FR2935442A1 - Torque control method for internal combustion engine of car, involves controlling torque by periodic variation of torque convergent towards torque set point, where variation is started by inversion of direction of monotonous variation - Google Patents

Abstract

The method involves detecting a set point of torque (C1) of an engine i.e. internal combustion engine. The engine torque is controlled by monotonous variation of the engine torque convergent towards the engine torque set point and periodic variation of the engine torque convergent towards the engine torque set point, where the periodic variation is started by an inversion of a direction of monotonous variation.

Description

METHOD FOR CONTROLLING THE TORQUE OF A VEHICLE ENGINE

The present invention relates to a method for controlling the torque of a vehicle engine. The user of a vehicle may in some situations suddenly require a change in engine torque, whether it is an acceleration or deceleration. The user wants the change of engine torque to take place as soon as possible after the moment when the user has requested a change in engine torque. However, when the change of the engine torque is too sudden, the vehicle undergoes jolts unpleasant for the user of the vehicle.

[0003] US-A-5,740,045 thus describes a method for varying the output torque of the engine by controlling the ignition time to control the motor speed through a motor speed target.

[0004] Document FR-A-2 766 872 describes a method for correcting the torque jolts of an internal combustion engine of the type comprising an engine control electronic system determining according to the operating conditions of the engine, the values of the motor control parameters, whereby at least one control parameter is corrected in response to oscillations of the motor torque. The method comprises the step of calculating the value of said control parameter directly as a function of the position of the accelerator pedal and determining the correction to be applied to said control parameter by filtering the rotational speed of the motor shaft.

[0005] JP200064894 discloses a torque control device for an internal combustion engine. The document FR-A-2 861 023 describes a detection installation for detecting the request of a vehicle driver wishing a global thrust torque to be provided by the vehicle during a current thrust mode. At least two of the following signals: a brake signal representing the actuation of the brake pedal by the driver, an accelerator pedal signal representing the actual position of the accelerator pedal, a speed signal representing the current speed of the vehicle and a force flow signal which represents the force flow in the transmission line of the vehicle and / or a status signal representing the status of a vehicle speed regulator and for transmitting a signal of driver request representing the desired overall thrust torque.

[0007] EP-B1-0 903 257 discloses a torque control apparatus for an internal combustion engine mounted on a vehicle, comprising an external functional acceleration and deceleration control means and a detection means of sudden acceleration operation for detecting the presence or absence of a sudden acceleration operation by said acceleration and deceleration control means. The apparatus further comprises correction means, when the presence of the sudden acceleration operation is detected by said sudden acceleration operation detecting means, for correcting the engine torque using a predetermined phase difference. and a torque variation model both of which are predetermined with respect to the engine acceleration condition to suppress vibrations occurring due to the change in the propulsive force of said internal combustion engine to a transmission, wherein, said correction means corrects the engine speed with a fluctuating engine speed variation value. Said variation value of the fluctuating motor speed is established by subtracting a speed of the reference motor from the present speed of the motor.

JP2006275060 discloses a device for controlling a motor for a vehicle.

However, the devices and methods described in the documents cited above lack effectiveness.

[0010] There is therefore a need for a motor torque control method that is more efficient. For this purpose, the invention proposes a method for controlling the torque of a vehicle engine comprising detecting an engine torque setpoint, an engine torque control comprising: a phase of monotonic variation of the convergent motor torque to the motor torque setpoint, • a period of periodic variation of the convergent motor torque towards the motor torque setpoint, the periodic variation phase starting with a reversal of the direction of the monotonic variation. [0012] In a variant, at the end of the monotonic variation phase, the motor torque control is equal to the motor torque setpoint.

In a variant, at the end of the periodic variation phase, the motor torque control is equal to the motor torque setpoint.

In a variant, the periodic variation of the torque is in a half-period.

In a variant, the monotonic variation phase corresponds to an increasing motor torque command and the periodic variation phase starts with a decreasing motor torque command.

In a variant, the monotonic variation phase corresponds to a decreasing engine torque command and the periodic variation phase starts with a rising engine torque command.

In a variant, the engine torque setpoint corresponds to the position of the acceleration pedal of the vehicle.

In a variant, the duration of the variation phases is predetermined.

In a variant, the amplitude of the periodic variation phase is predetermined. In a variant, the periodic variation phase is according to a sinusoidal, triangular or elliptical shape signal.

In a variant, the engine torque setpoint has the shape of a slot.

The present invention also relates to a vehicle whose computer implements the method described above for controlling the engine torque.

The invention advantageously makes it possible to limit the complexity of the control strategies while ensuring a good damping of the oscillations of a vehicle during a variation of the driver torque demand.

Other features and advantages of the invention will appear on reading the following detailed description of the embodiments of the invention, given by way of example only and with reference to the drawings which show: FIG. 1 , a diagram of an exemplary implementation of the method and • Figure 2, a diagram of another example of implementation of the method.

