DE102005032007A1 - Method for controlling of controllable torque transmission unit of especially motor vehicle engines in drive trains entails determining target torque as function of at least actual torque of engine - Google Patents

Abstract

The method for the controlling of a controllable torque transmission unit of especially motor vehicle engines in drive trains entails establishing a starting nominal RPM of the internal combustion engine to be maintained, establishing the actual torque of the engine during starting, and establishing the target torque of the torque transmission unit, whereby the target torque is determined as a function of at least the actual torque of the engine. The starting nominal RPM to be maintained is determined from an engine characteristic depending upon the accelerator angle, and the target torque is additionally a function of the actual engine RPM to the nominal engine RPM.

Description

The The invention relates to a method for controlling the starting strategy of internal combustion engines, in particular motor vehicle engines, with an automatic transmission with at least one controllable Torque transmission unit preferably a coupling, are connected.

at starting operations Transmission systems with at least one automated torque transmission device Often there is the desire, speed curves of the internal combustion engine pretend. Such speed curves become dependent determined by consumption aspects or comfort aspects.

From the DE 199 25 664 C2 For example, a method is known in which a speed control system adjusts a desired motor speed.

Indeed Often there is the problem that a deviation of the actual engine torque from an engine nominal torque determined from an engine map leads, that the start-up target speed can not be adjusted.

It It is an object of the invention to provide a method for controlling the approach strategy to provide by internal combustion engines, with the help of a Start-up speed of the internal combustion engine explicitly specified and can be respected.

These The object is achieved by a method having the features of the claim 1 solved. Preferred embodiments are in the dependent claims specified.

• – Bestimmen einer einzuhaltenden Anfahr-Soll-Drehzahl der Verbrennungskraftmaschine:
• – Ermitteln des Motor-Ist-Moments während des Anfahrens; und
• – Korrigieren der Anfahrstrategie durch Aufbringen eines Zielmoments durch die Drehmomentenübertragungseinheit, wobei das Zielmoment als Funktion von zumindest dem Motor-Ist-Moment und einem Korrekturfaktor festgelegt ist.

The method for controlling the starting strategy of internal combustion engines, in particular motor vehicle engines, having an automatic transmission with at least one controllable torque transmission unit, contains the steps:

• Determining a start-up target speed of the internal combustion engine to be observed:
• - Determining the actual engine torque during startup; and
• - Correcting the starting strategy by applying a target torque by the torque transmission unit, wherein the target torque is determined as a function of at least the actual engine torque and a correction factor.

kick a deviation of the actual engine torque from one of, for example a map in advance engine torque, this can Deviation due to dependency the torque of the torque transmission unit, i.e. the torque with which the torque transmission unit loads will be corrected by the actual engine torque. The target moment is e.g. a clutch torque. Optionally, the Target torque or the detected engine torque filtered to vibrations to avoid in the scheme. Through the individual adaptation of the Correction factor, the course of the starting torque can be determined.

preferred Way is to be observed start-up target speed from one of Dependent on accelerator pedal angle Motor map determines, where the target moment additionally a function of the ratio from actual engine speed to engine target speed. This has the The advantage of being able to set a target speed that is only required by the driver, represents by the accelerator pedal slope, depends.

To An alternative preferred embodiment is the one to be respected Start-set speed determined from a motor-actual speed-dependent engine map. This makes possible, that the clutch torque primarily from the actual engine speed depends.

Preferably will the procedure for applied the regulation of the starting strategy of a motor vehicle engine, wherein the torque transmitting device a clutch is and the target torque is a clutch target torque.

wobei

TrqCITgt

das Kupplungs-Ziel-Moment,

TrqEngNew

das Motor-Ist-Moment,

nEng

die Motor-Ist-Drehzahl,

nLL

die Motor Leerlaufdrehzahl,

nEng,Soll

die Anfahr-Soll-Drehzahl des Motors und

TupFactor

der Korrekturfaktor ist.

According to a further preferred embodiment, the clutch torque is during the approach calculated according to the formula:

in which

TrqCITgt

the clutch target moment,

TrqEngNew

the actual engine torque,

nEng

the actual engine speed,

nLL

the engine idle speed,

nEng, Soll

the start-up target speed of the engine and

TupFactor

the correction factor is.

The Determination of the clutch target torque according to this formula allows a exact compliance with the starting speed, which are freely chosen can.

