DE10311019A1 - Controlling torque of drive device involves generating control signal from instantaneous desired torque of drive device and target torque to be achieved after defined period - Google Patents

Abstract

The method involves generating a control signal (s) from an instantaneous desired torque (w) of the drive device (4) and a target torque (u) to be achieved after a defined period and controlling the drive device with the control signal to generate the torque. Partial control signals (s1,s2) derived from the desired torque and the target torque are combined to produce the control signal. An independent claim is also included for the following: an arrangement for controlling the torque of a drive device.

Description

The present invention relates relates to a method and a device for controlling a torque. In particular, it relates to a method and an apparatus for controlling a torque of an internal combustion engine via a Throttling device.

Coordinated in modern engine control units a moment structure desired Motor torques from internal and external requirements, for example from a transmission control. According to that from this coordination resulting target torque of the motor becomes the torque of the Motors controlled or regulated.

This is shown schematically in 3 shown. The desired target torque of a control or regulating device 10 fed. This generates an actuating signal sb from the target torque w. This control signal sb becomes a drive device 11 , for example an internal combustion engine, which influences the engine torque. This results in the generation of an actual torque y. The device can also be designed as a control loop. As an input variable for the control unit 10 the difference between the target torque w and the actual torque y is then used. This difference is from subtracting 5 educated.

An element of the drive device 11 , with which the engine torque is controlled, for. B be a throttle valve. The corresponding manipulated variable, which is controlled by the actuating signal sb, is then the opening angle of the throttle valve. Further possibilities for manipulated variables are, for example, the ignition timing of an air / gasoline mixture in a cylinder of the drive device or the air ratio (lambda).

For example, an increase in torque opens filling level the throttle valve or throttle device. The opening of the throttle device leads to an increase the cylinder filling and thus to an increasing engine torque.

In 4 such behavior is shown graphically. It shows curve 12 the target course of the opening angle of the throttle device and curve 13 the time course of the engine torque. The actual course of the opening angle is delayed compared to the target course. The engine torque increases again compared to the increasing opening angle of the throttle device and is filtered and filtered. Delay and filter effect are clearly noticeable when driving.

A faster follow-up behavior results when using the ignition timing as manipulated variable. this has but the disadvantage that this results in increased fuel consumption, since the ignition timing for the im Cylinder existing gasoline / air mixture is not optimal.

It is therefore an object of the present Invention, a method and an apparatus for controlling a To provide torque of a drive device, wherein the Torque follows a target torque as quickly as possible and on the other hand also a manipulated variable that the torque follows relatively slowly, used for control can be.

This task is solved by a method according to claim 1 or an apparatus according to claim 7. The dependent Expectations define advantageous or preferred exemplary embodiments of the method or the device.

According to the invention it is proposed that from a current target torque of the drive device and a target torque to be achieved after a certain period of time an actuating signal is generated, and that the drive device for Generation of the torque is controlled with the control signal.

Through the additional use of the after target torque to be reached within a certain period of time as an input variable for the control can have a significantly faster follow-up behavior of an actual torque to the target torque.

In particular, it is proposed that a first partial control signal from the target torque and from the Target torque a second partial control signal is generated and that the first control signal and the second control signal to the Control signal is combined.

The second partial control signal are advantageously formed such that a dead time and / or a Subsequent behavior of the drive device on the first partial control signal characterizing time constant, which when the Drive device occur only with the first partial control signal would be compensated.

The method according to the invention and the device according to the invention can be designed as a pure control or as a regulation be at the as additional Input variable for the control a current actual torque of the drive unit is used.

For example, in the case of a Internal combustion engine with the inventive method and the inventive device a throttle unit of the internal combustion engine for control or regulation of the torque can be controlled. This leads to a control, for example the ignition timing to reduced fuel consumption and made possible by the use of the method according to the invention or the device according to the invention nevertheless a quick control.

