DE19962963A1 - Regulating vehicle engine speed involves predicting revolution rate, detecting predicted, current, desired revolution rates in regulator outputting desired torque to be set by engine controller - Google Patents

Abstract

The method involves determining a desired engine revolution rate with an engine controller depending on a synchronous revolution rate of a ratio to be selected, determining a dynamic characteristic of the torque build-up starting from a current engine speed, a current engine torque and a stored (22) torque history using a predictor (18) that predicts a revolution rate and the predicted, current and desired revolution rates are detected by a regulator (10) that outputs a desired torque to be set by the engine controller (12). Independent claims are also included for the following: an arrangement for regulating a vehicle's engine speed.

Description

The invention relates to a control method a speed of a vehicle engine with engine control tion during a switching operation with the on saying 1 features and a device for Regulation of a speed of a vehicle engine with Engine control during a shift with the features mentioned in claim 10.

State of the art

For vehicles that automatically in their drive train components such as engine, clutch and gearbox, have, is to control the switching process Drive train control provided. This is becoming more common the transmission via a suitable actuator specified a desired translation level, the to be realized via the switching process.

The switching process can be divided into three phases. In a first phase of torque reduction, still existing current translation a moment of  Vehicle engine reduced and the clutch opened. In a subsequent second phase (course change) the current translation level is found taken. In a final phase of moment building the desired translation level is then inserted and the clutch closed again. Existing rotation number differences are usually mechanical compensated by, for example, synchronizer rings in front are seen. Such synchronization leads to high mechanical loads within the Ge drive and is also relatively slow. Furthermore can a speed adjustment only within by the Mechanics certain limits take place, that is, at very high speed differences is a circuit no longer possible without damaging the gearbox.

As a remedy, methods are known in which ei ner the clutch control associated with the clutch Engine speed is changed. Here there is a loading influence of the engine torque specified by the driver tes without speed control in the egg is made in the ordinary sense. About a derar indirect control can limit the The manipulated variables of the motor are insufficient or not at all are not taken into account. So that's an accurate one and fast speed adjustment, which is high Switching comfort would not allow too confusing chen.

Advantages of the invention

About the device according to the invention and the procedure ren to regulate the speed of the vehicle engine with Engine control during the switching process while driving testify with automated transmission with the characteristics of the independent claims can be shown overcome the disadvantages of the prior art. There at means are provided with which a target rotation number of vehicle engine depending on one Synchronous speed of a new translation to be set tion of the transmission is determined. In addition, one Dynamics of the moment building, starting from one current engine speed, a current engine torque and one stored in a moment memory Past moment with the help of a predictor determined, with the predictor one on End of a prediction horizon setting speed is output. Then will the current speed, the predicted speed and the setpoint speed is recorded by a controller whose Output variable to be set via the motor control target torque of the vehicle engine. To this The speed can be adjusted in the sense of an approximation the reference variable target speed can be regulated.

It has proven particularly advantageous in the shown controller route sizes, like a dead time of the internal combustion engine when building torque and a limiter for the engine torque.  

In a preferred embodiment of the invention according to the procedure or the required Device will be a scope to consider past moments can be introduced by introducing a speed-dependent size are taken into account. This speed-dependent size can in turn depend on from the current speed and / or the dead time be determined and as a characteristic of the process for Will be provided. It has also turned out to be proved to be advantageous in predicting the overall number of steps to reach a predicate distribution horizon. The number of steps the one to take into account the moment past should be less than the remaining number of steps, since so that Controller behavior can be influenced positively.

In a further advantageous embodiment of the method according to the invention is the dependence of Setpoint speed from the synchronous speed in such a way ensures that this varies during the switching process can. In the simplest case, the target is speed identical to the synchronous speed, however it is also possible to ramp the target speed or with a different course on the synchron increase speed. It is also conceivable that the target speed around a predeterminable value of the value of the Differences in synchronous speed. That way a particularly robust but also highly flexible turn number adjustment is made.  

He further preferred embodiments of the invention give up 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 schematic block diagram for re regulation of a speed of a vehicle engine with engine control during a gear shift and

Fig. 2 is a schematic flow diagram for the prediction of a speed.

Description of the embodiment

To drive a vehicle are in the drive train usually using components like a vehicle engine Engine control, a clutch and a gearbox featured see. A is used to coordinate these components Drivetrain control depending on one the respective driving situation of the individual components specifies setpoints via associated actuators. Is a shifting requirement via the drive train control in the known and therefore not closer to here determined in an explanatory manner, so a Schaltvor initiated.  

