear passengers, but also driver), the computer hosting the vehicle functions (BSI or intelligent service housing) acquires this information and generates a visual alert (tell-tale on the handset) and / or sound depending on the speed of the vehicle (for example, visual if the vehicle is stationary, visual and audible on the road). In order not to generate a false alarm or an untimely alarm, the associated function detects the presence of an occupant on at least one seat (including the driver's seat, but also the passenger seat and each seat in the seat or rear seats). The detection of seat occupants (via the detection of a minimum pressure on the seat and backrest and a force at the seat belt locking switch) also intervenes in the activation and triggering of the seats. airbag systems. Passenger sensing systems consist of multiple weight sensors to establish the forces that occur when the person sits, measuring the pressure on the seat. Detection systems are classified into two categories: those incorporated in the seat and those incorporated in the seat frame. The recent devices are not only able to determine the weight of the occupant on the seat but also to determine the presence of an adult, a child or even a baby seat, and compensate their measurements by the force transmitted to the ground by the feet of the occupant. The invention therefore uses this information as well as the detection of the opening of the front and rear passenger doors and the trunk (trunk or tailgate) to determine, in the loading of the vehicle, if all or part of the seats are occupied and by what types occupants or if a heavy object is placed on one or more seats or on the seat (for example in this case without transmission of effort on the ground, or on the seat only and not against the back of the seat).

The invention also uses the information transmitted by the locking switch of the folding rear seat (in whole or 2 / 3-1 / 3), or rear seats (if folded or removed from the vehicle). Indeed, in the case of a folded rear seat, the information transmitted by the passenger sensors and seat belt contactors reflect the absence of occupant on the seat but do not identify that a load him is applied from above while it is folded down. In this case, the locking switch of the folding rear seat indicates its unlocking: the strategy carried by the invention thus detects that it is so to accommodate in the vehicle a bulky object (a mattress, long cement plates , etc.). It is the same when the rear seat or the individual chairs in the rear or the front passenger seat are separated from their slides and removed from the vehicle: the strategy carried by the invention then detects that it is so to accommodate in the vehicle a bulky object. The strategy takes this information into account, which it processes in connection with the detection of the opening of the front and rear passenger doors and the trunk (trunk or tailgate), as well as with the devices explained above for measuring the pressure and the internal temperature of the tires and the outside temperature in their vicinity (for each wheel) and measuring the ground clearance.

It is also known that a trailer or trailer hitched to the vehicle can be detected, especially through the connection to the vehicle wiring harness of that of the trailer or caravan, connection legally required to transmit if necessary to the trailer or to the caravan the control of the stop, fog, reversing and flashing lights. The detection implemented in the context of the present invention therefore occurs for example via grounding: if active, the strategy detects that a trailer or caravan is actually coupled to the vehicle; if inactive, the strategy detects that there is no hitch to the vehicle.

A history of the operating conditions of the GMP and the vehicle over a predetermined period of time (up to a few minutes before stopping before take-off, "stop" function of the stop system & start active or not): overlap information such as the thermal state in progress (at the time of take-off of the vehicle) and preceding the GMP (coolant temperature at the engine output, engine inlet air temperature, engine oil temperature and transmission, with, in the case of a hybrid vehicle, in addition to the temperatures of sensitive components: high voltage traction battery, electric motors, power electronics), engine speed, PMI (indicated average pressure), power at the wheel, vehicle speed, etc., can give a supplementary indication, but not sufficient in itself, on the state of loading of the vehicle, through the resultant of this loading on these conditions of exploitat ion.

The strategy carried by the invention is thus able to estimate the loading of the vehicle from the measurement of the internal pressure of the tires of each wheel and the ground clearance, the fuel level in the fuel tank. fuel to estimate the on-board fuel mass, and information transmitted by passenger sensors, seat belt contactors, the lock switch and the presence of the folding rear seat or rear seats, the information transmitted by the detectors for opening the front and rear passenger doors and the trunk (trunk or tailgate), as well as the detection of the presence or absence of a trailer or a caravan, assisted by the history over a predetermined period of time of the conditions the GMP and the vehicle.

