WO2007116168A1

WO2007116168A1 - System for controlling the operation of a motor vehicle power plant in order to lessen the effect of play in a vehicle drive line

Info

Publication number: WO2007116168A1
Application number: PCT/FR2007/051033
Authority: WO
Inventors: Yvan Le Neindre; Stéphane Guerin; Gaëtan ROCQ
Original assignee: Peugeot Citroën Automobiles SA
Priority date: 2006-04-04
Filing date: 2007-03-28
Publication date: 2007-10-18
Also published as: FR2899282A1; FR2899282B1; EP2002102A1

Abstract

The invention relates to a system (30) for controlling the operation of a power plant GMP (12), controlled by torque and belonging to a motor vehicle, and connected to wheels of the vehicle (14, 16) in order to drive them through a drive line (18) that has mechanical play, the system comprising means (32, 34, 36, 40, 42) for acquiring a resistive torque exerted on said wheels and a reference torque for the GMP, means (38) for determining, as a function of the resistive torque and of the reference torque, a make-good reference torque for the GMP, and means (38) for delivering this to the GMP. The determining means (38) comprise first means (44) for calculating a value of the resistive torque fed back to the GMP as a function of the resistive torque acquired, and for zero torque transmitted through the drive line, and second means (46) for calculating the said make-good reference torque as a function of the calculated value of the resistive torque fed back to the GMP.

Description

System for the control of the operation of a motor-vehicle powertrain for the attenuation of disturbances during the passage of play of a transmission of the vehicle.

The present invention relates to a control system of a motor-drive unit, controlled in torque, of a motor vehicle, the power unit being connected to wheels of the vehicle for their drive through a transmission having mechanical clearances.

The invention is particularly aimed at attenuating jerks and oscillations of the transmission when crossing said mechanical clearances.

Conventionally, a motor vehicle transmission comprises a primary shaft rotatably connected to the output shaft of the powertrain of the vehicle, and a secondary shaft fixed in rotation of wheels thereof, said driving wheels.

The primary shaft and the secondary shaft of the transmission drive each other by means of gear sets selectable by means of a gearbox.

In this system there are mechanical games causing jolts and oscillations during torque variations applied to the primary shaft and the secondary shaft.

An example of mechanical play of the transmission is illustrated in FIG. 1 in which a transmission gear E comprises a first gear R1, for example mounted on the primary shaft, and a second gear wheel R2 mounted on the secondary shaft. . The gear wheels R1, R2 mesh with each other, but a tooth of one wheel does not fully occupy the space between two teeth of the other wheel. There is therefore a mechanical play in the illustrated gear.

In the configuration in full lines of FIG. 1, the wheel R1 rotates the wheel R2 in the direction illustrated by the arrows F, a tooth of the wheel R1 of the primary shaft abutting on a surface A of a tooth of the wheel R2 of the secondary shaft.

During a change in the driving phase, such as a deceleration or a braking for example, the angular velocity of the wheel R1 decreases, and a tooth of the wheel R2 of the secondary shaft abuts on a surface B d ' a tooth of the wheel R1 of the primary shaft. This configuration is illustrated in phantom. However, as may be noted, during a transitional phase between these two configurations, due to the presence of the mechanical clearance, the two gear wheels R1 and R2 are no longer engaged and when the wheels R1 and R2 mesh again jolts may appear.

The transition from the configuration in solid lines to the configuration in phantom will be designated later "passage of the transmission game". The occurrence of such a passage depends on the torque applied to the transmission, that is to say that applied to the primary shaft by the powertrain and that applied to the secondary shaft by so-called motor wheels. A torque causing the passage of a mechanical play of the transmission will be referred to hereafter as "passing torque of a transmission set".

There are known torque control systems applied by the powertrain to the transmission to mitigate the disturbances (jolts and oscillations) caused by the passage of a transmission set.

These systems comprise means for acquiring the resistive torque applied to the driving wheels (torque due to friction) and means for acquiring a torque set point for the desired power unit of the driver. These systems also include an information processing unit which estimates transmission play passage torques and limit the variation of the torque setpoint delivered to the power unit when a passing torque is detected. Once the game has passed, the information processing unit applies a barycentric filter to converge to the desired torque set by the driver.

However, the estimate of transmission gears passage torques is based on the value of a torque applied by the powertrain to the transmission and reduced to the reference of the driving wheels. Such an estimate is generally of poor quality since there is a significant difference between the true value of a passing torque of a game and the estimated value thereof. It follows discontinuities in the calculated torque setpoint delivered to the power unit by the information processing unit such as slope breaks, which ultimately generate oscillations in the transmission.

