EP3655300A1

EP3655300A1 - Method for managing a traction chain of a motor vehicle

Info

Publication number: EP3655300A1
Application number: EP18752588.6A
Authority: EP
Inventors: François-Jacques CORDONNIER; Frédéric DOMPROBST
Original assignee: Compagnie Generale des Etablissements Michelin SCA
Current assignee: Compagnie Generale des Etablissements Michelin SCA
Priority date: 2017-07-19
Filing date: 2018-07-18
Publication date: 2020-05-27
Also published as: FR3069223B1; US20200164889A1; US11400946B2; FR3069223A1; WO2019016471A1

Abstract

The invention relates to a method for managing a traction chain (3) of a motor vehicle (1). According to the invention, the method comprises the following steps: a) determining a predictive rolling resistance coefficient (Crr) of at least one pneumatic tyre (10) of the motor vehicle (1); and b) adapting the operation of the traction chain (3) according to the predictive rolling resistance coefficient (Crr) in order to particularly optimise the energy consumption of the motor vehicle (1).

Description

METHOD FOR MANAGING A TRACTION CHAIN OF A VEHICLE

AUTOMOBILE

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a method for managing a power train of a motor vehicle.

TECHNICAL BACKGROUND OF THE INVENTION

In a motor vehicle, it becomes essential to optimize the energy consumption of the motor vehicle. Indeed, between the scarcity and the price of fossil fuels, the regulation of pollutant emissions and the complexity of the powertrain, it becomes difficult to be able to drive a motor vehicle optimally.

More particularly, for motor vehicles with electric drive, autonomy is a strong issue that requires optimal management of available energy. SUMMARY OF THE INVENTION

The object of the invention is to propose a method for managing a traction system of a motor vehicle that makes it possible to better predict the behavior of the tire to help optimize the energy consumption of the motor vehicle.

For this purpose, the invention relates to a method for managing a power train of a motor vehicle, characterized in that it comprises the following steps:

a) determining a rolling resistance coefficient predictive of at least one tire of the motor vehicle;

b) adapting the operation of the power train according to the predictive rolling resistance coefficient, in particular in order to optimize the energy consumption of the motor vehicle.

Advantageously according to the invention, the method makes it possible to determine the future evolution of the rolling resistance coefficient of a tire incorporated in a motor vehicle. This predictive rolling resistance coefficient is a new value that can be particularly useful for various control systems of a motor vehicle.

Advantageously according to the invention, the method makes it possible in particular to control the traction system of the motor vehicle more finely by having the future evolution of the rolling resistance coefficient of each tire, for example to determine when to change the ratios of a box. of speeds, to adapt the torque subjected to the tire for speed regulation, to adapt the movement of a controlled clutch and more generally to optimize the operation of the motor vehicle. In addition, in the case of a hybrid motor vehicle with multiple energy sources, it is particularly useful to use the future evolution of the tire rolling resistance coefficient to determine which source of energy is to be used. used and / or recharged and according to which piloting. In a related way, it also becomes possible to better know the autonomy of the energy sources used and to be able to better inform the user of the motor vehicle.

According to other optional features of embodiment of the invention:

step a) is carried out starting from at least one of the pressure, the temperature, the load and the speed of rotation of the tire, and the characteristic data of the tire;

step a) also takes into account the ambient temperature where the tire is located;

step a) is carried out from the equation:

Crr (t) = Crr _stab (T _amb , C, P, V) - [1 + k- (T (t) - T _stab ) in which CVr _sto ¾ corresponds to the minimum rolling resistance coefficient value, T is the internal temperature of the tire, T _sta b is the stabilized internal temperature of the tire at the operating point C, P, V, T _am b and k is the coefficient of sensitivity of the rolling resistance to the temperature ;

step a) also takes into account the wear of the tire;

step a) is carried out even when the motor vehicle is stationary;

step a) is carried out as long as the temperature of the tire measured during step a) is greater than a reference temperature;

- the reference temperature is greater than or equal to the ambient temperature where the tire is located;

the adaptation of step b) also takes into account a predictive variation of altitude of the motor vehicle;

the adaptation of step b) also takes into account a predictive variation of the speed of the motor vehicle;

step b) adapts the operation of a gearbox and / or a motor of the power train.