It is known from the state of the prior art that a dynamic slope information is already provided by the ESC computer (Electronic Stability Control, also called ESP: Electronic Stability Program or DSC: Dynamic Stability Control or VSA: Vehicle Stability Assist or VSC: Vehicle Stability Control). For example, the document FR 2 828 450 describes a device for assisting the coasting maneuvers of a vehicle, which notably comprises means for estimating the slope in which the vehicle is engaged, useful for effecting a release control of the vehicle system. braking, so that the vehicle is maintained in the slope during the maneuver. The document EP 2 033 867 A2 presents a system comprising a calculation means for calculating the slope of the track on which the vehicle is located and means of action to act on the braking system and the management of the engine in function. the value of said slope. The calculation means takes into account, in its calculation algorithm, the value of the steering wheel angle, measured by a steering wheel angle sensor, to correct the calculation of the slope, so as to have a good detection and a good slope estimation in wheel steering situations in the direction of the slope. The strategy described in the present invention takes this information into account, which it therefore preferably receives from the ESC computer or alternatively GPS, which jointly provides the altitude of the point where the vehicle is located.

The altitude can also be provided by the GPS. In case of unavailability of this function, the strategy proposed by the invention calculates or interpolates in a mapping previously installed in the computer, from the outside temperature, the atmospheric pressure and hygrometry. The calculated version is for example from the hydrostatic equation which describes the variation of the pressure and the density of the air in the atmosphere. This equation is written:

Where: P is the atmospheric pressure, h the altitude, g the acceleration of gravity, M the average molar mass of the gases present in the atmosphere, R the universal constant of the perfect gases and T the absolute temperature. This equation thus indicates how much of the atmospheric pressure varies for a small variation dh of the altitude and vice versa, in the context of the present application, at which variation of altitude dh corresponds a variation dp of the atmospheric pressure. By the measurement of the outside temperature, it is wisely dispensed with its estimate: indeed, the outside temperature is not generally constant but varies with altitude. The most commonly accepted assumption for this variation is to assume a linear decrease in temperature with altitude.

The static and dynamic performances of the supercharged or non-supercharged engine engines degrade greatly as the engine input temperature increases and / or the atmospheric pressure decreases in connection with the rise in altitude. For a given engine (for example supercharged), the evolution of the maximum static and dynamic torque at full load (dynamic torque at 1 second after the application of the full load) can be described in three particular life situations in the same way. next: [0098] - at an altitude of Om and a motor input temperature of 25 ° C, so under favorable conditions (cooling of the charge air with an efficiency close to 1 and no heating of the circuit of intake air between the charge air cooler (RAS) outlet and the inlet to the combustion chambers); - at an altitude of Om and a motor input temperature of 75 ° C, so under severe conditions, for example by an outside temperature of more than 30 ° C and a significant heating of the intake air in RAS output by the under hood of the vehicle; - at an altitude of 4000m and a motor input temperature of 75 ° C, so under very severe conditions, where the temperature effect is added the effect of the decrease in atmospheric pressure at altitude and the density of the air, although the outside temperature decreases with altitude.

[00101] The interpretation of the above elements in a context of takeoff of the vehicle from a stationary state, in these difficult conditions (temperature and / or altitude), shows that it is virtuous in this context to increase rapidly the engine speed to increase the available torque at the crankshaft of the engine according to the time elapsed from the actual take-off time.

[00102] Likewise, the characteristics of the fuel, such as, for example, in the case of a spark ignition engine, the RON (Research Octane Number) or MON (Motor Octane Number) of the gasoline currently used, also influences the static and dynamic performance of the engine. The octane number measures the resistance of a fuel used in a spark-ignition engine to auto-ignition (ignition without intervention of the spark plug). If a fuel with an octane number that is too low (relative to the characteristics of the engine, such as its compression ratio) is used, the fuel may ignite spontaneously during compression in the cylinder. This phenomenon fatigues the moving coupling and is a source of a noise characteristic of rattling. Another type of abnormal combustion, also due to a phenomenon of auto-ignition of the gases, because of locally unfavorable thermodynamic conditions, can appear: the rumble, which differs from the rattling by its instant of appearance, before the inflammation of the mixture controlled by the candle. This sporadic and non-reproducible phenomenon appears mainly in low-speed conditions and heavy loads (especially during take-off in difficult and exceptional situations: very heavy vehicle, sloping and at altitude, high outside temperature) and during late combustion (when example of healing strategies of rattling, as explained below).

