DE19962963B4 - Method and device for controlling a speed of a vehicle engine with motor control during a switching operation - Google Patents

Abstract

A method for controlling a speed of a vehicle engine with engine control during a switching operation in vehicles with an automated transmission in the
(a) a target speed (n _{m, soll} ) of the vehicle engine is determined in dependence on a synchronous speed (n _sync ) of a newly set ratio (u) of the transmission;
(b) a dynamics of the torque build-up, based on a current engine speed (n _m ), a current engine torque (md _m ) and a stored torque in a memory (22) torque history (md _hist ) and using a predictor (18) is determined wherein by the predictor (18) a presumed at the end of a prediction horizon (T _pred ) speed (n _est ) is output (prediction) and
(C) the current speed (n _m ), the predicted speed (n _est ) and the target speed (n _{m, soll} ) are detected by a controller, the output of which an over the engine control einzustellendes set torque (md _{m, soll} ) of the vehicle engine is.

Description

The The invention relates to a method for controlling a rotational speed of a Vehicle engine with engine control during a shift with the features mentioned in claim 1 and a device for Control of a speed of a vehicle engine with engine control while a switching operation with the features mentioned in claim 10.

State of the art

From the DE 43 27 906 A1 For example, a device for reducing the engine torque between the beginning and the end of a shifting operation of the transmission in motor vehicles is known. In this case, a control unit is provided that detects the beginning of a shift operation and continuously the current engine speed and that calculates the expected at the end of the shift operation engine speed. The amount of reduction of the engine torque between the start and the end of the shift is controlled so as to achieve a predetermined engine speed history.

at Vehicles that have automated components in their powertrain, as engine, clutch and gearbox, is to control the switching process provided a drive train control. This is usually done via a suitable actuator specified the transmission a desired gear ratio, the above the switching process should be realized.

Of the Switching operation leaves divided into three phases. In a first phase of the torque reduction becomes a moment of the vehicle engine if the current translation still exists reduced and the clutch opened. In a subsequent second Phase (gear change), the current gear ratio is taken out. In a final phase of torque building then the desired translation stage inserted and the clutch closed again. Existing speed differences are usually mechanically compensated by, for example Synchronizer rings are provided. Such synchronization leads to high mechanical loads within the transmission and is also relative slowly. Furthermore, a speed adjustment only within determined by mechanics limits, that is, at very high speed differences, a circuit is no longer without damage of the transmission possible.

to Remedy methods are known in which by one of the clutch associated clutch control, the engine speed is changed. in this connection an influencing of the engine torque given by the driver, However, without a speed control made in the true sense becomes. about Such indirect control can be limitations of the manipulated variables of the Motors are considered inadequate or not at all. This is an accurate and fast speed adjustment, which gives a high shifting comfort enable would, not to be realized.

Advantages of the invention

About the inventive device and the method for controlling the speed of the vehicle engine with Motor control during the switching process on vehicles with automated gearbox with the characteristics of the independent claims can be overcome the disadvantages of the prior art. In this case, means are provided with which a setpoint speed of the vehicle engine dependent on from a synchronous speed of a newly set translation of the transmission is determined. In addition, a momentum of momentum building, starting from a current engine speed, a current engine torque and a past in a torque memory past moments with the help of a predictor determined by the predictor one at the end of a prediction horizon expected setting speed is output. Subsequently, the current speed, which predicted Speed and the setpoint speed detected by a controller, the output of which via the Motor control to be set target torque of the vehicle engine is. In this way, the speed in the sense of an approximation the reference variable setpoint speed be managed.

It has proved to be particularly advantageous in the indicated Regulator route sizes, such as a dead time of the internal combustion engine during torque build-up and a Limiter for the engine torque to record.

In a preferred embodiment of the method according to the invention or of the required device, a scope of the past moments to be considered can be taken into account by introducing a speed-dependent variable. This speed-dependent variable can in turn be determined as a function of the current speed and / or the dead time and be provided as a characteristic of the method. It has also proved to be advantageous to divide the prediction into a total number of steps until a prediction horizon is reached. The number of steps that are taken into account to account for the moment past should, if possible, smaller than the remaining number of Be steps, as this way the controller behavior can be positively influenced.

In a further advantageous embodiment of the method according to the invention becomes the dependency the target speed of the synchronous speed designed such that this while of the switching operation can vary. Although in the simplest case the target speed is identical to the synchronous speed, however it also possible the setpoint speed ramp-shaped or else to increase the synchronous speed with another course. Conceivable is also that the setpoint speed by a predetermined value from Value of the synchronous speed differs. This way a can particularly robust but also highly flexible speed adaptation.