Preferably the correction factor is a function of the ratio of actual engine torque to the engine target torque. For example, the factor can be linear with increasing ratio from motor-actual-torque to engine-set-torque increasing, as long as the actual engine speed does not exceed the motor setpoint speed. Thereafter, the slope of the correction factor, in the course between Zero and a ratio of Actual motor torque at the desired engine torque of one is preferably linear also increases between zero and one, so steeper that he stronger rises as the ratio from actual engine torque to engine torque. Thus, overspeeding of the engine ("turning away") are prevented.

To a further advantageous embodiment example may additionally Offset be introduced.

wobei nOff günstigerweise zwischen O und nLL liegen kann.For this applies:

where nOff may favorably be between O and nLL.

A proper choice of this offset causes the moment building earlier and softer starts than without. Due to the earlier construction of the clutch torque the engagement process is made softer and the ride comfort elevated. The danger of an engine speed overshoot can be further reduced.

To a preferred embodiment In addition, an engine acceleration is set for setting the start-up target speed considered. This can be done, for example, that from a motor map a plateau speed of the internal combustion engine is determined and this a speed gradient is added so that the start-up target speed increases the plateau speed through the speed gradient. If the speed gradient is zero, corresponds to the start-set speed of the determined from the engine map platform speed.

Preferably is the speed gradient added to the plateau speed not equal to zero, if between the plateau speed and the Start-up speed the torque characteristic of the motor map, off the plateau speed is determined, has a slope ≥ zero. The characteristic curve is preferably a characteristic curve that is constant Throttle angle or a constant accelerator pedal angle corresponds.

For cases in to which a falling moment line between the plateau speed and the approach-set speed in the engine map is present, instead of the speed gradient equal to zero set, preferably an engine intervention made such that the engine torque remains at least constant. In particular, for example means of so-called e-gas over the Speed increase the throttle will be opened further, so that one above the Speed to achieve constant or increasing engine torque. It This will result in a motor characteristic with a higher throttle angle changed.

In this case, the engine torque is preferably increased by at least the acceleration torque siege.

following the invention will be described by way of example with reference to the accompanying drawings described in which:

1 an accelerator pedal dependent map for determining the Zielanfahrdrehzahl shows;

2 shows the problem of the deviation of an actual engine torque from the engine torque determined from the characteristic map;

3 shows an example of a course of the correction factor;

4 shows a starting process with a start-up control with the strategy according to the invention;

5 is a diagram for explaining a start-target speed curve; and

6 an example of an engine map of a naturally aspirated engine for explaining the increase of the engine speed during the startup process is.

If an essentially freely adjustable starting speed is to be predetermined and maintained for an automatic transmission of a motor vehicle, according to a preferred embodiment of the method according to the invention, initially the starting nominal speed nEng, target is explicitly specified. For this purpose, the start-up speed of the motor is determined, for example, from the characteristic curve which is in 1 is shown. Depending on the accelerator angle that the driver selects, the desired start-up target speed (target approach speed) is determined. For example, corresponds to an accelerator pedal angle from the rest position of 50% of the maximum possible accelerator pedal angle Zielanfahrdrehzahl of almost 1400 U / min (Z1 in 1 ).

By the dependence the start-up target speed from the accelerator pedal angle can only reach the target starting speed dependent be adjusted by the driver's request. Instead of the gas pedal-dependent engine map it is also possible the start-up target speed depends on the actual motor torque do.

When the start-up target speed is determined, a start-up speed deviation from the start-up target speed may occur in a conventional start-up strategy that does not provide correction when the actual engine torque is shown at a certain accelerator pedal angle (FIG in 2 eg 100% accelerator pedal) deviates from the engine set torque. In this case, the starting speed determined by the starting characteristic can not be maintained.

Therefore, a specific target clutch torque TrqCITgt is applied to the clutch as the controllable torque transmission unit of the internal combustion engine. The target clutch torque depends on the one hand on the instantaneous engine torque, ie the actual engine torque TrqEngNew, and on the other hand on a ratio between the actual engine speed nEng and the engine target speed nEng, Soll. The additionally used correction factor TupFactor serves to specify any gradients of the starting torque and to adapt them individually. For example, the clutch torque transmitted by the clutch during startup is determined according to the following formula:

In order to can by controlling the clutch torque, the predetermined start-target speed be adhered to and thus the start-up speed set explicitly become.