In addition to controlling the Throttle unit can continue the ignition timing or ignition angle changed the remaining deviations between the target torque and balance the actual torque. The deviation of the ignition timing from the optimal ignition timing However, it is significantly lower than the conventional one Control, so that the fuel consumption is hardly affected becomes.

The invention is described below Reference to the attached Drawing explained in more detail using a preferred embodiment. It demonstrate:

1 an embodiment of a device according to the invention,

2 simulated torque curves of a device according to the invention,

3 a device according to the prior art, and

4 a subsequent behavior of an engine torque on an opening angle of a throttle device.

1 shows the block diagram of an embodiment of an inventive device for controlling a torque of a drive device. A target torque w and a target torque u to be achieved after a certain period of time serve as input variables for the control. For example, transmission control of the drive unit may request a lower torque from the drive unit for a specific point in time. The duration of this torque reduction is known in advance. The size w then shows the currently desired torque, while the size u shows the target torque to be achieved after a certain period of time. Since the end of the torque reduction is known, the quantity u accordingly jumps back to the higher original torque earlier than the quantity w.

A first evaluation unit 1 generates a first actuating signal s1 from the setpoint torque w or from a setpoint torque signal supplied to it. A second evaluation unit also generates 2 a second setting signal s2 from the target torque u or from a target torque signal supplied to it. A summary facility 3 , for example an addition device, combines the partial actuating signals s1 and s2 to form an actuating signal s with which the drive device 4 is controlled. In this case, an opening angle of a throttle valve, an ignition timing of a spark plug or an air mixture as a manipulated variable can be influenced in particular by the control signal s. The drive unit 4 then generates an actual torque y.

The device can be designed both as a pure control and as a regulation. In the case of regulation, the target torque w and the actual torque y are preferably subtracted 5 supplied so that the difference between the target torque w and the actual torque y as an input variable for the first evaluation unit 1 serves. The first evaluation unit 1 is designed as a controller in this case. In principle, this can be any suitable controller. Different types of controller can also be used for increasing and decreasing the torque, for example a differentiating transmission element (D element) for increasing and a delay element of the first order (PT ₁ element) for reducing the torque.

The function of the evaluation devices is now described below 1 and 2 and the operation of the controller will be explained in more detail using an example. The mathematical functions shown below are given in the form of the so-called z-transform.

dargestellt werden. Dies stellt ein System mit einer Totzeit und einem Verzögerungsglied erster Ordnung dar. Die Verzögerung ist dabei im Wesentlichen durch ein mit der Drosselklappe verbundenes Saugrohr bestimmt. In Wirklichkeit stellt dies ein Verzögerungsglied höherer Ordnung dar, zur Veranschaulichung eignet sich der in Gleichung (1) dargestellte Prozess jedoch gut.The control of a throttle device, for example a throttle valve, for controlling the torque can be done for example by the process

being represented. This represents a system with a dead time and a first order delay element. The delay is essentially determined by an intake manifold connected to the throttle valve. In reality, this is a higher order delay, but the process shown in equation (1) is well suited for illustration.

The target torque leads the target torque by eight sampling or time steps: w (z) = z -8th u (z) (2)

For example, it is desirable to convert the target torque w (z) to the actual torque y (z) in accordance with a guide transmission behavior T (z), wherein

The transfer function of the first evaluation device 1 now with R (z) and the transfer function of the second evaluation device 2 denoted by S (z). Then for the in 1 illustrated Vorrich in the case of pure control: Y (z) = R (z) P (z) w (z) + S (z) P (z) u (z) (4)

For the first evaluation device 1 a simple proportional (P) controller is used, for example

Equations (1) to (4) then result in the transfer function for the second evaluation device 2 feedforward control:

For other transfer functions the transfer function S (z) must correspond to the first evaluation unit chosen differently become.

