DE102008026509A1 - Method for determining torque transmitted over drive train of motor vehicle, involves estimating and utilizing failure model to correct estimated torque, where mechanical model is influenced by failure model - Google Patents

Abstract

The method involves measuring initial and output speeds of a section of a drive train (10), and inputting the speeds into an observer, which observes a condition of the drive train section. The drive train section is represented as a torsionally flexible shaft with Hookian constant, using a control technical mechanical model. Torque transmitted over the drive train section is estimated from a rotational status of the shaft in the observer. A failure model is estimated and utilized to correct the estimated torque, where the mechanical model is influenced by the failure model. An independent claim is also included for a control technical observer for controlling a drive train of a motor vehicle.

Description

The The present invention relates to a method for determining the above transmit a drive train of a motor vehicle Torque, where the input speed and the output speed measured a section of the drive train and then be entered into a control technical observer who observed the state of the drive section control technology, wherein the observer a control engineering mechanical model of the Powertrain section includes that the drive train section represented as a torsionally flexible shaft with a torsional rigidity, and wherein from the state of rotation of the shaft in the observer the transmitted through the drive train section Torque is estimated.

Further the invention relates to a control technical observer to Use in a control of a drive train of a motor vehicle, with a mechanical control model of a drive train section, the drivetrain section as a torsionally elastic shaft with a Torsional stiffness represents where the input speed and measured the output speed of the drive train section and then entered into the observer, the observed the state of the drive train section control technology.

such Methods and devices are used in a drive train to estimate the torque transmitted to a motor vehicle.

Out AT Automation Technology 55 (2007) 3, pages 127-135 A method is known for estimating the torque transmitted in a drive train by means of a control observer, in which an engine speed and a wheel speed are measured and the moments of inertia of the transmission and the wheel side mass and the Hook'sche constant of the drive train and various damping parameters of the transmission and the Wheels are assumed to be constant and familiar.

adversely in the known method it is that the material parameters of the Drivetrain are difficult to determine and are in operation influence each other and can vary.

It is therefore the object of the present invention, a universal Method and a universal device for determining of the transmitted via a drive train of a motor vehicle To provide torque.

These Task is according to a first aspect of the invention solved in the aforementioned method in that the observer implies that an error model affects the mechanics model, the error model is also appreciated and used will correct the estimated torque.

Further The above object is achieved according to a second aspect solved by the invention in the method mentioned, characterized that of an input side drive motor in the drive train introduced driving torque is measured, and wherein the torsional stiffness in the observer using the measured drive torque is appreciated.

Further the above object is achieved by an aforementioned control technical observer, wherein from the state of rotation of the Wave in the observer transmitted through the powertrain section Torque is estimated, and wherein the observer includes that an error model influences the mechanical model, with the error model also valued and used, the estimated Correct torque.

advantage the method according to the invention is that the transmitted torque under consideration the error model is estimated and thus also time delays the measured values are taken into account in estimating the torque.

Farther This procedure can be independent of the powertrain used and a gear engaged, since the torsional stiffness of the drive train section is estimated by the observer becomes.

advantage of the control technical observer is that all disturbances be estimated and to control the powertrain be available.

The The above object is thus completely solved.

In a preferred embodiment of the method considered the error model that is a change in input speed delayed due to the resulting rotation of the shaft affects the output speed.

Thereby can take into account the torsion-springing effect of the drive train become.

In a preferred embodiment of the method, the error model takes into account that measurements of the input speed and the Aus speed does not match each other.

Thereby It is possible to get a time offset of readings due to of data transfer delays occurs consider.

Further it is particularly preferred if the error model is the temporal Delay as a differential delay considered.

Thereby can speed differences between input and output speed be modeled particularly accurately because of a differential delay the torsional elastic effect of the drive train corresponds.

there it is particularly preferred if the differential delay is modeled by a PT1 element.

In a preferred embodiment of the method is Mechanic model a single-mass oscillator that has a mass which is connected to a torsionally elastic spring whose torsional stiffness represents the torsional stiffness of the shaft.

Thereby the drive train can be modeled very easily, since a complex modeling of a wheel-side mass is eliminated.