BRIEF DESCRIPTION OF THE DRAWINGS

Other particularities and advantages will emerge clearly from the description which is given hereinafter, by way of indication and in no way limiting, with reference to the appended drawings, in which:

FIG. 1 is a schematic view of a motor vehicle using a method management system of a traction chain according to the invention;

FIG. 2 is a partial sectional view of an example of a pneumatic tire monitored by the method according to the invention;

- Figure 3 is a block diagram of a method of managing a traction chain according to the invention.

DETAILED DESCRIPTION OF AT LEAST ONE MODE OF CARRYING OUT THE INVENTION

In the different figures, the identical or similar elements bear the same references, possibly supplemented by an index. The description of their structure and function is therefore not systematically repeated.

By "tire" is meant all types of elastic bandages subjected to internal pressure.

"Tread" means a quantity of rubber material delimited by lateral surfaces and by two main surfaces, one of which, called the tread surface, is intended to come into contact with a roadway when the tire is rolling.

The invention applies to any type of pneumatic tire, in particular those intended to equip motor vehicles of tourism type, SUV ("Sport Utility Vehicles"), two wheels (in particular motorcycles), planes, industrial vehicles chosen among vans, "Heavy goods vehicles" - that is, metros, buses, road transport vehicles (trucks, tractors, trailers), off-the-road vehicles such as agricultural or civil engineering vehicles - or other vehicles transportation or handling.

In all that follows, the orientation terms refer to the orthogonal reference taken with reference to the normal direction of movement of a motor vehicle 1, shown in FIG. 1 and in which there are:

a longitudinal axis X, horizontal extending from the rear towards the front;

- a transverse axis Y, horizontal extending from right to left; and

a vertical axis Z extending from bottom to top.

The term "horizontal" is defined with respect to the plane XY, the term "vertical" is defined with respect to the plane XZ or YZ.

The invention relates to a method of managing a traction chain of a motor vehicle comprising a step of determining the rolling resistance coefficient of one (or more) tire (s) pneumatic (s). Indeed, it has been found that from the measurement of the state of a tire, it was possible to determine future revolution of the rolling resistance coefficient of the tire. However, advantageously according to the invention, this type of information is not currently available while it allows to better manage for example the energy of a motor vehicle.

It is understood that the traction chain of the motor vehicle can be driven more finely by having this information for example to determine when to change gear ratios, to adapt the torque subjected to the tire for speed control , to adapt the movement of a controlled clutch and more generally optimize the operation of the motor vehicle.

In addition, in the case of a hybrid motor vehicle with several energy sources such as electric, pneumatic or thermal, it is particularly useful to use the future evolution of the rolling resistance coefficient of the tire to determine which energy source should be used and / or recharged and according to which direction. In a related way, it also becomes possible to better know the autonomy of the energy sources used and to be able to better inform the user of the motor vehicle.

By way of no limitation, for hybrid motor vehicles, it is sometimes used a strategy of ECMS type (abbreviation from the English term "Equivalent Consumption Minimization Strategy"). It is a real-time control strategy based on the theory of optimal control. It consists in considering the electric accumulator of the motor vehicle as an auxiliary fuel tank, and in choosing the control which minimizes the total energy taken from the two tanks. A coefficient acting as a variator of the price of electrical energy is used. The bigger it is, the more expensive the electric energy is to use, and the more interesting it will be to recover (by regeneration). The weaker it is, the more inexpensive the electric energy, so it is interesting to use in conjunction with the heat engine, or alone. It is therefore immediate that this coefficient is influenced by the amount of energy recoverable especially during braking which depends on the rolling resistance of the tires at the time of driving.