The shifting process is usually divided into three phases, namely a torque reduction, a gear change and a torque build-up. The aim of the method outlined below is to enable synchronization between an engine speed and a synchronous speed, which is regulated via the engine control, in the phase of the gear change. This speed adjustment takes place in a control circuit by a controller 10 , the output variable of which is a setpoint motor torque md _m setpoint. Fig. 1 shows a schematic basic circuit diagram for such a control.

First, an input variable of the controller 10 , namely a target engine speed n _m, target _{, is} to be determined. Starting from a synchronous _speed n _{sync of} a new gear ratio u, this can be defined. The synchronous speed n _{sync is} a product of the gear ratio u and a transmission output speed n _ga . The target engine speed n _m, target is derived from the speed n _sync by the following calculation rule:

n _{m, should} = f (n _sync ).

In the simplest case, the target engine speed is nm, should be identical to the synchronous speed n _sync , but it is also conceivable to specify a different course over time by selecting the function f accordingly. It is also conceivable to increase the target speed n _m, ram in the form of a ram, until the synchronous speed n _{sync is} reached. It is also conceivable that the target speed n _{m should} differ from the synchro speed n _sync even after the end of the phase of the gear change by a predeterminable value.

In addition to the controller 10, further essential components of the control are the engine control 12 with a torque interface 14 , a computing block engine data 16 with a torque memory 22 and a predictor 18 . The control also includes a limiter 20 .

After determining the reference variable n _{m, it} is to be compared with a predicted rotational speed n _{est determined in a} manner to be explained in more detail below, and is input into the controller 10 . The controller itself can be designed as a P or PD controller and calls up the required quantities with a specified cycle time dT.

The limiter 20 is used to limit an output variable made available by the controller 10 , namely a target motor torque md _m , to a predetermined interval. A size md _{m, min} of the smallest possible engine torque at the current engine speed n _{m can set} a lower limit value and a size md _{m, max} that is as large as that at the current engine speed n _m maximum engine torque can set an upper limit value. These variables md _{m, max} or md _{m, min} can also be influenced depending on the target gear ratio u and the driver's desired torque.

A target output torque md _m, target determined in this way is entered into the engine control 12 on the one hand and is transmitted to the torque memory 22 via the interface 14 on the other hand. With the motor control 12 , the respective target moments md _{m, should be} realized in a known manner.

Before determining the predicted speed n _est , a torque past for the current cycle dT must first be determined with the aid of the torque memory 22 . The k-last torque _requests are stored in an array md _hist in the engine data calculation block 16 . Here, md _hist (1) is the current torque request and md _hist (k) is the torque request by time (k-1) × dT. The value k is speed-dependent and is determined in such a way that only the torque requirements that are taken into account for future engine behavior play a role. The values of k are stored in a characteristic curve and can be determined experimentally, for example. Furthermore, in this way, namely via the relationship k = T _t / dT, a dead time T _{t of} the motor is taken into account for a torque realization. The input variables of the predictor 18 are the current engine speed n _m , the current engine torque md _m and the array md _hist .

A flow chart for determining the predicted speed n _est can be found in FIG. 2. The individual calculation blocks 1 to 6 are executed sequentially:
Initially, the variables md _hist , md _m and n _{m are} input in the calculation block 1 . The coefficients a and b for a digital implementation of a delay element of the first order are determined from a time constant T _{1 of} the motor for the torque build-up and the sampling time dT.

In the following _{calculation block} 2 , a moment md _temp and a moment md _{sum are} initialized. The moment md _{temp is} the moment that can probably be set with optimal ignition, while md _{sum is} the sum of the effective moments during the prediction. The block is then run through 3 k times. In it, the moment md _{sum is} calculated, which corresponds to the time integral of the effective motor torques md _effective from the current point in time to the prediction horizon T _pred . Using a function g, a torque-reducing effect of an ignition angle intervention can be taken into account. After the block 3 k times was run, all vergange nen moment demands md _hist, which play a role in the speed development, wor considered to.

In the subsequent arithmetic block 4 , a total number of steps that the prediction takes is determined from the prediction horizon T _pred . It has proven to be advantageous if this number is greater than k in order to achieve good controller behavior.

In arithmetic block 5 , the prediction is continued according to the same principle as in block 3 . Here is the difference be that now no past Mo ment requirements md _hist have to be considered and is therefore assumed to be zero demand. The prediction takes place in total in k _plus steps, where k _{plus represents} the number of steps that the prediction runs longer than the moment past has to be taken into account. The following applies to the prediction horizon T _pred :

T _pred = (k + k _plus ) .dT.

