EP2799699B1 - Control method for a powertrain during a transition period of engine play - Google Patents

Description

The present invention relates to a method for controlling a powertrain of a vehicle during a motor grooming phase.

The invention belongs to the field of vehicles comprising a powertrain comprising a heat engine and a transmission disposed between this engine and the wheels of the vehicle.

Such vehicles are equipped with a computer to automatically adapt the operating point of each of the powertrain members, in particular the torque that is provided by the heat engine, in order to comply with a directive from the driver.

The operation of a power train with a combustion engine may be disturbed by engine play. This is a phenomenon of torsion of the transmission between the engine and the wheels that occurs between the moment the engine lands on its holds and the moment when the engine has tilted and drives the wheels of the vehicle. The phase of crossing of the engine games is defined as the range of torque for which neither the engine nor the wheel trains each other.

In a usual manner, a preventive approval function of the powertrain control system applies a filtering treatment of the torque setpoint resulting from the driver's request. This preventive approval function comprises a state called in the rest of the "traversed state of the engine games", to apply a particular torque setpoint during the crossing phase of the engine games. Thus, it allows to cross these games by avoiding strong jerks of the powertrain.

For example, the state of the art is known from the French patent application FR-2-899-282-A1 or the German patent application DE 10119724 A1 which describe a preventative approval function of a control method of a powertrain to avoid such jolts during the crossing games.

The figure 1 illustrated by graphs, the evolution as a function of time expressed in seconds (s), of torque values expressed in Newton-meter (Nm) on the top graph and a Pacc instruction set expressed in percent (%) on the bottom graph.

In a control method of a known prior art powertrain, as represented by the figure 1 , the state crossed the games The engine of a preventive approval function is determined by comparing a preventive pair Cp with a first threshold S1 and a second threshold S2.

The preventive torque Cp is calculated from a setpoint torque Cc dependent on a driver setpoint Pacc such as the position of an accelerator pedal or an acceleration lever of this vehicle.

When the preventive pair Cp is between the first threshold S1 and the second threshold S2, the preventive approval function is in the traversed state of the engine games.

The first and second thresholds S1 and S2 are in particular defined as a function of the driver set point Pacc. For example, the second threshold S2 can be defined with a value of 10 Nm for a driver instruction corresponding to a depression of 10% of the accelerator pedal, and with a value of 40 Nm for a depression of 50% of this pedal. The intermediate values of the second threshold S2 are determined by continuously interpolating a map of a computer according to the position of the accelerator pedal.

In the example of the figure 1 at time t0, the driving setpoint Pacc increases to a first stabilized value and the setpoint torque Cc, the preventive pair Cp, and the first and second thresholds S1 and S2 change accordingly.

When between the instants t1 and t2, the preventive pair Cp is between the first threshold S1 and the second threshold S2, the preventive approval function is in the traversed state of the engine games.

After the moment t2, the engine games were crossed and the tilting of the engine took place. Since the driver set point Pacc is constant and positive after this instant t2, the heat engine remains in a driving position.

At time t3, the driver setpoint Pacc increases again to a second stabilized value and the setpoint torque Cc, the preventive torque Cp, as well as the first and second thresholds S1 and S2 also increase.

Due to the increase of the first and second thresholds S1 and S2, between times t4 and t5, the preventive pair Cp is again between the first threshold S1 and the second threshold S2. The preventive approval function is therefore again in the crossed state of the engine games.

The preventive approval function thus again filters the setpoint torque Cc between instants t4 and t5 while the engine sets have already been physically crossed between times t1 and t2.

This method therefore has the disadvantage of causing a new condition traversed motor games, unnecessary, the preventive approval function that causes in many vehicle life situations a limitation (or loss) acceleration of the vehicle, also called hole to acceleration.

The object of the invention is to overcome the drawbacks of the prior art by modifying, after the phase of traversing the motor games, the calculation method of the first and second thresholds.

• à la somme d'un seuil physique et d'un seuil dynamique tant que l'état traversée des jeux moteur n'a pas été franchi ;
• uniquement à ce seuil physique après que cet état a été franchi, ceci tant que le couple de consigne est supérieur à un seuil de couple de consigne prédéfini.

For this purpose, the present invention provides a method of controlling a powertrain of a vehicle comprising at least one step of calculating a preventive torque of a heat engine to limit jolts of the powertrain, this couple preventive device dependent on a setpoint torque, the calculation step thus defined comprising a traversed state of the engine games when the preventive torque is between a first threshold and a second threshold, the method being remarkable in that one of these thresholds is legal :

• the sum of a physical threshold and a dynamic threshold as long as the crossed state of the engine games has not been crossed;
• only at this physical threshold after this state has been crossed, as long as the target torque is greater than a predefined setpoint torque threshold.