Advantageously according to the invention, it has been found that the coefficient of rolling resistance of tires, and therefore the consumption of a motor vehicle, varies in particular as a function of the speed of rotation of the tire, the temperature of the tire. , the load of the tire and the pressure of the tire.

The study has indeed revealed that the rolling resistance coefficient of a tire decreases between its cold state and its hot state to a minimum value specific to the tire according to the above characteristics. Thus, the higher the speed and / or the longer the driving time, the more the rolling resistance coefficient will quickly approach its minimum value. As illustrated by way of example in FIG. 2, a tire 10 comprises a structure 12 and a tread 14. The structure 12 comprises a central armature 16 extended by two external flanks F and two beads B sometimes called low zones. A single flank F and a single bead B are shown in FIG. 2. The tread 14 and the central armature 16 of the structure 12 form an apex S of the tire 10.

Two rods 18 (only one is shown) are embedded in the beads B. The two rods 18 are arranged symmetrically with respect to a median radial plane M of the tire 10. Each rod 18 is of revolution about a reference axis. This reference axis, substantially parallel to the direction Y, is substantially coincident with an axis of revolution of the tire 10.

The tread 14 comprises sculptures 20. The armature 16 comprises metal plies 26, 28 and 30 embedded in masses of rubber 32 and 34. A mass of rubber 36 extends radially from the vertex S to the level of the rod 18 of the bead B defining an outer surface 37 of the sidewall F and the bead B. In addition, in the example described, the bead B comprises an annular sheet 38 consisting of metal reinforcements inclined relative to the circumferential direction

The tire 10 also comprises a waterproof inner rubber ply 40 and a carcass ply 42. These plies 40 and 42 are generally toroidal in shape and are both coaxial with the rods 18. The plies 40 and 42 extend between the plies. two annular rods 18 of the tire 10 passing through the apex S. The carcass ply 42 wraps around the rods 18 by virtue of its ends 44 each forming a reversal on one of the rods 18. The ply 40 has an inner surface 43 intended to to be in contact with the air contained within the tire 10.

The bead B also comprises a mass of protective rubber 46 annular intended to allow, in part, the radial and axial attachment of the tire 10 on a rim. The bead B of the tire 10 also comprises masses of tamping rubber 48, 50 of a volume V between the carcass ply 42 and the mass 36.

It is therefore clear that each tire 10 has its own characteristic data according to its architecture and its materials used. The rolling resistance coefficient of a tire 10 will therefore be deduced by prior measurements of the tire 10 on test benches and / or simulations by varying the rolling conditions to obtain, for example, models in thermomechanical finite elements.

The invention relates to a method for managing a traction chain 3 of a motor vehicle 1 comprising a first step a) intended to determine the predictive rolling resistance coefficient Crr of at least one tire 10 of the motor vehicle 1 and a step b) intended to adapt the operation of the traction chain 3 according to the predictive rolling resistance coefficient Crr in order to optimize the energy consumption of the motor vehicle 1.

Step a) is carried out starting from at least one of the pressure P, the temperature T, the load C and the rotational speed y of the tire 10. This step a) can for example be carried out at using a monitoring system 51 provided with a device 53 for measuring the state of the tire 10 arranged to determine at least one of the pressure, the temperature, the load and the speed of rotation of the tire 10. Such a measuring device 53 may for example comprise at least one detection element 52 mounted in the tire 10. By way of example illustrated in FIG. 1, the motor vehicle 1 may thus comprise a measuring device 53 comprising an element 52i, 52 ₂ , 52 ₃ , 52 ₄ of detection in each tire 10i, 10 ₂ , 10 ₃ , 10 ₄ . Such detection elements 52 could for example be of the TMS type (abbreviation from the English term "Tire Mounted System") and each be attached against the inner surface 43 of a tire 10 as disclosed by way of example in the document EP 0 887 211. Of course, the measuring device 53 can also collect measurements already accessible by the motor vehicle 1 such as, for example, the ambient temperature T _am b, the load C and the speed y of the motor vehicle 1.