The object of the present invention is to solve the aforementioned problem by proposing a system for controlling the operation of a motor-vehicle power unit which accurately estimates the torque transmission passages and calculates torque instructions for a smooth and continuous passage of the transmission sets.

For this purpose, the subject of the invention is a system for controlling the operation of a motor-drive unit controlled in motor vehicle torque, the power-train unit being connected to wheels of the vehicle for their drive through a transmission. having mechanical games, the system comprising:

means for acquiring a resistive torque exerted on said wheels;

means for acquiring a torque setpoint for the powertrain unit desired by the driver of the vehicle,

determination means, as a function of the acquired resistive torque, and the acquired torque setpoint, of an approval torque setpoint for the powertrain unit for attenuating disturbances caused by the passage of said mechanical games of the transmission, and

- Means for delivering the set torque regulation determined to the powertrain for the control thereof, characterized in that the means for determining the approval torque setpoint comprise:

first means for calculating a resistive torque brought back to the powertrain unit as a function of the acquired resistive torque, and for a zero torque transmitted by the transmission; and

second means for calculating said approval setpoint as a function of the resistive torque brought back to the calculated motor-propulsion unit.

According to particular embodiments of the invention:

the first means of calculating the resistive torque brought back to the powertrain are able to calculate it according to the relation:

where CAP _{nat is} is the resistive torque brought back to the power unit, C _ext is the acquired resistive torque, η is a reduction ratio of the transmission, JQMP wheel ^{ΘSt aΘ} inertia of the powertrain brought back to the wheels, and the _wheel is an inertia of the motor vehicle brought back to the wheels;

the second means for calculating the approval instruction are suitable for calculating it so that it exhibits an attenuated temporal variation during the passage of said mechanical clearances;

the second means for calculating the approval setpoint are suitable for calculating it so that it exhibits a substantially zero time variation during the passage of said mechanical clearances;

the second means for calculating the approval instruction are able to calculate it so that it continues the torque setpoint acquired for the powertrain unit from the driver, once said mechanical clearances have passed;

the second means for calculating the approval instruction are able to calculate it according to the following relation:

^ ap _ _ cns agr ^~ L J ⁿ * L ⁿ av + J * ap L ⁿ + J * ^ ap _ _ cns agr L ^{n ~~} J ¹ with

Y _av H ⁼ T _e - ^α L ⁿ UC _ap _ _cns L ⁿ J ~ C _ape _ _cns _ _agr [n - IJ] • C _ap _ _cns _ _agr [n - Ij - C _ape _ _nat _ _is [nj and

^Y ap H = ^T e • βf ⁿ ] • ( ^C ap _ cns H ^{~ C} _ap _ _cn _ _agr [n - 1]) where CAP _{cns agr} is the approval setpoint, Cap cns is the desired torque setpoint by the driver, CAP _{nat is} is the torque setpoint brought back to the powertrain, T _e is a predetermined sampling period, n is an nth sampling instant, and α and β are variable or constant parameters; and

- the second calculation means are adapted to dynamically select the parameters α and β depending on the difference between the target torque calculated accreditation CAP _C ns agr ^Θt ^'Θ torque reduced to the power train at _n CAP group is -

The invention will be better understood on reading the description which follows, given solely by way of example, and with reference to the accompanying drawings, in which: - Figure 1 is a schematic view of a transmission gear illustrating a transmission set, already described above;

- Figure 2 is a schematic view of a traction chain of a motor vehicle associated with a system according to the invention; and

FIG. 3 is a graph of curve illustrating torque instructions obtained according to a system of the state of the art and the system according to the invention.

In Figure 2, a power train of a motor vehicle is illustrated under the general reference 10.

This traction chain 10 comprises a motor-drive unit 12 (GMP) with a heat engine, controlled in torque and adapted to drive in rotation or to brake wheels 14, 16 of the vehicle through a transmission 18.

The transmission 18, delimited by a closed line in phantom, comprises a primary shaft and a secondary shaft (not shown), a disengaging member 20, a gearbox 22, a differential bridge 24 and gimbals 26, 28 connecting respectively the bridge 24 to the wheels 14, 16.

Of course, in the case of a hybrid engine GMP comprising a heat engine and an electric motor, the disengaging member is included in the GMP between the thermal and electrical engines, as is known per se.

The transmission 18 is conventional and therefore will not be described in more detail later. The transmission 18 has a certain number of mechanical clearances causing disturbances, such as jerks and oscillations, for torque values applied thereto by the wheels 14, 16 and the power unit 12, as has been previously described.

The traction chain 10 is associated with a system 30 for controlling the operation of the GMP 12 capable of determining, and delivering thereto, a torque setpoint, called "preventive approval", which has the effect, when it is applied by the GMP 12, to significantly attenuate the disturbances caused by the passage of transmission games.