Thus, the invention makes it possible to reduce the value of the first or the second threshold, which makes it possible to avoid activating, when this is not necessary, a new traversed state of the engine games of the preventive approval function.

According to one particular characteristic, the evolution gradient of the preventive torque is lower in the traversed state of the games of the calculation step mentioned above than outside this state.

According to a particular characteristic, the setpoint torque depends on a conductive setpoint and the dynamic threshold is defined by a mapping whose input is this conductive setpoint.

According to a particular characteristic, the dynamic threshold is defined by a map whose entry is an activation state of a sport mode of the vehicle.

According to a particular characteristic, the physical threshold and / or the dynamic threshold are defined by a map whose input is the speed of the heat engine.

According to a particular characteristic, the physical threshold and / or the dynamic threshold are defined by a map whose input is the gear ratio of a transmission of the powertrain of this vehicle.

According to a particular characteristic, the driver setpoint is a position of a pedal or a vehicle acceleration lever.

According to a particular characteristic, the engine runs on gasoline or diesel.

Still for the same purpose, the present invention also proposes a remarkable vehicle in that it comprises means adapted to implement steps of a control method of a powertrain as succinctly described above.

• la figure 1, déjà décrite, représente des graphiques illustrant l'évolution d'une consigne de couple dans une étape de calcul du couple de consigne d'un moteur dans un procédé de commande d'un groupe motopropulseur d'un véhicule selon l'art antérieur ;
• la figure 2 représente un ordinogramme illustrant des étapes de calcul du couple de consigne d'un moteur dans un procédé de commande d'un groupe motopropulseur d'un véhicule selon l'invention ;
• la figure 3 représente des graphiques illustrant l'évolution d'une consigne de couple dans une étape de calcul du couple de consigne d'un moteur dans un procédé de commande d'un groupe motopropulseur d'un véhicule selon l'invention ;
• la figure 4 représente une machine à états d'un procédé de commande d'un groupe motopropulseur d'un véhicule selon l'invention ; et
• la figure 5 représente une machine à états d'une fonction de calcul d'un premier ou d'un second seuil S1 ou S2 dans un procédé de commande d'un groupe motopropulseur d'un véhicule selon l'invention.

The invention will be better understood and other aspects and advantages will appear more clearly on reading the following description of a particular embodiment, given by way of non-limiting example and with reference to the accompanying drawings. wherein :

• the figure 1 , already described, represents graphs illustrating the evolution of a torque setpoint in a step of calculating the target torque of an engine in a control method of a powertrain of a vehicle according to the prior art;
• the figure 2 represents a flowchart illustrating steps for calculating the target torque of an engine in a control method of a powertrain of a vehicle according to the invention;
• the figure 3 represents graphs illustrating the evolution of a torque setpoint in a step of calculating the target torque of an engine in a control method of a powertrain of a vehicle according to the invention;
• the figure 4 represents a state machine of a method for controlling a power unit of a vehicle according to the invention; and
• the figure 5 represents a state machine of a calculation function of a first or a second threshold S1 or S2 in a method of control of a powertrain of a vehicle according to the invention.

The invention applies to a powertrain of a vehicle comprising a heat engine running on gasoline or diesel fuel (also commonly called diesel) and a transmission disposed between the engine and the vehicle wheels.

The transmission may notably be a gearbox of the type manual gearbox (BVM), automated gearbox (BVA), manual gearbox (BVMP) or gearbox Double Clutch (English "Double Clutch Transmission" or DCT).

A computer of this vehicle makes it possible to automatically adapt the operating point of each of the powertrain members, in particular the torque supplied by the heat engine, in order to respect the driver's instruction.

The figure 2 illustrates the steps of a control method 100 for calculating the target torque of the engine of this powertrain according to the invention.

• une consigne conducteur Pacc, telle que par exemple la position d'une pédale ou d'un levier d'accélération du véhicule,
• un régime Nmot du moteur thermique,
• un rapport Rbv de démultiplication de la transmission.

A first step 10 of the control method 100 consists of interpreting the will of the driver to calculate a setpoint torque Cc as a function of several input data. This input data includes as an example:

• a Pacc instruction driver, such as for example the position of a pedal or a vehicle acceleration lever,
• a Nmot regime of the heat engine,
• an Rbv ratio of transmission reduction.

A second step 20 is a preventive approval function for calculating a specified torque reference Ci.