2 shows exemplary torque curves as a function of time for this exemplary embodiment. The curve poses 6 the course of the target torque u and the curve 7 represents the course of the target torque w. The curve 8th shows the course of the actual torque without the second evaluation unit 2 and the associated additional pilot control, the curve 9 shows the course of the actual torque with additional pilot control. This makes it clear that with the additional pilot control, the actual torque follows the target torque much faster and more precisely. The dead time and the dominant time constant, which results in a control without pilot control, is compensated for by the pilot control.

1

first evaluation

2

second evaluation

3

Combining means

4

drive unit

5

Subtract

6

course of the target torque

7

course of the target torque

8th

course of the actual torque without feedforward control

9

course of the actual torque with feedforward control

10

regulator

11

drive unit

12

course of the opening angle a throttle valve

13

course of the actual torque

w

target torque

u

target torque

y

actual torque

s1

first Part positioning signal

s2

second Part positioning signal

s

actuating signal

sb

actuating signal

t

time

Claims (12)

Method for controlling a torque (y) of a drive device ( 4 ), characterized in that from a current target torque (w) of the drive device ( 4 ) and a target torque (u) to be achieved after a certain period of time, an actuating signal (s) is generated and that the drive device ( 4 ) is controlled to generate the torque (y) with the control signal (s). Method according to claim 1, characterized in that a first partial control signal (s1) is generated from the target torque (w) of the drive device, that a second partial control signal (s2) is generated from the target torque (u), and that the first control signal (s1) and the second control signal (s2) are combined to form the control signal (s). A method according to claim 2, characterized in that the second partial control signal (s2) is formed such that a dead time and / or the subsequent behavior of the drive device ( 4 ) to the first partial control signal (s1) characterizing time constant, which would occur if the drive device were actuated solely with the first partial control signal (s1). Method according to one of the preceding claims, characterized in that the control signal (s) from an instantaneous actual torque (y) of the drive unit ( 4 ), the target torque (w) and the target torque (u) is generated. Method according to claims 2 and 4, characterized in that the first partial control signal (s1) from the difference between the Actual torque (y) and the target torque (w) is generated. Method according to one of the preceding claims, characterized characterized that the method of controlling the torque an internal combustion engine in a motor vehicle. Device for controlling a torque (y) of a drive device ( 4 ), characterized in that control means ( 1 . 2 . 3 ) are provided, to which a target torque signal, which describes a current target torque (w), and a target torque signal, which describes a target torque (u) to be achieved after a certain period of time, can be supplied, and that the control means ( 1 . 2 . 3 ) are designed in such a way that they generate an actuating signal (s) for controlling the drive device (s) from the target torque signal and the target torque signal ( 4 ) to generate the torque (y). Apparatus according to claim 7, characterized in that the control means ( 1 . 2 . 3 . 5 ) additionally an actual torque signal, which shows an instantaneous actual torque (y) of the drive device ( 4 ) describes, can be fed, and that the control means ( 1 . 2 . 3 . 5 ) are designed such that they additionally generate the control signal (s) from the actual torque signal. Device according to one of claims 7 or 8, characterized in that the control means ( 1 . 2 . 3 . 5 ) a first evaluation device ( 1 ) with a first transfer function for generating a first partial control signal (s1) from the setpoint torque signal, a second evaluation device ( 2 ) with a second transfer function for generating a second partial control signal (s2) from the target torque signal and a summarizing device ( 3 ) for generating the control signal (s) from the first (s1) and second (s2) partial control signal, and that the control of the drive unit ( 4 ) for generating the torque (y) has a third transfer function. Device according to one of claims 7 to 9, characterized in that that the drive device is an internal combustion engine with a throttle unit is and that the control signal (s) is a signal for control the degree of opening the throttle unit. Apparatus according to claim 8 and claim 10, characterized characterized in that the control means are designed such that they change the internal combustion engine in addition an ignition angle to make a difference between the target torque and equalize the actual torque. Device according to one of claims 7 to 11, characterized in that that the device to carry out of a method according to one of claims 1-6.