In an alternative embodiment of the method is mechanic model used a two-mass oscillator, the two masses having, which are connected by a torsionally elastic spring whose Torsional stiffness represents the torsional stiffness of the shaft.

By this mechanical model can be the transmitted moment and model the error model very precisely.

Farther it is preferred if between the observed drive train section and the drive motor a clutch is present, the estimate the torsional rigidity occurs only when the clutch is closed is.

Thereby can the output from the drive motor torque than that in the Powertrain section introduced drive torque used become.

there it is preferred if for the determination of the transmitted Torque in phases in which the clutch is opened is a last estimated estimate for the Torsional stiffness is used.

Thereby is a more accurate estimate of torsional stiffness Also available in the phases where the torsional stiffness can not be appreciated.

In a preferred embodiment of the method is the Input speed the speed of an output shaft of a transmission, that between the driveline section and a drive motor is arranged.

Thereby can an error z. B. be excluded by lots of the transmission.

In a preferred embodiment of the method is the Output Speed The speed of driven drivetrain wheels.

Thereby can all influences until traction transmission of the wheels for the estimation of the fault model be taken into account.

Farther it is preferable to have a drive train for a motor vehicle, with a drive motor, a clutch, a transmission, a cardan shaft, driven wheels and a control device with a control technical observer according to the invention equip.

Thereby is the control-technical observer special to use efficiently in a motor vehicle.

Farther It is preferable if the fault model is loose in the powertrain considered.

Thereby can influences the drivetrain on the torque transmission be taken very precisely.

Farther it is preferred if the error model is gear-dependent parameters considered.

Thereby can the different influences of different Gear stages taken into account for the control of the drive train become.

Farther it is preferred if nonlinearities of the drive train be taken into account in the error model.

Thereby can the torque transmission in the drive train model very precisely.

It it is understood that the above and the following yet to be explained features not only in each case specified combination, but also in other combinations or can be used in isolation, without the scope of the present To leave invention.

Embodiments of the invention are in represented in the drawing and are explained in more detail in the following description. Show it:

1 a schematic representation of a drive train of a motor vehicle;

2 a control mechanical model of a drive train section;

3 a block diagram of a controlled system with an observer;

4 a block diagram for controlling a powertrain with torque estimation;

5 a block diagram for explaining the operation of the observer with the clutch closed and opened.

In 1 is a powertrain of a motor vehicle generally with 10 designated.

The powertrain 10 has a drive 12 up, over a crankshaft 14 with a dual-clutch transmission 16 connected is. The dual-clutch transmission 16 has two couplings 18 . 19 and two partial transmissions 22 . 24 on. The dual-clutch transmission 16 is via a propshaft 26 and a differential 28 with two transverse waves 30 . 32 connected. The transverse waves 30 . 32 are each with a drive wheel 34 . 36 connected.

The drive 12 generates an engine torque 38 That's about the crankshaft 14 to the dual-clutch transmission 16 is transmitted. The crankshaft 14 turns at an engine speed 40 , The engine speed 40 gets on the crankshaft 14 detected by a tachometer, not shown. The engine torque 38 and the engine speed 40 be to the couplings 18 . 19 of the dual-clutch transmission 16 transfer. By mutual closing or opening of the couplings 18 . 19 become the engine torque 38 and the engine speed 40 via one of the transmission input shafts 20 . 21 to each one of the partial transmission 22 . 24 transfer.

The transmission input shafts 20 . 21 each turn at a transmission input speed 46 . 48 and each transmit a transmission input torque 42 . 44 on each one of the partial transmission 22 . 24 ,

The partial transmissions 22 . 24 translate the engine speed 40 according to an engaged gear stage, and the translated engine speed 40 and the translated engine torque 38 be to the cardan shaft 26 transfer. The cardan shaft 26 turns at a transmission speed 48 , The transmission speed 48 is detected by means of a tachometer, not shown. At the propshaft 46 is still a gear torque 49 at. The cardan shaft 26 transmits the gear torque 49 and the transmission speed 48 about the differential 28 and the transverse waves 30 . 32 on the drive wheels 34 . 36 , The drive wheels 34 . 36 each have a wheel speed 50 . 52 and one wheel torque each 54 . 56 on. The wheel speed 50 . 52 is detected by a respective tachometer, not shown. The wheel speed 50 . 52 and that on the drive wheels 34 . 36 fitting wheel torque 54 . 56 deviate from a mathematical expected value, since these values are affected by disturbance variables such. B. twisting or loose or game can be influenced.