The system 30 comprises a torque sensor 32 measuring the torque at the output of the GMP 12, a position sensor 34 measuring the position θ _p of the accelerator pedal of the vehicle, and a speed sensor 36 measuring the speed v of the vehicle.

The system 30 also comprises a preventive approval unit 38, delimited by a closed line in phantom, connected to the sensors 32, 34 and 36. This unit 38 comprises a module 40 connected to the position sensor 34 and determining a torque setpoint Cap cns for the GMP 12 as a function of the measured position θ _p of the accelerator pedal. This instruction Cap cns corresponds to the torque that wishes to apply the conductor to the primary shaft of the transmission 18 and is for example determined by evaluation of a map stored in the module 40.

The preventive approval unit 38 also comprises a module 42 for estimating the resistive torque C _ext exerted on the wheels 14, 18 because of the different friction they undergo.

The module 42 is connected to the torque sensor 32 and to the speed sensor 36 and estimates the resistive torque C _ext as follows:

Firstly, the module 42 calculates the theoretical torque C _{GMP wheel} ^ produced by the GMP at the wheels 14, 16 as a function of the measured torque, by the sensor 32 and a predetermined model of the transmission 18. Next, the module 42 calculates the theoretical resistive torque C _{ext ώ} exerted on the wheels 14, 16 as a function of the measured speed V of the vehicle and a predetermined model of the operation of the wheels 14, 16. From the theoretical resistive torque C _{ext ώ} and the theoretical torque C _{GMP wheel th} , the module 42 then determines a theoretical speed V _th of the vehicle, then determines an additional resistive torque C _{ext ad} exerted on the wheels as a function of the difference between the theoretical speed V _th calculated and the speed real measured v of the vehicle.

The resistive torque C _ext exerted on the wheels 14, 16 is then calculated by the module 42 as the sum of the theoretical resistive torque C _{ext ώ} and the additional resistive torque C _{ext ad} . The calculation of the additional resistive torque C _{ext ad} thus makes it possible to take into account uncertainties on the model of operation of the wheels 14, 16, as uncertainties on the slope of the road and the speed and direction of the wind for example.

The preventive approval unit 38 also comprises a calculation module 44 connected to the module 42 for calculating the resistive torque C _ext . The module 44 is able to calculate a CAP value _{nat is} of resistive torque brought back to the GMP 12 corresponding to a passing torque of a transmission set.

More particularly, a pair C _{GMP AP} applied to the wheels 14, 16 by the GMP 12 and brought back to the primary shaft of the transmission 18 can be modeled according to the relation:

where C _traas is the torque transmitted by the transmission at the secondary shaft thereof, JVEH wheel ^ΘSt 'inertia of the vehicle brought back to the wheels 14, 16, JQMP wheel ^ΘSt ' inertia of the GMP 12 brought back to the wheels 14, 16 , and η is a reduction factor of the transmission depending on the engaged ratio of the gearbox and a reduction factor of the differential bridge 24 of the transmission 18.

When passing a transmission set, the torque C ^ s is momentarily zero. By referring for example again to the example of the game of FIG. 1, when the toothed wheels R1 and R2 are between the configurations in solid lines and phantom lines, the primary shaft and the secondary shaft of the transmission are disconnected so that the transmitted torque

Ctrans is zero.

The module 44 determines the resistive torque CAP _{nat is} reduced to

GMP 12 corresponding to a passing torque of a mechanical game according to the relation:

with JQMP wheel ^Θ t ^J VEH wheel having predetermined values. The passing torque of a transmission set is therefore accurately estimated since it corresponds to a zero torque C ^ ₁₀₁₅ transmitted by the transmission which characterizes the passage of the transmission sets.

Finally, the preventive approval unit 38 comprises a module 46 for calculating a torque set CAP _{cns agr} of preventive approval. This module

46 is connected to the modules 40 and 44, calculates, and delivers to the GMP 12 for its command, the instruction CAP _{cns agr} according to the following numerical relation:

Cape cns _ _ agr L ⁿ ^J ⁿ J * L av ^~ * ^~ * ap L ⁿ J ^~ * ^~ ap cns _ _ L ⁿ agr ^~~ IJ with

Yav H ⁼ T _e - ^α L ⁿ UCap _ cns L ⁿ J ^~ C _ap _ _cs _ _agr [n - IJj • C _ap _ _cns _ agr L ^{n ~} IJ ^~ C _ap _ _nat _ _is [n_ | and

Y _ap W = T _e . β [n]. (c _ap _ _cns [n] -C _ap _ _{cns agr} [n -l])

where T _e is a predetermined sampling period, is the nth sampling instant, and α and β are variable parameters.