In some countries, the available fuels are of much lower quality than fuels available in European countries for example: this quality is assessed by the octane number: under the same conditions of temperature and pressure in the combustion chamber, a fuel will self-ignite all the more easily (activation energy of combustion even lower) that its RON is low, and also by chemical additives anti-knock, lead-based (toxic, pollutant, fouling and poison for the depollution organs but still used in many countries: Nigeria, Mexico, Congo, etc.), manganese, oxygenates (alcohols, ethers).

It is known to those skilled in the art that it is possible to detect (for example via an accelerometer measuring the vibrations of the engine block) the appearance of rattling (which is a function of the fuel octane number). , but not only) and to delay the ignition advance and apply fuel enrichments of the air / fuel mixture admitted to the combustion chambers, by retarding combustion to reduce the maximum temperatures and pressures reached during combustion and therefore thus protect the engine: it is then a curative strategy. Thus, in case of detection of knocking or in cases of life where its appearance is likely, ignition of the air / fuel mixture is delayed to reduce the thermodynamic conditions favorable to knocking and therefore the risks of its appearance. However, during rumble detection, the withdrawal of advances is inhibited. Indeed, a withdrawal in advance causes a later combustion and therefore conditions favorable to the rumble. It is therefore appropriate to prohibit withdrawal of advances for a few cycles after the detection of a rumble. Other systems, called adaptive systems, are able, by the behavior of the knock detection system, to detect which octane number is used, by implementing ignition mapping (before knock correction) adapted to this fuel . Other systems still offer adaptive learning by applying an ignition advance optimized and distinct to each cylinder: the computer determines which cylinder appears rattling and corrects the advance only on it. Each cylinder having operating temperatures, filling, richness, etc. slightly different, their optimal advance will be too. The nominal value of the advance of each of the cylinders is stored in the computer and changes with aging of the engine over time according to their sensitivity to knocking. It is also known to those skilled in the art the possible estimation of the characteristics of the fuel (especially RON), for example via a network of neurons indexed in regime, load, air filling, engine thermal (coolant, oil, air admitted in the cylinders), etc., which learns the differences in advance generated by the curative rattling and not seen by the preventive, and which takes into account differences not due to fuel (outside temperature, atmospheric pressure, etc.) and whose average adaptive correction on the motor field gives a sufficiently accurate estimate of the fuel RON. However, this adaptation is also operational in the case of a development of the heat engine made with a given RON fuel and the use by the customer of the engine with a higher RON fuel. This adaptation is then done in the opposite direction of the traditional withdrawal in advance, so towards the increase of the advances, to optimize the performances of the engine and the consumption.

[00105] But the torque available to the crankshaft of the engine is not always entirely devoted to take off the vehicle (taking into account the losses in the engine coupling / BV, in the BV and in the transmissions) and the strategy described in the present invention takes into account the operation or not of auxiliary consumers of electrical energy, mechanical, hydraulic, pneumatic.

Indeed, a significant portion of torque or power can be taken to the case to ensure: [00107] - the cabin thermal comfort in refrigeration mode of the passenger compartment: mechanical or electrical drive of the air conditioning compressor, drive electric or mechanical motor-fan unit for condensation of refrigerant, electric drive of the air blower in the passenger compartment, ventilated or refrigerated seats, etc. and for each of them at varying levels, mainly depending on the outside temperature, the degree of sunshine and the cabin temperature; [00108] the passenger compartment thermal comfort in the cabin heating mode: in addition to the heat losses of the internal combustion engine in its coolant, electric consumption of heating resistances or CTP on the air entering the passenger compartment and / or on the coolant inlet of the heater, electric drive of a water pump to propel the coolant through the water core of the engine and the heater, electric drive of the blower. air in the passenger compartment, electric supply of local heating elements (steering wheel, seats, door panels, seat belts, etc.), etc. and for each of them at varying levels, mainly depending on the outside temperature and the cabin temperature; [00109] the visibility between the windows of the vehicle, towards the front (defogging or defrosting while simultaneously ensuring in certain cases the outside temperature and the hygrometry the two previous needs) and towards the rear (rear-view mirrors and heated rear window) ; [00110] - the cooling of the traction chain: electric or mechanical drive of the motor-fan unit to provide ventilation to the outside air of the radiator (s) cooling (if it is not already activated at less to an equal level to satisfy another need, such as cabin refrigeration or high-voltage traction battery in the case of a PHEV), electric drive of a water pump to propel the coolant a low-temperature water circuit through a dedicated radiator and the electrical components whose heat must be managed, etc.

