DE102005039758A1 - Method for operating motor vehicle internal combustion (IC) engine, involves measuring disturbance torque of engine, then determining servo torque for engine control based on disturbance and target torques - Google Patents

Abstract

The variable disturbance torque of the engine, which is a function of the engine speed, is measured. Variable disturbances include head wind, road gradient, and other factors. The servo torque for engine control is determined based on the disturbance and target torques. The servo torque may include a loss torque corresponding to calculable variable disturbances and added to the target torque. An independent claim is also included for a device for operating an IC engine.

Description

The The present invention relates to a method for operating a Internal combustion engine, in which a speed of the internal combustion engine dependent on is controlled by a predetermined target speed, and in which dependence a control difference between the speed and the target speed by means of a control element, a desired torque for controlling the internal combustion engine is determined.

The The present invention further relates to an apparatus for operating an internal combustion engine according to the preamble of claim 9.

method and devices of this type are known and commonly based on a PI (Proportional Integral) controller trained regulator. Due to the integral member of the at conventional systems inserted PI-Regelglieds becomes in the case of a strong change the reference variable and one associated large Control difference for a subsequent stationary Regulation unfavorable Start value built in the integrator of the integral term, so that it comes to a pronounced overshoot.

regulating members without such an integral term, although have a lower overshoot but they have a non-vanishing state in a steady state Control difference, which is also undesirable.

Accordingly, it is Object of the present invention, a method and an apparatus of the type mentioned above to improve that overshoot in case of a change the reference variable is reduced becomes and at the same time in a stationary state a disappearing Control difference is achievable.

at a method according to the preamble of claim 1 is this task according to the invention thereby solved, that a disturbing moment, which represents, in particular, immeasurable disturbances, is estimated, and that a used for driving the internal combustion engine Actuating torque in dependence of Nominal torque and the disturbance torque is determined.

Advantages of invention

By the estimation of the invention disturbance torque can otherwise immeasurable disturbances, the can still affect the speed of the internal combustion engine and in conventional methods for example, a non-disappearing control difference in one stationary Cause condition in a speed controller of the internal combustion engine considered become. Thus, when using the operating method according to the invention a permanent control difference in a stationary state can be avoided.

When non-measurable disturbances in the sense The present invention considers all influencing factors which can influence the speed of the internal combustion engine and at least not directly from other operating variables of the internal combustion engine are derivable. In particular, a roadway slope and / or affect Headwind and the like as disturbances on the speed control off.

All in all is achieved by the operating method according to the invention an improvement in leadership behavior a speed control opposite usual Achieved systems.

When another solution The object of the present invention is a device according to claim 9 indicated.

advantageous Embodiments of the invention are the subject of the dependent claims.

Further advantages, features and details will become apparent from the following description in which, with reference to the drawings, various embodiments of the invention are shown. The features mentioned in the claims and in the description can each individually for themselves or be essential to the invention in any combination.

drawing

In the drawing shows:

1 FIG. 3 is a block diagram showing the signal flow in a first embodiment of the method according to the invention, FIG.

2 a block diagram illustrating a further embodiment of the method according to the invention,

3 an embodiment of the device according to the invention, and

4 an embodiment of a model according to the invention.

description the embodiments

1 shows a block diagram illustrating the signal flow in a first embodiment of the speed controller according to the invention 100 indicates. How out 1 becomes apparent to the speed controller 100 On the input side, a control difference e is supplied, in which it is a difference between a predefinable setpoint speed n_soll as a reference variable and the actual, metrologically detected speed n_BKM of an internal combustion engine 10 ( 3 ).

The speed controller 100 has a trained as a proportional element control element R, the control difference e in a target torque M_soll for controlling the internal combustion engine 10 transformed in the block diagram according to. 3 in the form of the block 10 is shown. In contrast to conventional speed regulators with trained as PI controller control elements, the speed controller according to the invention 100 Even with large changes in the reference variable n_soll only a relatively low overshoot, because temporarily applied to the control element R large control differences e are not stored in an integral term, as is the case in the prior art. That is, according to the invention is by waiving an integral element in the speed controller 100 an improved leadership behavior especially in transient processes achieved.

When controlling a controlled system with integral behavior (vehicle) by means of a PI controller, an I ₂ structure occurs in a closed circuit. The system is thus structurally unstable. The controller structure with torque estimation has no structural instability and thus avoids the tendency to low-frequency vibrations.

