DE10026332A1 - Motor vehicle engine to clutch linkage method for gear changes involves fixing value of clutch torque and engine output to provide a control signal with respect to pre-set values - Google Patents

Abstract

The motor vehicle engine to clutch linkage method for gear changes involves fixing the recorded value of the clutch torque as a function of the output torque of the clutch. It involves establishing the recorded value of the motor output (mdmcons) and forming a control and regulation value (mdm,s). The regulating value (mdm,r) is a result of the deviation of the engine regime with respect to a reference value at a given time. The control value results from the path of the engine regime at the same instant (t), of a future trace of the path of the torque with regard to a set curve of the control values of the engine.

Description

The invention relates to a method for coordinating Control of a vehicle engine and a clutch by means of a powertrain control during a Alternating a gear ratio with the one in the upper Concept of claim 1 mentioned features.

State of the art

Modern motor vehicles have drive units, where an increasing number of units auto are manageable. A performance requirement through a driver therefore requires a coordination controlled control of the individual units, in particular for a comfortable start and fast as well to realize comfortable switching operations. As a car automated units come into question a gearbox, a clutch and a vehicle engine. Especially one coordinated control of the last two components In practice, however, th Trouble. So on the one hand the vehicle engine  a target by means of an engine power control worth for an engine torque and on the other hand the automa a setpoint for a clutch moment. Overall is an exact Control of an engine speed required so with closing the clutch a vehicle acceleration The course runs smoothly and stimulates the drive strand vibrations is prevented. Such an exact te control is by the state of the art Technology not yet possible.

Advantages of the invention

By means of the method according to the invention for coordinated control of the vehicle engine and the clutch with the features of claim 1, the two units can be coordinated in a particularly safe and precise manner. By doing

• a) the setpoint for the clutch torque to one Time t as a function of a reference clutch output torque (torque trajectory) fixed is laid and
• b) the setpoint for the engine torque at time t from a regulatory component and a control system share exists, whereby the regulatory share from a deviation of an engine speed of a reference engine speed (speed trajectory) in time and the control share in Dependence on the speed trajectory in time point t, a future course of the speed trajectory  and the moment trajectory and one previous course of the manipulated variables of the driving machine is set (predictive engine control),

can on the specification of standard conditions for a optimal coupling process can be dispensed with and instead, the setpoints are adjusted immediately with reference to the recorded operating parameters operating conditions.

The speed trajectory can preferably be over a Map depending on a driver request, a driver type, a difference in gear ratio and after the change, a driving situation, one Target drive power after the end of the change and one Difference of an engine speed or a gearbox gear speed at the beginning of the change and a re reference period can be set. It turned out to be proven particularly advantageous, first this Re Reference period from a map with the input variables Driver request, driver type, difference in translations, Read driving situation and target drive power.

Furthermore, it has proven to be advantageous that Coupling torque at time t from a control share and a control share. The regulatory part can be derived from a Deviation of the moment trajectory from an estimate determine the clutch output torque at time t, while the control share depending on the Moment trajectory is set.  

In a further advantageous embodiment of the The momentary trajectory is given in this way ben that at the end of changing the gear ratio the desired drive power is achieved. The The moment trajectory is advantageously determined taking into account a driving resistance the one that is on the drive after uncoupling moment.

Furthermore, it has proven to be advantageous to pre dictative engine control a reference transmission speed as well as a dead time behavior for a torque request change. In this way, the Prediction of the engine speed particularly precisely be performed.

In addition, it is advantageous to be predictive Motor control the moment trajectory in a future time interval (prediction horizon) view, with a clutch output torque to Time t approximately the moment trajectory follows. With the help of the dead time behavior and the mo ment trajectory in the prediction horizon can be used Behavior of the vehicle engine depending on a moment of inertia and an angular velocity predict the vehicle engine.

Overall, the measures described can a predictive during predictive engine control graced engine speed at the end of the prediction horizon be calculated. With the help of the predicted The engine speed will then be a corrected course of the  Speed trajectory calculated. Ultimately you can from this corrected curve, manipulated variables for the Torque of the vehicle engine can be determined. By the procedure shown can be the closing of the Clutch and vehicle acceleration especially be carried out comfortably and quickly.