Further preferred embodiments of the invention will become apparent from the others, in the subclaims mentioned features.

drawings

The Invention will be described below in an embodiment with reference to the accompanying drawings explained in more detail. It demonstrate:

1 a schematic block diagram for controlling a speed of a vehicle engine with engine control during a switching operation and

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

Description of the embodiment

To the Driving a vehicle are usually components in the powertrain like a vehicle engine with engine control, a clutch and a Gear provided. To coordinate these components is a Driveline control, depending on from a particular driving situation the individual components over coordinated Actuators presets setpoints. Will over the driveline control a Schaltnotwendigkeit in known and therefore not closer here to be explained Determined way, so a switching operation is initiated.

The shift 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 allow in the phase of the gear change controlled via the engine control synchronization between an engine speed and a synchronous speed. This speed adjustment takes place in a control loop by a controller 10 , whose output is a target engine torque md _{m, should} . The 1 shows a schematic block diagram for such a scheme.

First is an input of the regulator 10 , Namely, a target engine speed n _{m, soll} , to determine. Based on a synchronous _speed n _sync a new translation stage u, this can be set. Here, the synchronous speed n _{sync is} a product of the translation stage u and a transmission output speed n _ga . The target engine speed n _{m, shall be} derived from the speed n _sync by the following calculation rule: n m, to = f (n sync )

In the simplest case, the target engine speed n _{m, should be} identical to the synchronous speed n _sync , However, it is also conceivable to specify by appropriate choice of the function f a different course over time. It is also conceivable, the target speed n _{m, is} to increase ramped until the synchronous speed n _{sync is} reached. It is also conceivable that the setpoint speed n _m, even after the end of the phase of change gear still differs by a predetermined value of the synchronous speed n _sync .

Other essential components of the control are in addition to the controller 10 the engine control 12 with a moment interface 14 , a computing block engine data 16 with a moment store 22 and a predictor 18 , Furthermore, the regulation includes a limiter 20 ,

After determining the reference variable n _m, this is compared with a predicted speed n _est determined in a manner to be explained in more detail below and is input to the controller 10 , The controller itself can be designed as a P or PD controller and calls the required quantities with a given cycle time dT.

The limiter 20 serves for; one from the regulator 10 provided output variable, namely a target engine torque md _{m, is} to limit to a predetermined interval. Thus, a variable md _{m, min of} a minimum possible engine torque at current engine speed n _m a lower limit and a size md _{m, max} , which is as large as the current engine speed n _m maximum engine torque, set an upper limit. These variables md _{m, max} or md _{m, min} can be influenced in addition depending on the target ratio u and the driver's desired torque.

Such a predetermined output torque md _{m, should} be on the one hand input to the engine control 12 and on the other hand, via the interface 14 to the moment store 22 transmitted. With the engine control 12 can be in a known manner, the respective desired moments md _{m, should} realize.

Before determining the predicted speed n _est must first with the help of the torque memory 22 a moment past for the current cycle dT be determined. In the calculation block motor data 16 the k-last moment _requests are stored in an array md _hist . Here, md _hist (l) is the current moment demand and md _hist (k) is the torque demand past the time (k-1) × dT. The value k is speed-dependent and so determined that only the torque requirements play a role, which are taken into account for future engine behavior. The values of k are stored in a characteristic curve and can be determined experimentally, for example. Furthermore, in this way, namely on the relationship k = T _t / dT, a dead time T _{t of} the engine for torque realization is taken into account. 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 is the 2 refer to. In the process, the individual computation blocks become 1 to 6 executed sequentially:
First, find in the computational block 1 the sizes md _hist , md _m and n _m entrance. From a time constant T ₁ of the torque-building motor and the sampling time dT, the coefficients a and b are determined for a digital realization of a first-order delay element.

In the following calculation block 2 a moment md _temp and a moment md _{sum are} initialized. Here, the moment md _{temp is} the moment that is likely to be set at optimal ignition, while md _{sum is} the sum of the effective moments during the prediction. Below is the block 3 go through k times. In it, the moment md _{sum is} calculated, which corresponds to the time integral of the effective engine torques md _effective from the current time to the prediction _horizon T _pred . By a function g, a torque-reducing effect of a Zündwinkeleingriffs can be considered. After the block 3 has been traversed k times, all past moment requests md _hist , which play a role for the speed development, have been taken into account.