The speed controller according to the invention 100 is preferably within a controller 20 that implements the internal combustion engine 10 with in 3 through the arrow 20a symbolized control signals applied, and the - as by the arrow 20b symbolizes - input variables 20b be supplied. Particularly preferred is an implementation of the speed controller 100 in the form of one in a memory of the controller 20 stored program codes.

At the drive signals 20a may be, for example, the already described desired torque M_soll ( 1 ) or preferably by a derived therefrom size such as the control torque M_stell act. With the input variables 20b ( 3 ) may be, for example, the rotational speed n_BKM as well as further operating variables of the internal combustion engine 10 act.

The following is the operation of the speed controller according to the invention 100 out 1 described in more detail.

How out 1 can be seen, to the target torque M_soll obtained by means of the control element R in the adder 30a adds a known loss moment M_vb determined in the block labeled M_vb 'and, for example, in the controller 20 known performance requirements of ancillary equipment such as an air conditioner represents. At the output of the adder 30a Consequently, a setpoint torque M_setpoint compensated for the known loss moment M_vb is obtained. This way will be safe provided that known power requirements of consumers or other known loss moments, such as those caused for example due to friction effects in a transmission or the like, in the control of the speed n_BKM of the internal combustion engine 10 be taken into account and thus can not lead to an uncontrolled lowering of the speed n_BKM.

To the compensated setpoint torque M_soll 'an inventively estimated disturbance torque M_stör is added, whereby at the output of the adder 30b the desired torque M_soll '' is obtained. The disturbance torque M_stör in particular represents non-measurable disturbance variables which are related to the rotational speed n_BKM of the internal combustion engine 10 affect and thus the leadership behavior of the speed controller 100 can affect. The non-measurable disturbances are, for example, a road gradient or other disturbances that in one of the internal combustion engine 10 attacking disturbance torque M_stör can be transformed.

The inventive consideration of these disturbances in the form of the disturbance torque M_stör allows - analogous to the known loss moment M_vb - an improvement of the leadership behavior of the speed controller 100 and in particular also makes it possible to achieve a vanishing control difference e in a stationary state, which is not possible with conventional speed controllers without an integral element.

The nominal torque M_soll '' compensated by the known loss moment M_vb and the disturbance torque M_stör, which is determined according to FIG 1 at an output of the adder 30b is received, a moment coordinator MK is supplied, which makes prioritizing torque requests of different systems such as an accelerator pedal position or a speed limit in a known manner and not described in detail here way.

Accordingly, the actuating torque M_stell, which finally leads to the activation of the internal combustion engine, is applied to an output of torque coordinator MK 10 ( 3 ) is used. The internal combustion engine 10 itself is in the speed controller 100 gem. 1 is taken into account by a transmission element G which represents its transmission properties and has at its output the rotational speed n_BKM which is dependent on the actuating torque M_set supplied to it. In addition to the internal combustion engine 10 can by the transfer member G and the influence of others, with the internal combustion engine 10 Coupled and not shown systems are taken into account.

The disturbance torque M_stör already described is inventively from the actual, metrologically detectable speed n_BKM the internal combustion engine 10 determined by means of a transmission song G 'whose transfer function is preferably inverse to the transfer function of the internal combustion engine 10 As a simplification, the transfer function of the transfer element G 'can also be chosen such that it approximates the transfer function G inverse transfer function.

How out 1 As can be seen, the transmission element G 'transforms the rotational speed n_BKM supplied to it into the estimated torque M_ Schätz. This estimated torque M_ estimation represents a torque available for acceleration, which depends on the disturbances already described, such as a road gradient.

According to the invention, the disturbance torque M_stör results as the difference between a control torque M_set 'and the estimated torque M_account reduced by the known loss moment M_vb, ie M_stör = M_stell-M_vb-M_schätz. The disturbance torque M_stör is as described above via the adder 30b the desired torque M_soll 'added, so that a required, for example, at a strong road gradient to maintain the speed n_BKM increase the target torque M_soll''in this way can be achieved.

There it is at a the transmission link G 'underlying Model usually in comparison to the transmission link G is a simplified model can, in a further embodiment of the present invention, the transfer member G 'supplied speed n_BKM first a filtering (not shown) are subjected, so that the transmission member G 'only ones Frequency components of the speed signal n_BKM be supplied for the relevant model valid is.

Likewise, the adjusting torque M_set 'and / or the disturbance torque M_stor reduced by the known loss moment M_vb can also be subjected to a corresponding filtering (not shown), in particular to a dynamic stability of the speed controller according to the invention 100 sure. For filtering, filters of the first or higher order can be used in a manner known per se.