The drive train shown here 10 is to be understood as general and general. It will be understood that the present invention is not limited to a driveline having a dual clutch transmission and a driven axle, but may also be used for simple transmissions and four-wheel drive vehicles and hybrid powertrains.

In 2 an embodiment of a control engineering mechanical model of a drive train section is shown, which generally with 60 is designated. The mechanic model 60 consists of a transmission-side mass 62 , a wheel-side mass 64 and an elastic shaft 66 , The transmission side mass 62 is with one side of the elastic shaft 66 connected, and another side of the elastic shaft 66 is with the wheel-side mass 64 connected. The transmission side mass 62 has an inertia moment 68 on and rotates with the transmission speed 48 , In the moment of inertia 68 the gearbox ground 62 are the moments of inertia of a part of the respective clutch 18 . 19 , the respective sub-transmission 22 . 24 and the cardan shaft 26 summarized. The wheel-side mass 64 has an inertia moment 70 on and rotates with the respective wheel speed 50 . 52 , At the gearbox ground 62 is the gear torque 49 on, and on the wheel-side mass 64 is the wheel torque 54 . 56 at. In the moment of inertia 70 are the moments of inertia of the differential 28 , the cross waves 30 . 32 and the drive wheels 34 . 36 summarized. The elastic wave 66 has a Hook's constant 72 (c), a twist 74 (Ψ) and a twisting moment 76 (T _Ψ ). The Hook's constant 72 the elastic wave 66 corresponds to the rigidity of the drive train, the twisting 74 corresponds to the rotation of the drive train by the applied gear torque 49 and the applied wheel torque 54 . 56 , and the twisting moment 76 corresponds to the moment in the drive train section. The twisting moment 76 results from the multiplication of the twist 74 with the Hook's constant 72 of the powertrain. The Hook's constant 72 or the rigidity of the drive train section is dependent on the engaged gear and is non-linear.

The mechanic model 60 serve the transmission speed 48 and the wheel speed 50 . 52 as an input quantity, which are each detected by tachometers. Furthermore, additionally the gear torque 48 serve as a measured input. Based on the mechanics model 60 With the input variables, various influencing variables of the drive train section including an error model are estimated in order to determine an actual torque in the drive train section.

An alternative embodiment of the mechanical model 60 differs from the in 2 illustrated mechanical model 60 no wheel bearing mass 64 on, but only the transmission-side mass 62 and the associated elastic wave 66 , Notwithstanding the in 2 illustrated embodiment is the wheel torque 54 . 56 directly to a free end of the elastic shaft, that of the transmission-side mass 62 opposite. The free end of the elastic shaft rotates with the wheel speed 50 . 52 ,

This embodiment of the mechanical model 60 has opposite the in 2 illustrated mechanical model 60 the advantage of having a complex modeling of the wheel-side mass 64 and the associated moment of inertia 70 eliminates the need for modeling, thereby accelerating powertrain control.

The error model also considers lots, gear-dependent parameters and nonlinearities in the powertrain 10 may occur.

In 3 is a control block diagram of a drive train section with observers shown. The driveline section 80 forms a controlled system with an input variable 82 or manipulated variable (u) and an output variable 84 or controlled variable (y), wherein the drive train section 80 a powertrain condition 86 as system state.

Parallel to the controlled system is a control technical observer 88 connected. The Observer 88 indicates input variables as input variables 82 of the powertrain section 80 and the output size 84 of the powertrain section 80 on. As the output size gives the observer 88 a model condition 89 (x ^) off. The Observer 88 has a model 90 , a proofreader 92 and a subtractor 94 on. The model 90 takes the model state 89 as system state. Input quantities of the model are the input quantity 82 of the powertrain section 80 and a corrector output 96 , The model 90 gives a model output 98 (y ^) and the model state 89 (x ^) off. The model output 98 and the output size 84 serve as the input of the subtractor 94 , The subtractor 94 gives a difference 100 out to the proofreader 92 serves as input size.