Further advantageous embodiments of the invention result from the rest, in the subclaims mentioned features.

drawings

The invention is in one embodiment example with reference to the accompanying drawings purifies. Show it:

Fig. 1 is a flowchart for determining the target sizes for an engine torque and a clutch torque and

Fig. 2 shows a course of a speed of a driving tool engine or a transmission input shaft during a change of a gear ratio.

Description of the embodiment

In a drive train with automated units, such as a vehicle engine and a clutch, or even an automatic transmission, it is necessary to control the units in a coordinated manner when changing a transmission ratio. For this purpose, it is usually provided to assign a drive train control to the units, which records and evaluates the operating parameters and operating states of the individual units, and provides appropriate manipulated variables for the actuating means assigned to the units. The object of the present method is _to coordinate a setting of a setpoint for an engine torque md _m, target or a clutch torque md _k, target (torque _build-up ).

Fig. 1 shows schematically a flow chart for determining the set values md _{m, intended} for a vehicle engine 10 and md _{k, to} a coupling 12. The respective setpoints are then specified at a time t via suitable actuating means to the motor 10 or the clutch 12 .

The clutch torque md _{k, soll} is determined as a function of a reference clutch output torque md _{ka, ref} (torque trajectory). According to the exemplary embodiment, the clutch torque md _{k, should be} composed of a control component md _{k, r} and a control component md _{k, s} . The control component md _{k, r} is an output variable of a controller 16 , the input variable of which is a controller deviation from the torque trajectory md _{ka, ref} and a clutch output torque md _{ka, est} estimated by an observer 18 . The control portion md _{k, s} is determined via a computing block (clutch control 20 ).

The output of the moment md _{ka, est} estimated by the observer 18 can be carried out as follows:

During a change in the gear ratio, a tensile force is interrupted so that there is no torque on a gearbox output shaft. If there is no braking, an almost constant longitudinal vehicle acceleration a _{l occurs} . With the help of the longitudinal acceleration a _l, a driving resistance can be determined.

First of all, the variable a _{l is} determined by averaging the values for the longitudinal acceleration of the vehicle during the interruption of tractive force (torque transmission to the transmission output shaft μ _g = 0). The longitudinal vehicle acceleration can be determined from a measurement signal from an acceleration sensor or else from a time derivative of a transmission output speed n _ga . The estimated driving resistance f _{fw, est} is given by

f _{fw, est} = -a _{l, too} . (m _fzg + c. Θ),

where vehicle is a vehicle mass and masse is a value for a rotoric moment of inertia of the wheels and shafts up to the gearbox output and the rotating masses of the Gearbox at the gearbox output.

The variable f _{fw, est} determined during the _{interruption of} the tractive force is recorded during engagement and is used to estimate the moment md _{ka, est} . First, during the phase of the torque build-up, an estimated tensile force f _{tens, est} according to the calculation rule

f _{train, est} = f _{fw, est} + a _l . (m _vehicle + c. Θ)

certainly. The estimated clutch output torque md _{k, est is then determined} using the calculation rule

Here, r _{dyn is} a dynamic wheel radius and µ _{diff is} the torque gain of the differential gear and µg the torque gain of the gearbox.

The torque trajectory md _{ka, ref} is specified in such a way that at the end of the gear change at a time t _targ a drive power pw is _{to be} achieved.

In the upper part of FIG. 1, a sequence for determining the target value md _{m, intended} for the motor 10 is shown schematically. Again, the setpoint is composed of a control part md _{m, r} and a control part md _{m, s} . The control part md _{m, r} is determined from a control deviation of a speed n _{m, ref} (speed trajectory) from an engine speed n _m in a controller 24 . By means of a predictive engine control 26 , the control component md _{m, s} can be determined in a manner to be explained in more detail.

The speed trajectory n _{m, ref} can be a function of a driver request, a driver type, a difference s _{id of} the translation before and after the change, a driving situation, the target drive power pw _{, should} after the end of the change and a difference n _{δ , ini} Engine speed n _{m, ini} and a gearbox input speed n _{ge, ini} at the start of the change. First of all, a reference duration t _{ek, ref can be} read out from a characteristic map with the input variables driver request, driver type, difference s _id , driving situation and target drive power pw.