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

In the arithmetic block 5 the prediction follows the same principle as in the block 3 continued. Here, the difference is that now no past moment demands md _{hist are} to be considered and therefore zero is assumed as a claim. The total prediction is in k _plus steps, where k _{plus represents} the number of steps that the prediction takes longer than the moment past has to be considered. For the prediction horizon T _pred , the relationship applies: T pred = (k + k plus ) · DT.

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

To determine the predicted speed n _est is in the arithmetic block 6 to the current engine speed n _m adds a speed difference. The speed difference is composed of the momentum _sum md _sum , the sampling time dT and a rotational inertia Θ of the motor. For reasons of speed of execution, this calculation is carried out, if possible, only once at the end of the prediction, instead of at every prediction step, and the following applies:

Claims (14)

A method for controlling a speed of a vehicle engine with engine control during a switching operation in vehicles with an automated transmission in which (a) a target speed (n _{m, soll} ) of the vehicle engine in response to a synchronous speed (n _sync ) of a newly set translation (u) of the Transmission is determined; (b) a dynamics of the torque build-up, starting from a current engine speed (n _m ), a current engine torque (md _m ) and one in a torque memory ( 22 ) stored past moments (md _hist ) and with the help of a predictor ( 18 ) is determined by the predictor ( 18 ) a presumed at the end of a prediction horizon (T _pred ) speed (n _est ) is output (prediction) and (c) the current speed (n _m ), the predicted speed (n _est ) and the target speed (n _{m, soll} ) are detected by a controller whose output is a deliverable via the engine control target torque (md _{m, soll} ) of the vehicle engine. A method according to claim 1, characterized in that the desired torque (md _{m, soll} ) is determined as a function of a dead time (T _t ) of the vehicle engine for a torque build-up. Method according to one of the preceding claims, characterized in that the desired torque (md _{m, soll} ) by a minimum and a maximum adjustable torque (limits md _{m, min} and md _{m, max} ) at the current engine speed (n _m ) is limited (limiter 20 ). A method according to claim 3, characterized in that the limit values (md _{m, min} , md _{m, max} ) depending on a set target ratio (u) and / or requested by the driver driver torque are set. Method according to one of the preceding claims, characterized in that the torque history (md _hist ) is incorporated in such a way that for each prediction a number (k) is determined for the past moments to be considered. A method according to claim 5, characterized in that the number (k) depending on the current speed (n _m ) and / or the dead time (T _t ) is set. Method according to one of claims 5 or 6, characterized that the number (k) is determined experimentally and stored as a characteristic becomes. Method according to one of claims 5 to 7, characterized that the prediction into a total number of steps to reach the prediction horizon is divided and the number (k) of the steps for consideration the moment past is smaller than the remaining number of Steps during the prediction. Method according to one of the preceding claims, characterized in that the setpoint speed (n _{m, soll} ) is increased during the switching operation according to a function (f) or in a ramp until the synchronous speed (n _sync ) or a synchronous speed (n _sync ) is achieved. Device for controlling a rotational speed of a vehicle engine with engine control during a switching process in vehicles with an automated transmission, are provided by means of which (a) a target speed (n _{m, soll} ) of the vehicle engine in response to a synchronous speed (n _sync ) a newly set translation (u) of the transmission is determined; (b) dynamics of the torque build-up, based on a current engine speed (n _m ), an actual engine torque (md _m ) and a torque memory ( 22 ) stored past moments (md _hist ) and with the help of a predictor ( 18 ) is determined by the predictor ( 18 ) a presumed at the end of a prediction horizon (T _pred ) speed (n _est ) is output (prediction) and (c) the current speed (n _m ), the predicted speed (n _est ) and the target speed (n _{m, soll} ) are detected by a controller, the output of which is to be set via the engine control target torque (md _{m, soll} ) of the vehicle engine. Device according to claim 10, characterized in that the device comprises a limiter ( 20 ); the nominal torque (md _{m, soll} ) 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 ). Device according to one of the preceding claims 10 or 11, characterized in that the device has an interface ( 14 ) to a computation block for engine data ( 16 ) with the memory ( 22 ). Device according to one of the preceding claims 10 to 12, characterized in that the device is a torque memory ( 22 ), in which a torque history (md _hist ) is stored, which is included in the determination of the rotational speed (n _est ). Device according to one of the preceding claims 10 to 13, characterized in that the device comprises means with which the target speed (n _{m, soll} ) is increased during the switching operation according to a function (f) or ramped until the synchronous speed (n _sync ) or a synchronous speed (n _sync ) reduced by a predetermined value is achieved.