As the input 82 serve the gear torque 49 and the wheel speed 50 . 52 , The powertrain condition 86 is formed from the transmission speed 48 , the twist 74 and the error model. The output size 84 of the powertrain section 80 is formed by the transmission speed 48 and a fictitious second output that is zero. To the powertrain condition 86 to estimate or estimate is the drive train section 80 the Observer 88 connected in parallel. The model 90 forms the mechanic model 60 out 2 according to control technology and determined from the input variable 82 that by the gearbox speed 48 , the twist 74 and the error model is formed, the model output 98 , The deviation of the model output 98 from the initial size 84 of the powertrain section 80 is through the subtractor 94 determined and as the difference 100 to the proofreader 92 given. The proofreader 92 gives the model 90 the corrector output 96 a, based on the model 90 the model state 89 or at least one of the model parameters included in 2 are shown corrected. After this correction gives the model 90 a modified model output 98 to the subtractor 94 out. This is the model state 89 continuously corrected until the difference 100 is zero and no correction is needed. If the difference 100 is zero, corresponds to the model state 89 the powertrain condition 86 , The model condition 89 is from the model 90 output and can be used to control the powertrain 10 or for regulating the drive train section 80 be used.

By doing that, the observer 88 the model state 89 which is continuously adjusted so that the model output 98 and the output size 84 are identical, the powertrain condition 86 that is the Hook's constant 72 , the twist 74 , the twisting moment 76 and the error model can be estimated.

By doing that, the model 90 the mechanic model 66 and the error model maps are all in the mechanics model 66 and the parameter considered by the error model also by the observer 88 considered.

at the moment estimate generally becomes a time delay of the measured values. Such a time delay can occur due to data acquisition delays, data processing delays and data transfer delays.

In 4 is a schematic block diagram for controlling the powertrain 80 by means of egg ner torque estimate shown.

The block diagram shows a controller 102 with a reference variable 104 (w) as input size and an estimated moment 106 , which serves as another input size. The regulator 102 has an output size that is the input size 82 of the powertrain section 80 forms. The driveline section 80 gives the output size 84 out, a moment estimate 108 serves as input size. As a further input quantity of the moment estimate 108 serves the input size 82 , The moment estimate 108 instructs the observer 88 on and other components to calculate the estimated moment 106 that of the moment estimate 108 output and the regulator 102 is entered.

The regulator 102 gives based on the reference variable 104 and the estimated moment 106 that of the powertrain 80 transmitted torque including the error model corresponds to the input variable 82 or the manipulated variable of the drive train 80 off, by the transmission input torque 42 . 44 and the wheel speed 50 . 52 is formed. The regulation is preferably carried out by adjusting the clutch pressure of one of the clutches 18 . 19 , This can change the output size 84 or the controlled variable, which is the transmission speed 48 forms, be regulated.

In 5 is the principal operation of the observer 88 . 88 ' generally shown when the clutch is closed and open.

With the clutch closed 18 . 19 the observer gets 88 the input quantities motor torque 38 , Wheel speed 50 . 52 and transmission speed 48 , As the output size gives the observer 88 in this case the estimated moment 106 and the Hook's constant 72 indicating the rigidity of the drivetrain section 80 forms, off.

In a situation where one of the clutches 18 . 19 is completely closed, corresponds to the engine torque 38 exactly the gear torque 49 and thus can be used for estimating the estimated moment 106 be used. The engine torque 38 can be determined for example via the engine control or measured on the crankshaft. In this case, that the gear torque 49 is known, both the estimated moment 106 as well as the Hook's constant 72 to be appreciated.

If none of the couplings 18 . 19 is completely closed, the gear torque 49 can not be determined. For this case, the observer 88 ' from the wheel speed 50 . 52 and the transmission speed 48 just the estimated moment 106 determine. As a further input size serves the previously with the clutch closed by the observer 88 estimated Hook's constant 72 , The Hook's constant 72 becomes the watcher 88 ' during a gear change or when the clutch is slipping from the last estimate with the clutch engaged 18 . 19 by the observer 88 provided.