The direction of the vehicle, according to whether it is hydraulically assisted (drive of the associated pump) or electrically (activation of the associated electrical components); [00112] immobilization of the vehicle: electric parking brake, hydraulic, pneumatic or electric braking system involving the associated vacuum pump drive technology; [00113] - any other function of comfort or entertainment: power supply for tablet chargers or cell phones, cigarette lighters, DVD players, game consoles, etc.

[00114] Simultaneously with, on the one hand, the detection of an upcoming take-off of the vehicle, discriminated on the other hand depending on whether it is a take-off in difficult and exceptional conditions, or little soliciting and usual, it Finally, it is a matter of anticipating it and taking off effectively with the appropriate ratio, that is to say by controlling the transmission in an appropriate manner.

[00115] Figure 1 shows the logic used to determine the conditions according to which a takeoff, detected as coming, is performed in difficult and exceptional conditions, or little solicitous and usual. The severity of the take-off situation is analyzed as a function of the external temperature 280, the inlet air temperature of the engine 200, the altitude 210 and the slope of the road 250, the loading of the vehicle 240, the quality and other characteristics of the fuel 220 estimated from engine protection functions (rumble detection and pinging), the history 260 of the operating conditions of the GMP (engine water temperatures, engine inlet air, engine oils and transmission and electrical components; engine speed, indicated average pressure ...) and the history 270 of the operation of the vehicle (power at the wheel, speed of the vehicle ...) each over a predetermined elapsed time and the operation or not 230 of auxiliary consumers d electric, mechanical, hydraulic, pneumatic energies. In what follows, the numerical values and the shape of the curves (linear portions or not) are given by way of illustration and are not binding; they strongly depend on the dimensioning of the engine (displacement, supercharging, etc.) and its adaptation (inlet intake intake air, charge air cooler, permeability of the intake and exhaust circuits), as well as the typing of the vehicle in its marketing area.

On the basis of the information 200 and 210, the model 300 calculates a biasing factor 340.

On the basis of the information 200, 210 and 220, the model 310 calculates the 350 torque availability that can be produced by the Moto-Propeller Group.

On the basis of the information 240 and 250, the model 320 calculates a bias factor 360.

On the basis of the information 340, 350, 230, 360, 260, 270 and 280, the evaluation system 330 evaluates the conditions of takeoff of the vehicle, and provides a response 370 in a form for example binary: conditions little demanding and common, or severe, difficult and exceptional conditions.

The strategy proposed by the invention evaluates or is informed of the torque actually taken from the crankshaft and therefore deduces, in real time and at any time and in view of the foregoing, the torque deduction to be deducted for the take-off of the crankshaft. vehicle: [00121] - the torque available at the crankshaft of the engine according to the engine input temperature, the atmospheric pressure and the estimated fuel quality from the engine thermal protection functions, [00122] - the operation or not of auxiliary consumers of electrical, mechanical, hydraulic, pneumatic energies, losses in the motor / BV coupling, in the BV and in the transmissions.