The inventive estimation of the disturbance torque M_stör by means of the transmission element G 'can advantageously also not directly measurable disturbances such as a road gradient in the speed control in the control unit 20 be taken into account. In this way, the use according to the invention of a control element R embodied as a proportional element is possible which, even with large changes in the reference variable n_setpoint, exhibits low overshoot behavior in comparison to conventional speed controllers comprising PI controllers. A non-disappearing control difference e in a stationary state existing with proportional governors based on proportional elements is excluded according to the invention by the consideration of the disturbance torque M_stör, which is the control path in the described manner via the adder 30b is supplied. That is, the speed controller according to the invention 100 allows in a steady state to achieve a vanishing control difference e, even without the use of an integral term.

Since the estimation according to the invention of the disturbance variables, which leads to disturbance torque M_stör, is carried out continuously, it is possible to take into account in general the time-variant disturbance variables both in a stationary state and when a driver request torque is applied and in transient processes, whereby in all operating situations of the speed controller 100 a comparison with conventional systems improved leadership behavior is achieved.

Simulations have shown that in a temporary increase of the control torque M_stell, for example in the form of a rectangular function with predefinable pulse width, for example, represents a change in the driver's desired torque, the speed n_BKM in the speed controller according to the invention 100 Matches much faster to the target speed n_soll than a conventional speed controller with an integral element. In the speed controller according to the invention 100 the transient was completed under the above conditions already after about 17s, while in the transient of the conventional speed controller even after about 100s still a significant overshoot could be found. The use according to the invention of a proportional element as a control element R further avoids undercutting, ie the rotational speed n_BKM approaches asymptotically to the nominal rotational speed n_setpoint, that is to say without overshooting.

In a further very advantageous embodiment of the invention, a complete order model can be used to determine the estimated torque M_ estimation in the transmission element G ', which is the actual transmission characteristics of the internal combustion engine 10 and possibly the other systems or the motor vehicle describes as accurately as possible.

Furthermore, it is possible to design the transmission behavior of the transmission element G 'not statically but in particular adaptively or self-learning, so that predefinable parameters of the transmission element G' can be adapted as a function of speed control cycles that have taken place. Accordingly, learning algorithms required for this purpose can be used in the control unit 20 ( 3 ) be provided.

Possibly. can in a further embodiment the invention also includes a memory member (not shown), e.g. in shape a PT1 element, for storing the disturbance torque M_stör available be.

In a further very advantageous embodiment of the present invention, instead of the transmission G 'described above, the in 2 shown function structure used to determine the estimated torque M_ estimated, in the manner already described the speed controller 100 out 1 is supplied.

The in 2 shown function structure is a model 200 for the estimation of the disturbance torque M_stör on which the mass moment of inertia J_AS is one with the internal combustion engine 10 coupled powertrain 40 considered, and that is schematically in 4 is shown.

The model according to the invention 200 describes the internal combustion engine 10 and the powertrain 40 as a system of several coupled, rotating elements whose respective rotational moment of inertia is known and whose speed is also known or at least computable. Furthermore, a coupling of the respective systems is taken into account with each other, wherein the coupling can be subject to slip and thus translates the torque acting between the coupled elements accordingly. As an example of a slip coupling is a torque converter 60 called for motor vehicles with automatic transmission.

The car 50 itself or its vehicle mass and the effect of eg a roadway Gradient as a disturbance and a possible slip-related coupling 70 eg by a slipping wheel 70 of the motor vehicle 50 can also in the model of the invention 200 be included, with a wheel speed is used as the corresponding speed, and wherein a corresponding moment of inertia J_KFZ can be determined by measurement or by simulation.

at the moments of inertia J_AS, J_KFZ of the powertrain and the motor vehicle is to be observed that these are dependent on a currently engaged gear.

wobei J_AS, J_KFZ die bereits beschriebenen Trägheitsmomente des Antriebsstrangs und des Kraftfahrzeugs repräsentiert, und wobei J_BKM das Trägheitsmoment der Brennkraftmaschine 10 repräsentiert. Bei

und

handelt es sich um die entsprechenden Winkelbeschleunigungen der jeweiligen Elemente.Overall, one obtains by using the model according to the invention 200 the following equation for estimating the on the internal combustion engine 10 transformed loss moments that arise in the drive train and by external variables such as a road gradient or wheel slip:

wherein J_AS, J_KFZ represents the already described moments of inertia of the drive train and the motor vehicle, and wherein J_BKM the moment of inertia of the internal combustion engine 10 represents. at

and

These are the corresponding angular accelerations of the respective elements.

in the Unlike the ones on the left side of the equation moments of inertia and the angular velocities are the individual moments on the right side of the equation unknown.