Step a) can then calculate the predictive rolling resistance coefficient Cr based on these data. It will therefore be understood that step b) can for example determine the predictive rolling resistance coefficient Cr from the thermomechanical finite element models of the tire 10 explained above, possibly by means of successive iterations in order to offer the finest value possible. This determination of the resistance coefficient Crr can also be performed by comparison with a known law of behavior, on the basis of physical measurements. Of course, the thermomechanical finite element models can take into account other values such as, for example, the ambient ambient temperature T _am b or the wear rate of the tire 10.

This calculation can be obtained by means of a monitoring module 55 arranged to receive the data measured by the device 53 for measuring the state of the tire 10. The monitoring module 55 can comprise a data acquisition element. data 53 of the device 53 for measuring the state of each tire 10. More particularly, the monitoring module 55 may comprise an acquisition element capable of receiving the data of each element 52 of detection of wired or wireless communication.

The monitoring system 51 may further comprise a prediction module 57 arranged to estimate the predictive rolling resistance coefficient Crr of the tire 10. The step a) could therefore be carried out by the prediction module 57 with the aid of a member 56 for storing the characteristics of the tire 10, an element 61 for calculating the data of the monitoring module 55 relative to those of the element 56 for storing the characteristics of the tire 10 making it possible to determine the evolution future rolling resistance coefficient of the tire. Each calculation can then be recorded on a storage element 58 to know the history of the calculations and to supply, for example, massive data external to the motor vehicle 1. Indeed, it is understood that after a while, the monitoring system 51 comprises a compilation of values of the rolling resistance coefficient predictive Crr recorded in the storage element 58 which makes it possible to follow the evolution of the estimated values of the rolling resistance coefficient of each tire 10 over time.

Of course, the elements used such as the element 56 for storing the characteristics of the tire 10 or the element 58 for storage are not necessarily mounted on the vehicle but could be physically deported, that is to say communicate with the motor vehicle from another place. For example, the element 56 for storing the characteristics of the tire 10 and / or the element 58 for storing the calculation history could thus belong to a server that can be remotely interrogated by a telematic system of the motor vehicle 1 .

By way of no limitation, step a) could be performed by the element 61 of calculation from the equation:

Crr (t) = Crr _stab (T _amb , C, P, V) - [1 + k- (T (t) - T _stab ) In which:

Crr _s tab is the minimum rolling resistance coefficient value of the tire 10;

T is the internal temperature of the tire;

Tstab corresponds to the stabilized internal temperature of the tire at the operating point C, P, V, T _amb ;

k is the coefficient of sensitivity of the rolling resistance to the temperature.

Of course, step a) may take into account other values such as, for example, the altitude variation and / or the variation of the regulatory speed limit and / or the wear history of the tire. accessible by the motor vehicle 1 in situ or by interrogation of a remote server. Therefore, the element The calculation method could take into account other values such as, for example, the altitude variation and / or the variation of the regulatory speed limit provided by the geolocation device 63 and / or a storage element 60 of the history of wear of each tire 10 of a measuring device (not shown) of the wear of each tire 10 already accessible by the motor vehicle 1.

According to an advantage of the management method according to the invention illustrated in FIG. 3, it is understood that the predictive rolling resistance coefficient Crr can be estimated even when the tire 10 is stationary, that is to say when the vehicle automobile 1 is stationary. The predictive rolling resistance coefficient Crr will therefore increase during the downtime or parking period. Advantageously according to the invention, it is possible to determine finely the future evolution of the rolling resistance coefficient of a tire 10. In fact, the advantage of the invention which takes into account the coefficient of predictive rolling resistance Crr especially after a immobilization of the tire 10 following a rolling of several hours. Thus, instead of considering the tire 10 as cold after immobilization, that is to say when the motor vehicle 1 stopped, the method advantageously allows to take into account the coefficient of rolling resistance predictive Crr which is much closer to reality.