[00124] Among the torque or power draws detailed above, some relating to safety are not negotiable: braking and immobilization of the vehicle in the slope without backing, visibility through the front windshield. On the other hand, others relating to comfort (refrigeration or heating of the passenger compartment: load shedding of the air conditioning, reduction or stop of the supply of electric energy to the heating elements, which can require a power of up to several kW ) may be temporarily suspended without affecting the service provided to the occupants of the vehicle. Indeed, given the capacitive effect of the cabin air, the supply of frigories or calories to the cabin can be temporarily suspended, the time of the actual takeoff of the vehicle (a few seconds), without its effects (blow hot or cold) are not perceptible to the occupants of the vehicle. Thus the strategy proposed by the invention requires, if necessary, a prioritization of auxiliary consumers of energy with respect to others, in inter-service and via arbitration between the different productions and energy needs to then raise the level of priority the deduction of torque to devote to take-off and thus to the benefit of the availability of power to the wheel for the effective take-off of the vehicle.

A vehicle according to the invention is thus able to autonomously give an estimate of its total mass from the pressure and the internal temperature of the tires, the outside temperature to their vicinity (for each wheel) and the pressure the ground clearance, depending on the deformation of the tires and the loading of the suspensions under the load of the vehicle, the fuel level in the fuel tank in order to estimate the on-board fuel mass, the passenger detection at the level of the seats and backrests of passenger seat and rear seat-belt seats and seatbacks (seat or chairs separated in rows 2, 3, beyond), the presence and unlocking detection of the folding rear bench seat (in whole or in 2 / 3-1 / 3) or rear seats (if folded or removed from the vehicle), the information transmitted by the sensors opening the front passenger doors and rear and trunk (trunk or tailgate), detection of the presence of a trailer or caravan, and history over a predetermined period of time of the operating conditions of the GMP and the vehicle: thermal state in progress and preceding GMP, engine speed and load, power to the wheel, vehicle speed, etc.

The state of loading of the vehicle is evaluated according to several states: PV (empty weight): weight of the vehicle in running order (full of fuel, oil, coolant, tools and spare wheel provided by the manufacturer ) without passengers or drivers; GVWR (permissible gross weight): the maximum permissible weight a vehicle (unladen weight) can reach with its load (passengers, driver and baggage); PTRA (total permissible gross weight): sum of the PTACs of the towing vehicle and that of the trailer; CD (payload): the difference between the PTAC and the unladen weight (maximum load that can be put in the vehicle).

The strategy proposed by the invention is therefore able to position the vehicle load between the PV and the PTRA. In order to discriminate the resistance to the progression of the vehicle due to the slope (product of the weight of the vehicle and the sinus of the angle formed by the rising road and a fictional horizontal), a first mapping presented in Figure 2 determines a first level of severity according to the state of loading of the vehicle and the slope in which the vehicle is engaged: a first domain A represents the place of less demanding or usual conditions, and a second domain B represents the place of difficult or exceptional conditions . The border may be a place of iso-resistance to the vehicle's progress due to the slope as a function of the variation of the mass of the vehicle (solid line), or linear (dashed line).

This map is used by the model 300 shown in FIG. 1.

Similarly, a second mapping presented in FIG. 3 determines a second level of severity as a function of the altitude and the temperature of the air admitted to the inlet of the combustion chambers of the heat engine: a first domain C represents the place of unsolicited or usual conditions, and a second area D represents the place of difficult or exceptional conditions.

The boundary may be of concave or convex parabolic shape (solid line), or linear (dashed line), depending on the sensitivity of the heat engine, of its supercharging system (if applicable: supercharging machine, circuit of air intake) and its combustion system at the altitude and temperature of the inlet air of the combustion chambers.

This mapping is used by the model 320 shown in FIG. 1.