Thereby can always be with the actual moment in the drive train high accuracy.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited non-patent literature

• - AT Automation Technology 55 (2007) 3, pages 127-135 [0004]

Claims (16)

Method for determining the drive train ( 10 ) of a motor vehicle transmitted torque, wherein the input speed and the output speed of a portion of the drive train ( 10 ) and then in a control technical observer ( 88 ), which observes the state of the drive train section in terms of regulation, wherein the observer ( 88 ) a control engineering model ( 60 ) of the drivetrain section comprising the drivetrain section as a torsionally flexible shaft with a torsional rigidity ( 72 ), and wherein from the state of rotation of the shaft in the observer ( 88 ) the torque transmitted via the drive train section is estimated, characterized in that the observer ( 88 ) implies that an error model is the mechanics model ( 60 ), where the error model is also estimated and used to correct the estimated torque. Method according to claim 1, characterized in that that the error model takes into account that there is a change the input speed due to the resulting rotation the wave delayed affects the output speed. Method according to claim 1 or 2, characterized that the error model takes into account that measurements of Input speed and the output speed not in time to each other fit. Method according to claim 2, characterized in that the mechanical model ( 60 ) considers the delay as a differential delay. Method according to one of claims 1 to 4, characterized in that the mechanical model ( 60 ) is a one-shot oscillator that has a mass ( 62 ), which with a torsionally elastic spring ( 66 ) whose torsional rigidity is the torsional rigidity ( 72 ) represents the wave. Method according to one of claims 1 to 4, characterized in that the mechanical model ( 60 ) is a two mass oscillator, the two masses ( 62 . 64 ), which by a torsionally elastic spring ( 66 ) whose torsional rigidity is the torsional rigidity ( 72 ) represents the wave. Method according to one of claims 1 to 6 or according to the preamble of claim 1, characterized in that by an input-side drive motor ( 12 ) in the drive train ( 10 ) introduced drive torque ( 38 ) and the torsional rigidity ( 72 ) in the observer ( 88 ) using the measured drive torque ( 38 ) is estimated. A method according to claim 7, characterized in that between the observed drive train section and the drive motor ( 12 ) a coupling ( 18 . 19 ) and the estimation of torsional rigidity ( 72 ) only occurs when the clutch ( 18 . 19 ) closed is. A method according to claim 8, characterized in that for the determination of the transmitted torque in phases in which the clutch ( 18 . 19 ), a last estimated value for torsional stiffness ( 72 ) is used. Method according to one of claims 1 to 9, characterized in that the input speed is the speed of an output shaft of a transmission, which between the drive train portion and a drive motor ( 12 ) is arranged. Method according to one of claims 1 to 10, characterized in that the output speed, the speed ( 50 . 52 ) powered wheels ( 34 . 36 ) of the drive train ( 10 ). Method according to one of claims 1 to 11, characterized in that the fault model lots in the drive train ( 10 ) considered. Method according to one of claims 1 to 12, characterized in that the fault model gear ratio dependencies considered in the transmission. Method according to one of claims 1 to 13, characterized in that the fault model nonlinearities of the drive train ( 10 ) considered. Regulatory observer for use in the control of a drive train ( 10 ) of a motor vehicle, with a control engineering mechanical model ( 60 ) a drive train section, which the drive train section as a torsionally elastic shaft with a torsional rigidity ( 72 ), wherein the input speed and the output speed of the drive train section are measured and then in the observer ( 88 ), which observes the state of the drive train section in terms of control engineering, characterized in that from the state of rotation of the shaft in the observer ( 88 ) the torque transmitted via the drive train section is estimated, and wherein the observer ( 88 ) implies that an error model is the mechanics model ( 60 ), wherein the error model is also estimated and used to correct the estimated torque. Drive train for a motor vehicle, with a drive motor ( 12 ), a coupling ( 18 . 19 ), a transmission ( 22 . 24 ), a cardan shaft ( 26 ), driven wheels ( 34 . 36 ) and a control device with a control-technical observer ( 88 ) according to claim 15.