Preferably, step a) is performed as long as the temperature of the tire (10) measured in step a) is greater than a predetermined reference temperature. Preferably, the reference temperature is greater than or equal to the external ambient temperature r _am ¾ as, for example, equal to r _am ¾ + 10 ° C.

Advantageously according to the invention, the method makes it possible to drive the traction chain 3 of the motor vehicle 1 via the traction chain control device 3 more finely by having the future evolution of the rolling resistance coefficient of each bandage. pneumatic 10 for example to determine when to change the ratios of a gearbox 2, to adapt the torque subjected to the tire 10 for the speed control of the motor vehicle 1, to adapt the movement of a controlled clutch and more generally optimize the operation of the motor vehicle 1.

Moreover, in the case of a hybrid motor vehicle with several energy sources such as thermal, pneumatic and / or electric, it is particularly useful to use the predictive rolling resistance coefficient Crr of each tire 10 so to determine which source of energy should be used and / or recharged and according to which control by the control device 5 of the traction chain 3. In a related way, it also becomes possible to better know the autonomy of the energy sources used and to better inform the user of the motor vehicle 1.

The invention is not limited to the examples presented and other variants will become apparent to those skilled in the art.

In particular, it is possible to carry out the processes using an indirect flow of information via a server where statistical processing is carried out on the history of the information and a massive data analysis which would make it possible to deal with the problem of evolution of the data. rolling resistance with wear using remote information sources. For example, a massive data processing with history management could be done to integrate the effects of tire wear on the value of the minimum rolling resistance coefficient, also called stabilized, coupled to the use of a device outside the motor vehicle 1 for measuring wear such as when the motor vehicle 1 is in maintenance or passes through an automatic detection gantry incrementing the number of kilometers made by the tires.

Claims

1. A method of managing a power train (3) of a motor vehicle (1), characterized in that it comprises the following steps:

a) determining a predictive rolling resistance coefficient (Crr) of at least one tire (10) of the motor vehicle (1);

b) adapting the operation of the power train (3) according to the coefficient of rolling resistance (Crr) in particular to optimize the energy consumption of the motor vehicle (1).

2. Method according to the preceding claim, wherein step a) is carried out from at least one of the pressure (P), the temperature (7), the load (C) and the speed (V) of rotation of the tire (10), and characteristic data of the tire (10).

3. Method according to the preceding claim, wherein step a) also takes into account the ambient temperature (r _am ¾) where the tire (10) is located.

4. Method according to the preceding claim, wherein step a) is carried out from the equation:

Crr (t) = Crr _stab (T _amb , C, P, V) - [1 + k- (T (t) - T _stab ) in which:

Crr _s tab is the minimum rolling resistance coefficient value; T is the internal temperature of the tire;

Tstab is the stabilized inner temperature of the tire at the point of operation

The method according to any one of claims 2 to 4, wherein step a) also takes into account the wear of the tire (10).

6. Method according to one of claims 2 to 5, wherein step a) is performed when the motor vehicle is stationary.

7. Method according to one of claims 2 to 6, wherein step a) is performed as the temperature of the tire (10) measured in step a) is greater than a reference temperature.

8. Method according to the preceding claim, wherein the reference temperature is greater than or equal to the ambient temperature (r _am ¾) where the tire (10) is located.

9. Method according to one of the preceding claims, wherein the adaptation of step b) also takes into account a predictive variation of vehicle altitude. automobile (1).

10. Method according to one of the preceding claims, wherein the adaptation of step b) also takes into account a predictive variation of the speed of the motor vehicle (1).

11. A method according to any one of the preceding claims, wherein step b) adapts the operation of a gearbox (2) of the traction chain (3).

12. Method according to any one of the preceding claims, wherein step b) adapts the operation of a motor (4) of the traction chain (3).