There is provided a method of controlling the torque of a vehicle engine comprising detecting an engine torque setpoint and a motor torque command. The control of the engine torque comprising a monotonic variation phase of the converging motor torque towards the engine torque setpoint and a phase of periodic variation of the convergent motor torque towards the engine torque setpoint, the periodic variation phase starting with a reversal of the direction of rotation. the monotonous variation.

The method can effectively limit jerks and rebounds of the vehicle felt by the driver during acceleration or deceleration too violent. In addition, the method allows to keep a good brio that is to say that the change in engine torque takes place as soon as possible after the moment when the user requested a change in engine torque.

The control method can be implemented in a computer in a vehicle, the vehicle comprising a motor whose torque is controlled by the computer. The implementation of the method has the advantage of occupying little memory space and using few calibration labels. The calibration labels correspond to the parameters of the computer to be adjusted during engine tuning. Calibration labels can include constants, tables in vector form or two-dimensional maps. The process thus makes it possible to reduce the risk on the quality given the large number of calibration labels to be controlled during the development of the engine. In addition, the focus time of the motor is reduced.

The control method is illustrated by Figures 1 and 2 which show diagrams of examples of implementation of the method. More precisely, FIGS. 1 and 2 illustrate the time evolution of the engine torque setpoint and the engine torque control.

The method comprises detecting an engine torque setpoint. In particular, the engine torque setpoint may correspond to the position of the acceleration pedal of the vehicle. For example, the more the vehicle acceleration pedal is depressed, the higher the engine torque set point. Similarly, the more the accelerator pedal is released and the lower the motor torque setpoint.

By way of illustration, the engine torque setpoint may have the shape of a slot as in the examples of Figures 1 and 2. The engine torque setpoint curve is the curve in phantom. Such a setpoint is generated by a sudden change in the user's request. When the user accelerates suddenly, for example by pressing the accelerator pedal, the sudden change in torque can result in a motor torque setpoint in the form of an ascending slot as in Figure 1. According to the example of FIG. 1, the setpoint of the engine torque is the torque C1 before the instant t1 then the torque C2 after the instant t1, the torque C1 being less than the pair C2. In the case of a release of the accelerator pedal, the engine torque setpoint has the shape of a falling slot as shown in FIG. 2. In the example of FIG. 2, the setpoint of the engine torque is equal to torque C4 before time t4 then torque C5 after time t4, torque C4 being greater than torque C5. The control method further comprises a motor torque control comprising a phase of monotonic variation of the converging motor torque to the motor torque setpoint. In Figures 1 and 2, the engine torque control is solid line. The monotonic variation phase takes place between instants t1 and t2 for FIG. 1 and between instants t4 and t5 for FIG. 2. It is also possible to consider that the monotonic variation phase introduces a time delay given by the difference between times t1 and t2 for Figure 1 and times t4 and t5 for Figure 2. The choice of the delay value is a compromise. The delay is not too important to ensure a good brio but the delay is not too small to avoid jolts.

According to the examples of Figures 1 and 2, the variation phase is ramps. Other forms are nevertheless conceivable as a signal resulting from a filtering of the first or second order of requested torque. Such signals have the advantage of being simple signals to implement. The memory space taken in the computer to generate them is particularly reduced.

During the monotonic variation phase, the motor torque control converges to the motor torque setpoint. This means that the command tends to the setpoint. It is possible that the command does not reach the setpoint. But the opposite can also be implemented. Thus, in the examples of FIGS. 1 and 2, at the end of the monotonic variation phase, the motor torque control is equal to the motor torque setpoint. This means that the control of the engine torque is worth the torque C2 at the instant t2 in the example of FIG. 1 and the torque C5 at the instant t5 for FIG. 2. This makes it possible to obtain a motor torque control which close to the value of the engine torque at the end of the monotonic variation phase. The control also includes a phase of periodic variation of the converging motor torque to the motor torque setpoint, the periodic variation phase beginning with an inversion of the direction of the monotonic variation. In the example of FIGS. 1 and 2, the periodic variation phase takes place between the instants t2 and t3 for FIG. 1 and between the instants t5 and t6 for FIG. 2. For FIG. 1, the control signal decreases until to the value C3 while the ramp between the values C1 and C2 is increasing. Similarly, for FIG. 1, the control signal increases up to the value C6 while the ramp between the values C4 and C5 decreases.

The phase of periodic variation allows damping of the stresses exerted by the torque on the vehicle during the monotonous variation phase.

The damping relates in particular to the driving elements of the vehicle. This makes it possible to generate a control of the engine torque that effectively damps jerks and bouncing of the vehicle felt by the driver during acceleration or deceleration too violent. In addition, the command keeps a good brio during an acceleration since the torque setpoint requested by the user is reached quickly.

In the example of FIGS. 1 and 2, the monotonic variation phase takes place between the instants t2 and t3 for FIG. 1 and between the instants t5 and t6 for FIG. 2. The phase of periodic variation in the examples such figures is an elliptical shaped signal. An elliptic signal is a signal that is a piece of a complete ellipse. Other forms of signals are nevertheless conceivable as a sinusoidal or triangular signal. Such signals have the advantage of being simple to implement.