The speed trajectory n _{m, ref} , a future course of the speed trajectory n _{m, ref} and the moment trajectory md _{ka, ref,} as well as a control history of the vehicle engine 10, flow into the predictive engine control 26 as input variables. In addition, a reference transmission input speed n _{ge, ref can also be} taken into account. This is obtained by multiplying the current transmission output speed n _ga by a speed ratio u _{targ of} a desired gear ratio:

n _{ge, ref} = n _ga . u _targ .

To illustrate the following procedure when determining the predictive engine control 26 , FIG. 2 shows a profile of the speed of the transmission input shaft, the vehicle engine 10 and the speed trajectory n _{m, ref} . At the beginning of the change at a time t ₀ , the transmission input shaft and the vehicle engine 10 have very different speeds (points 1 and 5 ), which should have adjusted to one another at the time t _targ (point 6 ). Starting from point 1 , the speed trajectory n _{m, ref is} determined and specified as already explained, while the actual speed n _m can be measured, for example, using a speed sensor. At a time t there is therefore a difference between the setpoint value of the speed and the actual value thereof (points 2 and 3 ). The adjustment of the actual value of the speed n _m to the speed trajectory n _{m, ref} takes place, inter alia, in such a way that a future position of the speed n _m must be determined after a time interval T _pred . This is an essential part of the predictive engine control 26 .

It has proven to be advantageous for the predictive engine control 26 to also incorporate a dead time behavior between the torque request and the torque realization. The following applies:

md _m (t) = md _{m, should} (t - T _t ),

where T _{t is} the effective dead time of the motor 10 when generating the torque. Furthermore, a future course of the moment trajectory md _{ka, ref flows} in in the time interval T _pred . Approximately can thereby be assumed that a clutch output torque md _ka (t) at time t of the Momenttrajektorie _{ka md, ref} follows.

A behavior of the vehicle engine 10 in the time interval T _pred according to the calculation rule can be determined by means of the above-mentioned variables

Θ _m . ωdot _m (t) = md _{m, should} (t - T _t ) - md _ka (t)

determine, where Θ _{m is} a moment of inertia and ωdot _m (t) is an angular velocity of the vehicle engine 10 at time t. This can then be a prediction of the angular velocity ω _{m of} the motor 10 at the time t + T _pred on the context

determine by means of discrete integration. The result of the latter prediction step is a predicted engine speed n _{m, p} at time t + T _pred . Based on the predicted engine speed n _{m, p} , a corrected course of the speed trajectory n _{m, ref is determined} from the time t + T _pred to the time t _targ . For this purpose, the same calculation rules can be used as for the determination of the trajectory n _{m, ref} valid until then. The new trajectory m _{m, ref determined in this way} has a gradient ωdot _{m, ps} for the angular velocity at the start at the time t + T _pred , with the aid of which it then uses a calculation rule

md _{m, s} = Θ _m . ωdot _{m, ps} + md _{ka, ref} (t + T _pred )

a manipulated variable md _{m, s is determined} for the actuating means of the vehicle engine 10 .

Claims (13)

1. Method for coordinated control of a vehicle engine and a clutch by means of a drive train control during a change of a transmission, wherein the vehicle engine and the clutch development are each assigned at least one adjusting means with which a setting of a setpoint for an engine torque or a coupling torque occurs (torque build-up), characterized in that

• a) the setpoint for the clutch torque (md _{k, soll} ) is determined at a point in time (t) as a function of a reference clutch output torque (md _{ka, ref} ) (torque trajectory) and
• b) the setpoint for the engine torque (md _{m, soll} ) at the time (t) consists of a control component (md _{m, r} ) and a control component (md _{m, s} ), where the control component (md _{m, r} ) consists of a deviation of an engine speed (n _m ) from a reference engine speed (n _{m , ref} ) (speed trajectory) at the time (t) and the control component (md _{m, s} ) depending on the speed trajectory (n _{m, ref} ) at the time (t), a future course of the speed trajectory (n _{m, ref} ) and the moment trajectory (md _{ka, ref} ) as well as a previous course of the manipulated variables of the vehicle engine is determined (predictive engine control).