The moment M_BKM is a result of the internal combustion engine 10 attacking moment, which results from the combustion and loss moments due to friction and ancillary components, but no coupling with the drive train 40 includes.

The moments M_KM, M_KAS is the coupling moment between the internal combustion engine 10 and a clutch or a torque converter 60 that's the internal combustion engine 10 with the drive train 40 connects, or about the coupling moment between the clutch and the torque converter 60 and the powertrain 40 , The moment M_KKFZ is the coupling moment between the drive train 40 and the motor vehicle 50 or the on the motor vehicle 50 acting disturbances such as the road gradient.

wobei die koppelnden Momente M_KM, M_KAS, M_KKFZ von den jeweiligen Winkelbeschleunigungen

bzw.For the model 200 according to 4 the following differential equation system can be specified:

wherein the coupling moments M_KM, M_KAS, M_KKFZ of the respective angular accelerations

respectively.

sowie ggf. von weiteren bekannten bzw. berechenbaren Größen abhängen. Die Raddrehzahl n_Rad bzw. die entsprechende Winkelbeschleunigung ω_KFZ kann durch das Steuergerät 20 (3) beispielsweise in Form einer Eingangsgröße 20b, bevorzugt jedoch von einem Bremsensteuergerät (nicht gezeigt) erhalten werden, das mit dem Steuergerät 20 über einen ebenfalls nicht abgebildeten Datenbus vernetzt ist.

and possibly depend on other known or calculable sizes. The wheel speed n_Rad or the corresponding angular acceleration ω_KFZ can by the control unit 20 ( 3 ), for example in shape an input variable 20b , but preferably obtained from a brake controller (not shown) connected to the controller 20 is networked via a likewise not shown data bus.

One possibly on a wheel 70 ( 4 ) of the motor vehicle 50 Occurring slip causes in contrast to the torque converter 60 no torque transmission; through the torque translation by means of the torque converter 60 are the torque amounts M_KM on the side of the internal combustion engine 10 but generally from the torque amounts M_KAS on the side of the powertrain 40 different.

The model 200 or an evaluation of the system of differential equations listed above leads to the already mentioned balance equation

The sum of the moments listed on the right side of the equation corresponds to the resulting, on the internal combustion engine 10 attacking loss moment, thus using the model 200 can be determined or estimated from the variables listed on the left side of the equation and thus according to its function according to the estimated torque M_ estimation 1 respectively. 2 equivalent. In particular, for determining the estimated torque M_ estimation by means of the model 200 no knowledge of the moments M_BKM, M_KM, M_KAS, M_KKFZ required, whereby the inventive method is independent of various factors acting on the moments M_BKM, M_KM, M_KAS, M_KKFZ factors such as a changing road grip of the wheel 70 or a temperature dependence of the torque transmission in the torque converter 60 ,

usw. der Bilanzgleichung berücksichtigt und vorliegend ein Antriebsstrang mit einer schlupfenden Einheit, d.h z.B. mit einem oder mehreren schlupfenden Rad 70 (4) betrachtet wird.The already mentioned and in 2 shown function structure is used to implement the model 200 out 4 in the control unit 20 , each branch 210 . 220 a summand

etc. taken into account the balance equation and present a drive train with a slipping unit, ie for example with one or more slipping wheel 70 ( 4 ) is looked at.

wobei vorliegend anstelle der Winkelbeschleunigung

die entsprechende Drehzahl n_BKM verwendet wird, die gem. 2 zunächst dem Differenzierer 31 und anschließend dem Multiplizierer 32 zugeführt wird, um sie mit dem Trägheitsmoment J_AS des Antriebsstrangs 40 (4) zu multiplizieren. Am Ausgang des Multiplizierers 32 wird dementsprechend ein Drehmoment

erhalten, das bei gegebener Drehzahländerung zur Beschleunigung des Antriebsstrangs 40 erforderlich ist.For example, the branch serves 210 to calculate the expression

where present instead of the angular acceleration

the corresponding speed n_BKM is used, the gem. 2 first the differentiator 31 and then the multiplier 32 is supplied to them with the moment of inertia J_AS of the drive train 40 ( 4 ) to multiply. At the output of the multiplier 32 is accordingly a torque

obtained at a given speed change to accelerate the powertrain 40 is required.