In addition, the periodic variation of the torque is limited in time according to a half-period. This makes it possible to limit the duration of the phase of periodic variation of the couple while obtaining a good control of jolts.

During the monotonic variation phase, the engine torque control converges to the engine torque setpoint. This means that the command tends to the setpoint. It is possible that the command does not reach the setpoint. Thus, at the end of the periodic variation phase, the motor torque control is equal to the motor torque setpoint. This allows that at the end of the command, the motor torque setpoint is actually reached. Thus, at time t3, the control of the motor torque is equal to the torque C2 according to the example of FIG. 1 and at time t6, the control of the motor torque is equal to the torque C5 according to the example of FIG. The duration of the variation phases may be predetermined. This optimizes the efficiency of the control applied to the engine torque according to the setpoint. Thus, the duration of the monotonic variation phase can be chosen to have a fast convergence towards the motor torque setpoint. The duration of the periodic variation is advantageously chosen to better dampen the variations in the behavior of the car and in particular to avoid the jolts generated by the monotonous variation of the engine torque.

The duration of the phases of variations can also be connected. It is necessary to implement a phase of periodic variation of a duration adapted to the resonance frequency of the vehicle. Indeed, shortening the duration of the monotonous variation phase increases the stresses applied by the engine torque on the vehicle. It is therefore useful to correctly dampen the effect of the monotone variation of the torque by adapting the phase of periodic variation. Advantageously, to ensure good damping of the stresses generated during the monotonic variation phase, the frequency of the periodic variation phase may be equal to the resonant frequency of the vehicle.

The amplitude of the periodic variation phase can also be predetermined. The amplitude of the periodic variation is advantageously chosen to better dampen the variations in the behavior of the car and in particular to avoid the jolts generated by a sudden change in acceleration. By way of illustration, in the example of FIG. 1, the amplitude of the variation phase corresponds to the difference between the torque values C2 and C3. Similarly, in the example of FIG. 2, the amplitude of the variation phase corresponds to the difference between the torque values C6 and C5. The choice of the amplitude of the periodic variation phase may furthermore be related to the choice of the duration of the phases of variations. In particular, when the duration of the monotonic variation phase is short, the stresses applied by the engine torque on the vehicle are greater. It is therefore necessary to increase the depreciation introduced by the periodic variation phase. Increasing the amplitude of the periodic variation phase makes it possible to achieve such an effect. Advantageously, to ensure good damping of the stresses generated during the monotonic variation phase, the amplitude of the periodic variation phase may be inversely proportional to the duration of the monotonic variation phase.

FIG. 1 illustrates an example of increasing motor torque setpoint. When the engine torque setpoint is increasing, the monotonic variation phase corresponds to an increasing motor torque command and the periodic variation phase starts with a decreasing motor torque command. According to the example of FIG. 1, the monotonic variation phase increases between the values C 1 and C 2 while the phase of periodic variation starts with a decrease towards the value C 3. This ensures a good limitation of the variations of behavior of the car in the case of an acceleration.

According to the example of Figure 2, the motor torque setpoint is decreasing. In such a case, the monotonic variation phase corresponds to decreasing motor torque control and the periodic variation phase starts with increasing motor torque control. According to the example of FIG. 1, the monotonic variation phase decreases between the torque values C4 and C5 while the phase of periodic variation starts with a growth towards the torque value C6. This makes it possible to limit the variations of behavior of the car in the case of a deceleration.

Claims (12)

REVENDICATIONS1. A method for controlling the torque of a vehicle engine comprising the detection of a motor torque setpoint, and a motor torque control comprising a phase of monotonic variation of the convergent motor torque towards the motor torque setpoint a variation phase Periodically, the motor torque converges towards the motor torque setpoint, the periodic variation phase beginning with an inversion of the direction of the monotonic variation. 2. The method of claim 1, wherein at the end of the monotonous variation phase, the engine torque control is worth the engine torque setpoint. 3. The method according to one of claims 1 or 2, wherein at the end of the phase of periodic variation, the engine torque control is worth the engine torque setpoint. 4. The method according to one of claims 1 to 3, wherein the periodic variation of the torque is in half a period. The method according to one of claims 1 to 4, wherein the monotonic variation phase corresponds to an increasing motor torque control and the periodic variation phase starts with decreasing motor torque control. The method according to one of claims 1 to 4, wherein the monotonic variation phase corresponds to decreasing motor torque control and the periodic variation phase starts with increasing motor torque control. 7. The method according to one of claims 1 to 6, wherein the engine torque setpoint corresponds to the position of the acceleration pedal of the vehicle. 8. The method according to one of claims 1 to 7, wherein the duration of the phases of variation is predetermined. 9. The method according to one of claims 1 to 8, wherein the amplitude of the periodic variation phase is predetermined. 10. The method according to one of claims 1 to 9, wherein the periodic variation phase is in a sinusoidal, triangular or elliptical shape signal. 11. The method according to one of claims 1 to 10, wherein the motor torque setpoint has the form of a slot. 12. Vehicle comprising a computer implementing the method according to one of claims 1 to 11, a motor, the engine torque being controlled by the computer.