Accordingly, the prediction continues until the prediction horizon T _{pred is} reached.

To determine the predicted speed n _est , a speed difference is added to the current engine speed n _{m in} the computing block 6 . The speed difference is made up of the _sum of the moments md _sum , the sampling time dT and an inertia Dreh of the motor. For reasons of execution speed, this calculation is only carried out once at the end of the prediction, if possible, instead of at each prediction step and the following applies:

Claims (14)

1. Method for regulating a speed of a vehicle engine with engine control during a switching operation in vehicles with an automated gearbox in the

• a) a target speed (n _m, target) of the vehicle engine is determined as a function of a synchronous speed (n _sync ) of a gear ratio (u) to be newly set;
• b) a dynamic of the torque build-up, starting from a current engine speed (n _m ), an actual engine torque (md _m ) and a torque past (md _hist ) stored in a torque memory ( 22 ) and determined with the aid of a predictor ( 18 ) , the predictor ( 18 ) outputting a rotational speed (n _est ) at the end of a prediction horizon (T _pred ) (prediction) and
• c) the current speed (n _m ), the predicted speed (n _est ) and the target speed (n _m, target) are recorded by a controller, the output variable of which is set via the engine control a target torque (md _m, target) of the driver is engine.

2. The method according to claim 1, characterized in that the target torque (md _m, target) is determined as a function of a dead time (T _t ) of the vehicle engine for a torque structure. 3. The method according to any one of the preceding claims, characterized in that the setpoint torque (md _{m, set} ) is limited by a minimum and a maximum adjustable torque (limit values md _{m, min} and md _{m, max} ) at the current engine speed (n _m ) (Limiter 20 ). 4. The method according to claim 3, characterized in that the limit values (md _{m, min} , md _{m, max} ) are determined depending on a target gear ratio (u) to be set and / or the driver torque required by the driver. 5. The method according to any one of the preceding claims, characterized in that the moment past (md _hist ) flows in such a way that a number (k) for the past moments to be taken into account is determined for each prediction. 6. The method according to claim 5, characterized in that the number (k) is determined as a function of the current speed (n _m ) and / or the dead time (T _t ). 7. The method according to any one of claims 5 or 6, there characterized by that the number (k) experiments tell is determined and saved as a characteristic. 5. The method according to any one of claims 5 to 7, there characterized by that the prediction into a Ge total number of steps until the prediction is reached horizon is divided and the number (k) the steps for taking into account the moments past is smaller than the rest of the number of the steps during the prediction. 9. The method according to any one of the preceding claims, characterized in that the target speed (n _m, target) is increased during the switching process according to a function (f) or ramp-like until the synchronous speed (n _sync ) or a reduced by a predetermined value Synchroh speed (n _sync ) it is sufficient. 10. Device for regulating a speed of a vehicle engine with engine control during a switching operation in vehicles with an automatized transmission, in which means are provided by means of which

• a) a target speed (n _m, target) of the vehicle engine is determined as a function of a synchronous speed (n _sync ) of a gear ratio (u) to be newly set;
• b) a dynamic of the torque build-up, starting from a current engine speed (n _m ), an actual engine torque (md _m ) and a torque past (md _hist ) stored in a torque memory ( 22 ) and determined with the aid of a predictor ( 18 ) , the predictor ( 18 ) outputting a rotational speed (n _est ) at the end of a prediction horizon (T _pred ) (prediction) and
• c) the current speed (n _m ), the predicted speed (n _est ) and the target speed (n _m, target) are recorded by a controller, the output variable of which is set via the engine control a target torque (md _m, target) of the driver is engine.

11. The device according to claim 10, characterized in that the device comprises a limiter ( 20 ), the target torque (md _m, target) by a minimum and a maximum adjustable torque (limit values md _{m, min} and md _{m, max} ) limited at the current engine speed (n _m ). 12. Device according to one of the preceding claims 10 or 11, characterized in that the device comprises an interface ( 14 ) to a computing block for engine data ( 16 ) with the torque memory ( 22 ). 13. Device according to one of the preceding claims 10 to 12, characterized in that the device comprises a torque memory ( 22 ) in which a torque past (md _hist ) is stored, which is included in the determination of the speed (n _est ) flows. 14. Device according to one of the preceding claims 10 to 13, characterized in that the device comprises means with which the set speed (n _{m, set} ) is increased during the switching process according to a function (f) or in ramp form until the synchronous speed (n _sync ) or a synchronous speed reduced by a predetermined value (n _sync ) is reached.