Certainly one deviating from the illustrated embodiment, the start-target speed neng, Soll dependent on From the actual engine torque TrqEngNew, so this has the advantage that the Clutch torque in first approximation depends on the actual engine speed, there denominator and counter the equation to the same degree change. However, in this case, no direct connection between Accelerator pedal angle and start-up target speed, often by the driver required is to be respected.

Instead of directly introducing the actual engine torque unfiltered into the equation above, it is possible not to transmit vibrations in the engine torque to the clutch target torque or the Re destabilize vibration, to filter the engine torque. In this case, conventional mathematical filtering methods come into consideration.

An example of the course of the correction factor TupFactor, which depends on the ratio of the actual motor speed to the motor set speed, is in 3 specified.

If one applies the corresponding clutch torque to the clutch of a motor vehicle, then, in the case of a correction factor curve, which in the uppermost part of FIG 4 is shown, the start-up target speed of the engine is reached quickly and kept constant, as from the bottom diagram of 4 can be seen. In 4 the abscissa indicates the time taken during the start-up procedure.

Should additionally for explicitly specifying the start-up target speed and its setting also maintained a certain speed curve during startup are, it is preferred that in the start-target speed additionally on Speed gradient is received.

One Such with the help of a speed gradient optimized course of Starting speed can provide a compromise, on the one hand before When grinding, the speed remains on a speed plateau should, so no energy for the acceleration of the motor mass is necessary and the total energy can be used to accelerate the drive train and On the other hand, a speed plateau should be avoided for what acoustic reasons speak. Furthermore the avoidance of a speed plateau serves to minimize the Frictional energy. Preference is therefore from a first starting speed (Intermediate speed) given a speed gradient until a synchronous speed is reached, so while the approach a continuous increase in engine speed takes place.

Assuming that an existing engine torque on the one hand can be used to accelerate the engine and / or can be forwarded to the clutch; MMot = J * ω + MKupp, the actual setpoint speed during the startup procedure results from the formula:

wobei nlnpShaft die Beschleunigung der Getriebeeingangswelle ist, die gemessen oder berechnet werden kann.The start-up target speed determined, for example, according to one of the previously described methods is defined as the platform speed nEngPlateau, to which a speed gradient is added. The speed gradient is determined, for example, by determining the time duration until the engine speed and transmission input speed are synchronous. This time is determined as follows:

where nlnpShaft is the acceleration of the transmission input shaft that can be measured or calculated.

A speed curve over time is in 5 where nGet is the gearbox speed and nMot is the engine speed. The synchronous speed, ie same transmission and engine speed, is reached at the speed g at time c. The predetermined by the approach strategy described above Start-up speed corresponds to the speed e. The normal speed curve with plateau speed of the motor is shown by solid lines, while the corrected speed curve corresponds to the dashed line. In 5 is shown a linear target speed curve between the plateau speed and the synchronous speed. In principle, however, any other mathematically describable courses or courses which can be filed by characteristic curves are also possible.

By this calculation of the start-up target speed including the Difference between synchronous speed and plateau speed can be Speed plateau to be prevented in the starting process. Becomes a plateau desired so the start-up target speed as previously described with the Plateau setpoint speed equated, i. the speed gradient (second Part of the equation) is set to zero.

vor, wird die Korrektur der Anfahrkennlinie vorzugsweise unter Berücksichtigung des Motorkennfelds der Antriebsmaschine vorgenommen. Insbesondere gibt es in einem Kennfeld, das beispielhaft in 6 dargestellt ist, Bereiche für nahezu alle Drosselklappenwinkel, in denen das Drehmoment mit steigender Drehzahl fällt (siehe beispielsweise 6, 10% Drosselklappe: der gesamte Bereich). Das bedeutet, dass ein Drehzahlanstieg bei konstanter Drosselklappe eine Verringerung des Motormoments bedeutet, was nicht sinnvoll ist. Andererseits gibt es Bereiche, in denen eine Erhöhung der Drehzahl während des Anfahrvorgangs sinnvoll ist, da in diesen Bereichen der Drehzahlanstieg mit einem Anwachsen des Motormoments verbunden ist.But if you give a speed gradient

Before, the correction of the starting characteristic is preferably made taking into account the engine map of the engine. In particular, there is a map that exemplifies in 6 shown ranges for almost all throttle angle, in which the torque falls with increasing speed (see, for example 6 , 10% throttle: the entire range). This means that a constant throttle speed increase means a reduction in engine torque, which does not make sense. On the other hand, there are areas in which an increase in the speed during the start-up process makes sense, since in these areas the speed increase is associated with an increase in the engine torque.