2. The method according to claim 1, characterized in that the speed trajectory (n _{m, ref} ) as a function of a driver request, a driver type, a difference (s _id ) of the translations before and after the change sel, a driving situation, a target Drive power (pw _{on, should} ) after the end of the change and a difference (n _{δ , ini} ), an engine speed (n _{m, ini} ) and a transmission input speed (n _{ge, ini} ) at the start of the change. 3. The method according to any one of the preceding claims, characterized in that the clutch torque (md _{k, should} ) at the time (t) from a control part (md _{k, r} ) and a control part (md _{k, s} ) be, where the control component (md _{k, r} ) results from a deviation of the torque trajectory (md _{ka, ref} ) from an estimated clutch output torque (md _{ka, est} ) at the time (t) and the control component (md _{k, s} ) depending on the torque trajectory ( md _{ka, ref} ) is determined. 4. The method according to claim 3, characterized in that the estimated clutch output torque (md _{ka, est} ) is determined as a function of a driving resistance. 5. The method according to claim 4, characterized in that to determine the estimated clutch output moment (md _{ka, est} ) during the phase of the tractive force interruption

• - First an estimated driving resistance (f _{fw, est} ) according to the calculation rule
  f _{fw, est} = a _{l, too} . (m _fzg + c. Θ),
  is determined, where (m _fzg ) a vehicle mass, (a _{l, zu} ) a vehicle longitudinal acceleration, averaged during the phase of the tractive force interruption, and (Θ) a value for a rotor moment of inertia of the wheels and shafts to the transmission output and the rotating Masses of the gearbox at the gearbox output,
• - During the torque build-up phase, an estimated tensile force (f tensile _{, est} ) according to the calculation rule
  f _{train, est} = f _{fw, est} + a _l . (m _vehicle + c. Θ)
  is determined and
• - then the estimated clutch output torque (md _{k, est} ) from the context
  can be calculated, where (r _dyn ) is a dynamic wheel radius and (µ _diff ) the torque gain of the differential gear and (µg) the torque gain of the gearbox.

6. The method according to any one of the preceding claims, characterized in that the moment trajectory (md _{ka, ref} ) is specified such that at the end of the change in a time (t _targ ) the drive power (pw _{on, should} ) is reached. 7. The method according to one or more of the preceding claims, characterized in that for the predictive engine control a reference gearbox input speed (n _{ge, ref} ) according to the calculation rule
n _{ge, ref} = n _ga . u _targ
is determined, where (n _ga ) is a current transmission output speed and (u _targ ) a gear ratio of the transmission after the change. 8. The method according to one or more of the preceding claims, characterized in that for predictive engine control a dead time behavior is taken into account when requesting a torque and applies to the moment (md _m (t)) transmitted at the time (t):
md _m (t) = md _{m, should} (t - T _t ),
where (T _t ) is a dead time of the vehicle engine. 9. The method according to one or more of the preceding claims, characterized in that for the predictive engine control the moment trajectory (md _{ka, ref} ) is taken into account in a time interval (T _pred ) (prediction horizon), with a clutch output torque (md _ka (t )) approximately follows the moment trajectory (md _{ka, ref} ) at time (t). 10. The method according to claims 8 and 9, characterized in that for predictive engine control a behavior of the vehicle engine in the time interval (T _pred ) according to the calculation rule
Θ _m . ωdot _m (t) = md _{m, should} (t - T _t ) - md _ka (t)
is determined, where (Θ _m ) is a moment of inertia and (ωdot _m (t)) is a time derivative of the angular velocity of the vehicle engine at time (t). 11. The method according to claim 10, characterized in that an angular velocity (ω _m (t + T _pred )) at the time (t + T _pred ) according to the calculation rule
given is. 12. The method according to one or a combination of claims 5 to 11, characterized in that the predictive engine control delivers a predicted engine speed (n _{m, p} ) at the time (t + T _pred ) and with the engine speed (n _{m, p} ) corrected course of the speed trajectory (n _{m, ref} ) from the time (t + T _pred ) to the time (t _targ ) is determined, the speed trajectory (n _{m, ref} ) thus determined at the time (t + T _pred ) having a gradient (ωdot _{m, ps} ). 13. The method according to claim 12, characterized in that a manipulated variable (md _{m, s} ) for the torque of the vehicle engine according to the calculation rule
md _{m, s} = Θ _m . ωdot _{m, ps} + md _{ka, ref} (t + T _pred )
is determined.