The conditions according to which the take-off of the vehicle, which is otherwise detected as imminent, imminent, to come, are thus discriminated according to whether it will be carried out in difficult and exceptional conditions, or little soliciting and usual. The effective takeoff is thus anticipated and is carried out with the appropriate gear ratio: the 2nd gear in the 2nd case, otherwise the 1st gear, or equivalent in the case of a continuously variable transmission (CVT). Mapping managing the sensitivity of the accelerator pedal, depending on its depression, on the driver torque will be preferentially adapted. The automated transmission must be able to ensure the takeoff of the vehicle in these conditions imperceptibly for the driver and passengers of the vehicle while preserving comfort, pleasure, acoustics and vibrations and consumption, regardless of its nature, in particular: [00133] a BVMP: the automated disengagement, selection and clutch controls in particular are compatible with it, in particular the selection of the first or second gear ratio and the management of the clutch in the associated take-off conditions, in particular the point of licking of the clutch (position of the clutch from which the crankshaft torque begins to be transmitted to the primary shaft of the BV), and the point slip of the clutch; [00134] - a DCT, whose control system command must in this case allow indifferently the selection of the first odd report of the half-box associated (that of the odd reports) and the simultaneous preselection of the next report (in this case the 1st pair ratio of the other half-box), that is to say the 2nd report, and therefore in this case the take-off of the vehicle in 1st, or the selection of the 1st even ratio of the 2nd half-box ( that of even reports) and the simultaneous preselection of the next report (in this case the 2nd odd ratio of the 1st half-box), that is to say the 3rd report, so in this case the takeoff of the vehicle in 2nd and without possible lowering to 1st gear, by operating in each case the appropriate clutch then switching from one clutch to another.

[00135] a BVA with a hydrodynamic torque converter. Again, the control system must be able to select either the 1st or the 2nd report to ensure the takeoff of the vehicle, through the action of clutches and associated brakes on the dedicated parts of planetary gear trains. The characteristic of the converter (soft / hard: in the context of the present invention, the adoption of a "hard" converter reducing losses and therefore the fuel consumption is preferred to a "soft" converter, thanks to the availability a lower gear ratio than usual), the BV hydrodynamic drag reduction strategy and the converter bridging and disassembly parameters as a function of load and engine speed are optimized. (For example: slight increase in the bridging and disassembly regimes on the 1st and 2nd gear ratios), given the smallness of the gear ratios of the 1st and 2nd gears, of the take-off role of the vehicle allotted to them ( multiplication of the engine torque), but also the lower efficiency of the converter in these life situations.

[00136] - or a CVT.

This invention makes it possible to access standardization, by limiting the diversity and using the same bridge ratio with several different GMP / vehicle adaptations (for example VP Diesel and VU gasoline), a better robustness of the takeoff, in particular vehicle in charge, engaged on a steep slope, high altitude and high outside temperature, consumption gains thanks to the use made possible of the last gear ratio (or equivalent in the case of a CVT) of the transmission: up to to 1% on WLTC (Global Harmonized Test Procedure for passenger cars and light commercial vehicles), more on highway-type driving, by lowering the operating speed of the GMP, and reducing pollutant emissions accordingly.

Claims (8)

A method of adapting the take-off of a motor vehicle with a heat engine and automated transmission, comprising a step of determining take-off conditions (330), and then adapting (370) the gear ratio to be used for take-off based on characterized in that the determining step takes into account at least one parameter among the altitude (210), the consumption of auxiliary energy consumers of the vehicle (230) or an air inlet temperature of motor (200). A method of adapting the take-off of a vehicle according to claim 1, characterized in that the determining step takes into account the mass or a loading of the vehicle (240) or a history of operation of the power train (260 ). A method of adapting the take-off of a vehicle according to claim 2, characterized in that the mass or the loading of the vehicle is determined at least as a function of an internal pressure of the tires of the vehicle, or of the ground clearance. the vehicle, or a fuel level in the fuel tank, or passenger sensors, or detectors for opening the front and rear passenger doors and the trunk, or the presence or absence of a trailer or a caravan. 4. A method of adapting the take-off of a vehicle according to one of claims 1 to 3, characterized in that the determining step takes into account the slope (250). 5. A method of adapting the take-off of a vehicle according to one of claims 1 to 4, characterized in that the determining step takes into account an estimate of the characteristics of the fuel used (220). 6. A method of adapting the takeoff of a vehicle according to one of claims 1 to 5, characterized in that the determining step takes into account the outside temperature (280). 7. A method of adapting the takeoff of a vehicle according to one of claims 1 to 6, characterized in that the determining step takes into account the operating history of the vehicle (270). A motor vehicle with a heat engine and an automated transmission, comprising means for determining take-off conditions and means for adapting the gear ratio to be used for take-off according to the conditions, characterized in that the determination means take into account has at least one parameter among the altitude, the consumption of the auxiliary consumers of energy of the vehicle or the inlet air temperature of the engine.