In this second step 20, the setpoint torque Cc is first filtered to provide a preventive torque Cp to cross the motor games by limiting jolts and to respect a predefined typing more or less dynamic vehicle.

The preventive torque Cp is then converted into a given torque setpoint Ci taking into account a couple of losses of the engine. The loss torque Cpm of the engine generally takes into account the internal mechanical friction of the engine as well as those of accessories, such as an alternator, linked to the engine.

The indicated torque Ci is equal to the sum of the preventive torque Cp and the loss torque Cpm of the heat engine: $$\mathrm{This}=\mathrm{Pc}+\mathrm{CMP}$$

In a third step 30, an optional healing approval function monitors the evolution of the engine speed. This curative amenity function can for example calculate, when the engine speed is oscillating, a correction torque Ccor, in opposition to this oscillation phase. The final torque setpoint Cf of the motor is then equal to the sum of the indicated torque Ci and the corrective torque Ccor: $$\mathrm{Cf}=\mathrm{This}+\mathrm{Ccor}$$

In order to limit jolts during a traversing phase of the engine gears, a particular filtering of the setpoint torque Cc is applied for the calculation of the preventive torque Cp.

The figure 3 illustrated by graphs, the evolution as a function of time expressed in seconds (s), of torque values expressed in Newton-meter (Nm) on the top graph and a Pacc instruction set expressed in percent (%) on the bottom graph.

When the preventive pair Cp is between a first threshold S1 and a second threshold S2, the evolution gradient of the preventive pair Cp is smaller compared to that observed when this pair is outside the range defined by the thresholds S1 and S2. .

To do this, a state machine of the control method 100, for example in step 10 or step 20, provides information on the status of the preventive authorization function of the second step 20.

During the initialization of this state machine, a nonlimiting example of which is illustrated by the figure 4 , the preventive approval function is in the pending state of an acceleration 210.

When the set torque gradient Cc is greater than a predefined threshold ε, the preventive approval function goes to the state before engine games 220.

The transition from the state before engine games 220 to the traversed state of the engine sets 230 occurs when the preventive torque Cp is between the first and second thresholds S1 and S2.

When the preventive approval function is in the traversed state of the engine sets 230, if the preventive torque Cp is greater than the second threshold S2, the function then goes into the state after the engine games 240.

From this state after engine gears 240, the transition to the waiting state of an acceleration 210 is performed when the preventive torque Cp is equal to the setpoint torque Cc.

The figure 5 represents a state machine of a calculation function of the first or second threshold S1 or S2. When the traversed state of the games 230 has not yet been crossed, that is to say, until we have gone through the state after the engine 240, the first or second threshold S1 or S2 is calculated in a state 310 and is equal to the sum of a physical threshold Sp and a dynamic threshold Sd.

When the traversed state of the games 230 has already been crossed, this first or second threshold S1 or S2 is calculated in a state 320 and is equal only to the physical threshold Sp, as long as the setpoint torque Cc is greater than a threshold of Set point torque_Cc predefined, generally between -10Nm and ONm.

When the setpoint torque Cc has fallen below the value of the setpoint threshold threshold_Cc, the first or second threshold S1 or S2 is again calculated in step 310 and is equal to the sum of the physical threshold Sp and the threshold dynamic Sd, as long as the state traversed games 230 is not crossed again.

The physical threshold Sp can for example be defined as a function of the Nmot regime of the heat engine and / or the gear ratio Rbv of the transmission.

The dynamic threshold Sd depends on the driver setpoint Pacc.

For example, the dynamic threshold Sd can also be defined as a function of the engine speed Nmot and / or of the transmission ratio Rbv of the transmission and / or the activation status of a sport mode of the vehicle.

Such an activation state of a sport mode on a vehicle is known and may for example correspond to a state of depression of a push button on the vehicle, to the particular position of a wheel or to any other interface allowing the driver to indicate his willingness to have a more dynamic vehicle (for example by means of shorter filtering times or faster changes in gear ratios).

To simplify the calculation and facilitate the development of the control method 100, a map can for example be used to determine the physical threshold Sp and the dynamic threshold Sd.

The first threshold S1 can then be equal, either only to the physical threshold Sp, or to the sum of the physical threshold Sp and the dynamic threshold Sd, the second threshold S2 being defined with respect to the first threshold S1 by means of an offset (in predefined English "offset"). Conversely, it is also possible to take as a value of the second threshold S2, either only the value of the physical threshold Sp, or the sum of the physical threshold Sp and the dynamic threshold Sd, and to define the first threshold S1 by offset from each other. at the second threshold S2.