Respective values of the parameters α and β at the instant n are selected by the module 46 as a function of the value at the instant n of the difference C _{ap C} ns [ ⁿ ] ~ C _{ap nat} is M - The parameters α and β are for example tabulated in the module 46 according to the values of this difference Alternatively, the parameters α and β are constant.

The component Y _av has the effect of attenuating the temporal variations of the torque setpoint delivered to the GMP 12 just before crossing a transmission set. Advantageously, the time derivative of the torque set CAP _C ns agr delivered to the GMP is lower in absolute value than the time derivative of the torque set point C _A p _C ns delivered by the module 40, and preferably this time derivative CAP _C ns agr ^ΘSt substantially zero during the passage of these games.

The component Y _ap has the effect of further, and quickly converge to the CAP _C ns desired torque desired by the driver of the vehicle once the game transmission past.

FIG. 3 is a graph illustrating the preventive authorization instruction obtained by the system according to the invention (curve A), that obtained by a system of the state of the art (curve B), the desired torque set by the driver (curve C) and a real value of a passing torque of a transmission set (curve D). As can be seen, the torque setpoint calculated by the system according to the invention takes effect at the level of the game's passing torque, unlike that of the state of the art, while being regular, c that is, without presenting the discontinuities of that of the state of the art.

Claims

1. System (30) for controlling the operation of a power unit (12) controlled in motor vehicle torque, the power unit (12) being connected to wheels of the vehicle (14, 16) for their training through a transmission (18) having mechanical clearances, the system comprising:

- means (32, 36, 42) for acquiring a resistive torque exerted on said wheels (14, 16);

means (34, 40) for acquiring a torque setpoint for the powertrain (12) desired by the driver of the vehicle,

means (38) for determining, as a function of the acquired resistive torque, and the acquired torque setpoint, an approval torque setpoint for the powertrain unit (12) intended to attenuate disturbances caused by the passing said mechanical games of the transmission (18), and

- Means (38) for delivering the set torque command determined to the powertrain (12) for the control thereof, characterized in that the means (38) for determining the torque setpoint d approval include:

first means (44) for calculating a resistive torque brought back to the power unit (12) as a function of the acquired resistive torque, and for a zero torque transmitted by the transmission (18); and

second means (46) for calculating said approval instruction as a function of resistive torque brought back to the calculated powertrain unit.

2. System according to claim 1, characterized in that the first means (44) for calculating the resistive torque brought to the power unit (12) are suitable for calculating it according to the relation:

where CAP _{nat is} is the resistive torque brought back to the power unit (12), C _ext is the acquired resistive torque, η is a reduction ratio of the transmission (18), JQMP wheel ^{ΘSt a group} inertia ^Θ motor-propeller (12) brought back to the wheels (14, 16), and J _{VEH wheel} is an inertia of the motor vehicle brought back to the wheels (14, 16).

3. System according to claim 1 or 2, characterized in that the second means (46) for calculating the approval setpoint are adapted to calculate it so that it has a temporal variation attenuated during the passage of said mechanical games .

4. System according to claim 3, characterized in that the second means (46) for calculating the approval setpoint are adapted to calculate it so that it has a substantially zero time variation during the passage of said mechanical clearances.

5. System according to any one of the preceding claims, characterized in that the second means (46) for calculating the instruction of approval are able to calculate it to continue the torque setpoint acquired for the group motor-propeller (12) from the driver, once said mechanical games past.

6. System according to any one of the preceding claims, characterized in that the second means (46) for calculating the instruction of approval are able to calculate it according to the following relation:

^C ap _ cns _ agr H = ^Y av H + ^Y ap M + ^C _ap _ cns _ agr [ ^{n ~ 1} J with

^Y av L ⁿ J ⁼ T _e - ^α L ⁿ Ucap _ cns L ⁿ J ^~ _C p _ cns _ agr L ^{n ~} YJI • C _ap _ _cns _ _GF [n - IJ - C _ap _ _nat _ _is [ nj and

^Y ap H = ^T e • βM • (C _ap _ cns M ^{~ C} _ap _ _C ns _ agr [ ^{n ~ 1} J) where CAP _{cns agr} is the approval setpoint, Cap cns is the torque setpoint desired by the driver, CAP _{nat is} is the torque setpoint brought back to the powertrain, T _e is a predetermined sampling period, n is an nth sampling instant, and α and β are variable or constant parameters.

7. System according to claim 6, characterized in that the second means (46) of calculation are adapted to dynamically select the parameters α and β as a function of the difference between the torque setpoint. accredited CAP CAP _{cns agr} and the torque brought back to the power unit CAP _nat .