A to the acceleration of the motor vehicle 50 required torque is analogous to this and according to the model 200 out 4 at the exit of the in 2 shown multiplier 33 of the branch 220 receive.

As by the dashed arrow 34 in 2 is indicated, further elements or branches can be used to determine the estimation torque M_schätz according to the invention in the same way in order to further increase the accuracy of the method described. As a result, in particular also further elements subject to slip can be taken into account.

The advantage of the determination according to the invention of the estimation torque M_ estimation according to the model 200 compared with the transmission G 'after 1 lies in that with the model 200 It is also possible to take into account soft, ie oscillatable drive trains or drive trains with elements subject to slip in the determination of the estimated torque M_ estim. Vibrations in such drive trains would be in the embodiment according to 1 via the transmission element G 'affect the controlled system and thus affect their leadership behavior.

The referring to 1 described embodiment of the present invention is therefore particularly useful for powertrains with low tendency to oscillate, while the embodiment according to 2 by taking into account different speeds or coupling moments even with oscillating drive trains reliable values for the estimated torque M_ estimated supplies.

Instead of the model 200 The transformation of a vehicle movement or speed into the corresponding rotational speed n_rad and the use of the spin set can be used to model the vehicle 200 Also, the pulse rate are based, with a transformation of the motor vehicle accelerating forces on the internal combustion engine 10 attacking torques is required.

Claims (11)

Method for operating an internal combustion engine ( 10 ), in which a speed (n_BKM) of the internal combustion engine ( 10 ) is controlled as a function of a predefinable setpoint speed (n_setpoint), and in which, depending on a control difference (e) between the speed (n_BKM) and the setpoint speed (n_setpoint) by means of a control element (R), a setpoint torque (M_setpoint) for controlling the internal combustion engine ( 10 ) Is determined, characterized in that a disturbance torque (M_stör), which in particular does not represent measurable disturbance is estimated, and that a (to control the internal combustion engine 10 ) used actuating torque (M_stell) is determined in dependence of the desired torque (M_soll) and the disturbance torque (M_stör). Method according to claim 1, characterized in that in that a proportional element is used as the control element (R). Method according to one of the preceding claims, characterized characterized in that the adjusting torque (M_stell) in dependence is determined by a known loss moment (M_vb), in particular represents measurable and / or calculable disturbances. Method according to one of the preceding claims, characterized characterized in that the disturbance torque (M_stör) and / or adds the known loss moment (M_vb) to the target moment (M_soll) becomes. Method according to one of the preceding claims, characterized in that the disturbance torque (M_stör) as a function of the rotational speed (n_BKM) of the internal combustion engine ( 10 ) and by means of a transmission element (G ') is determined whose transfer function is preferably inverse to a the internal combustion engine ( 10 ) representing the transmission member (G), and the speed (n_BKM) of the internal combustion engine ( 10 ) is transformed into an estimated moment (M_ estimate). Method according to claim 5, characterized in that that the disturbance torque (M_stör) as the difference between the control torque (M_stell) and the estimated torque (M_schätz) is obtained. Method according to one of the preceding claims, characterized in that for the estimation of the disturbance torque (M_stör) a model ( 200 ) is used, which has a moment of inertia (J_AS) of one with the internal combustion engine ( 10 ) coupled powertrain ( 40 ) considered. A method according to claim 7, characterized in that on one of the internal combustion engine ( 10 ) powered vehicle ( 50 ) acting forces in the model ( 200 ), in particular in the form of corresponding mass moment of inertia (J_KFZ). Contraption ( 20 ) for operating an internal combustion engine ( 10 ), with a speed controller ( 100 ) for controlling a rotational speed (n_BKM) of the internal combustion engine ( 10 ) as a function of a predefinable setpoint speed (n_setpoint), and with a control element (R) for determining a setpoint torque (M_setpoint) for controlling the internal combustion engine ( 10 ) in response to a control difference (e) between the rotational speed (n_BKM) and the target rotational speed (n_soll), characterized by a transmission element (G ') for estimating a disturbance torque (M_stör), which in particular represents immeasible disturbance variables. Contraption ( 20 ) according to claim 9, characterized in that the control member (R) is designed as a proportional member. Contraption ( 20 ) according to one of claims 9 or 10, characterized in that the device ( 20 ) is suitable for carrying out the method according to one of claims 1 to 8.