Would like to be in the in 6 Starting at the engine speed of 1250 rpm at 10% Throttle Valve (P1), you can see from the engine map that the associated torque curve is above the speed at constant throttle valve angle. Increasing the speed from P1 to P2 at the same throttle valve angle, so it goes with a torque reduction of about 130 Nm to 110 Nm accompanied. At a throttle angle of 20%, the situation is different at the corresponding point P3 at a speed of 1250 rpm, since here the engine torque is increasing. In this case, in this case, the increase in the speed from the target speed-plateau point at 1200 rpm to about 1500 rpm makes sense, since an increase in engine torque is associated with it.

Whether the approach strategy is corrected by increasing the plateau speed by a speed gradient is preferably decided depending on whether in the engine map so that an engine torque increase is connected. If this is not the case, the speed gradient is optionally set to zero or it is simultaneously made a throttle valve increase. For the point P1 in the engine map according to 6 this means that the approach strategy determines that the speed increase around the speed gradient would be associated with a drop in engine torque (to P2). Therefore, in a first step, the speed gradient is set to zero, whereby at least a plateau is achieved and the engine torque is kept constant. Preferably, however, the speed gradient is taken into account in a second step, which leads to a speed increase (arrow in FIG 6 , from 1250 rpm to 1750 rpm), wherein at the same time the throttle valve is opened further, so that is changed from a specific throttle valve angle associated characteristic to another characteristic. For the in 6 The strategy shown in this example means that starting from P1 at a speed of 1250 rpm and a throttle opening of 10%, the speed is increased to 1750 rpm and at the same time the throttle opening is increased to 15%. Thus, the speed increases between P ₁ and P ₄ , wherein the engine torque also increases slightly or at least remains the same.

Claims (12)

Method for controlling a controllable torque transmission unit of drive units contained in the drive train, in particular Motor vehicle engines, with an automatic transmission, the procedure containing the steps: (a) Establish a to be respected Start-up speed of the internal combustion engine; (b) During the Start-up: determining the actual engine torque of the prime mover; and (c) creating the target torque of the torque transmitting unit, where the target moment is a function of at least the actual engine torque is fixed. A method according to claim 1, characterized in that the start-up target speed to be observed is determined from a dependent of the accelerator pedal engine characteristic and the target torque additional function of the ratio of actual engine speed to engine target speed. Method according to claim 1, characterized in that that the start-up target speed to be maintained from one of the engine-actual speed dependent Motor characteristic is determined. Method according to one of the preceding claims, characterized in that the torque transmission device is a Clutch is and the target moment is a clutch-target moment. A method according to claim 4, characterized in that the clutch torque is calculated during the approach according to the following formula:

where TrqCITgt is the clutch target torque, TrqEngNew is the actual engine torque, nEng is the engine's actual speed, nLL is the engine idle speed, nEng, is the startup target speed of the engine, and TupFactor is the correction factor. Method according to claim 5, characterized in that the correction factor is a function of the ratio of actual motor speed to motor setpoint speed (nEng / nEng, setpoint). The method of claim 6, wherein the value of the correction factor with increasing value of the ratio the instantaneous speed of the engine to the target speed increases and the increase stronger will, as soon as the ratio is equal to 1. Method according to one of the preceding claims, characterized in that for setting the start-up target speed additionally a Engine acceleration considered becomes. Method according to claim 8, characterized in that that the start-up target speed by a determined from a motor map plateau speed of Internal combustion engine and a speed gradient determined is, wherein the start-up target speed increases the plateau speed the speed gradient is. Method according to claim 9, characterized in that that the speed gradient is not equal to zero, if between the plateau speed and the approaching setpoint speed the torque characteristic the engine map, in particular a characteristic which is a constant Throttle angle corresponds, has a slope ≥ 0. Method according to claim 9, characterized in that that for a falling between plateau speed and start-up target speed Torque characteristic of the engine map, in particular a characteristic, which corresponds to a constant throttle angle, an engine intervention is made such that the engine torque at least constant remains. Method according to claim 11, characterized in that that the engine torque is increased at least by the acceleration torque becomes.