This offset value is variable according to the heat engines. By way of nonlimiting example, it is possible to choose an offset value of between 1 and 10 Newton-meter (Nm).

So, on the graphs of the figure 3 , the preventive approval function is in the pending state of an acceleration 210 until time t0.

At time t0, the driver setpoint Pacc and therefore the setpoint torque Cc increase and the preventive approval function goes into the state before engine games 220.

The traversed state of the games 230 has not yet been crossed, the first or the second threshold S1 or S2 is then defined as the sum of the physical threshold Sp and the dynamic threshold Sd. As the dynamic threshold Sd is dependent on the driver set point Pacc, the first and second thresholds S1 and S2 increase.

At time t1, the preventive pair Cp becomes greater than the first threshold S1. The preventive approval function is then in the traversed state of the engine sets 230 until time t2 for which the preventive torque Cp becomes greater than the second threshold S2.

Between instants t1 and t2, the evolution gradient of the preventive torque Cp is then reduced by means of a larger filter applied to the setpoint torque Cc to avoid jolts.

After the instant t2, it is in the state after the engine 240 and when the preventive torque Cp becomes equal to the setpoint torque Cc, it returns to the waiting state of an acceleration 210.

After this instant t2, the traversed state of the sets 230 has already been crossed, the first or second threshold S1 or S2 is therefore equal only to the physical threshold Sp, considering that the setpoint torque Cc is greater than the setpoint torque threshold. threshold_Cc predefined.

The value of the physical threshold Sp is generally defined in a range of values between -5 Nm and 5 Nm. The value of the thresholds S1 and S2 is therefore greatly reduced from the instant t2.

At time t3, the driver setpoint Pacc and therefore the setpoint torque Cc increase and the preventive approval function goes into the state before engine games 220.

The thresholds S1 and S2 being then defined only with respect to the physical threshold Sp, the preventive pair Cp is therefore greater than the thresholds S1 and S2. The preventive approval function therefore remains in the state before the engine games 220 and no additional filtering for the passage of the engine games is applied for the calculation of the preventive torque Cp.

When subsequently (situation not shown on the figure 3 ) the driver Pacc setpoint will be reduced and will become lower than the threshold threshold driver_pacc threshold, the calculation of the first or the second threshold S1 or S2 will again be equal to the sum of the physical threshold Sp and the dynamic threshold Sd.

Thus, the implementation of the method according to the invention makes it possible to avoid activating, when this is not necessary, a new traversed state of the engine games 230 of the preventive approval function, which reduces the holes to acceleration.

Claims (9)

1. A control method (100) for a powertrain of a vehicle comprising at least one step (20) for calculation of a preventive torque (Cp) of a heat engine to limit the jerks of the powertrain, said torque (Cp) depending on a torque setpoint (Cc), said step (20) comprising a transition state of engine play (230) when said torque (Cp) is comprised between a first threshold (S1) and a second threshold (S2), said method (100) being characterized in that one of said thresholds (S1, S2) is equal:

   - to the sum of a physical threshold (Sp) and of a dynamic threshold (Sd) as long as said state (230) has not been crossed;

   - solely to said physical threshold after said state (230) has been crossed, this being as long as said torque setpoint (Cc) is greater than a predefined torque threshold setpoint (seuil_Cc).
2. The control method according to Claim 1, characterized in that the development gradient of said preventive torque (Cp) is less in said transition state of play (230) of said step (20) than outside this state.
3. The control method (100) according to Claim 1 or 2, characterized in that said torque setpoint (Cc) depends on a driver setpoint (Pacc) and in that said dynamic threshold (Sd) is defined by a mapping, an input of which is said driver setpoint (Pacc).
4. The control method (100) according to any one of the preceding claims, characterized in that said dynamic threshold (Sd) is defined by a mapping, an input of which is a state of activation of a sports mode of the vehicle.
5. The control method (100) according to any one of the preceding claims, characterized in that said physical threshold (Sp) and/or said dynamic threshold (Sd) are defined by a mapping, an input of which is the speed (Nmot) of said engine.
6. The control method (100) according to any one of the preceding claims, characterized in that said physical threshold (Sp) and/or said dynamic threshold (Sd) are defined by a mapping, an input of which is the gear ratio (Rbv) of a transmission of said powertrain.
7. The control method (100) according to any one of Claims 3 to 6, characterized in that said driver setpoint (Pacc) is a position of an acceleration pedal or lever of the vehicle.
8. The control method (100) according to any one of the preceding claims, characterized in that the heat engine operates on petrol or diesel.
9. A vehicle, characterized in that it comprises means suited to implement the steps of a control method (100) according to any one of the preceding claims.

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