DE19905420A1 - Regulating charging pressure for exhaust gas turbocharger involves continuously adapting regulator parameters depending on charging pressure control error or rate of change of control error - Google Patents

Abstract

The method involves regulating the charging pressure using at least one regulator acting upon a charging pressure demand value, whereby the regulator parameters are set using characteristic fields depending on operating parameters. The regulator parameters of at least one regulator are also continuously adapted depending on the control error between the actual charging pressure value and the demanded value or depending on the change in control error between the actual and demanded values.

Description

The invention relates to a boost pressure control method for an exhaust gas turbola which according to the preamble of claim 1.

Charging an internal combustion engine with an exhaust gas turbocharger is all common knowledge. An exhaust gas turbocharger consists essentially of the Main parts of the running gear, bearing housing, turbine and compressor housing. The rotor in turn consists of a turbine wheel with shaft and ver poet wheel. The turbine blades are for better boost pressure control often adjustable, for example pneumatic or electric. Usually the boost pressure actual value via controller, z. B. with a digital PI controller (Proportional-integral controller) or alternatively or additionally with a D- Controller or DT controller (differential controller) to a boost pressure setpoint regulated. Usually the controller parameters of the different are used Controllers depending on various characteristics or maps Operating values, such as speed, driving speed, gear stages, etc., certainly.  

However, the problem with such regulations is the constantly changing one Operating point or the constantly changing mode of operation, so that not a uniform controlled system characteristic can be assumed can. In addition, there are pronounced non-linearities and dead times of the Controlled system. So it is traditionally with an exhaust gas turbocharger adjustable turbine geometry not possible over the entire operation area or a satisfactory adjustment in all operating conditions maintain with high adjustment dynamics and homogeneous boost pressure build-up pass.

The object of the invention is to eliminate these disadvantages.

This object is achieved by the features mentioned in claim 1.

Accordingly, an inventive feature is to be seen in that the Control parameters of at least one controller additionally depending on the Control deviation between actual boost pressure value and desired boost pressure setpoint con be adjusted continuously.

The adaptation is preferably carried out by means of a map, in depending on the difference between the actual boost pressure value and the boost pressure A corresponding value is taken for an adjustment.

Alternatively, the input variable for the map can be changed to Difference or the rate of change of the difference between The boost pressure actual value and the boost pressure setpoint are switched off.

The above measure is described below using a differential Controller explained. This has the function of overshooting the charge pressure  kes when boost pressure builds up - and thus an excessive engine load - to prevent.

The differential controller accomplishes its task in that the output variable of the controller (D component) for an adjustment unit of the turbine blades (e.g. a vacuum converter or an electric motor) depending on the Ge Speed of the control deviation between the actual boost pressure value and the boost pressure setpoint is reduced. So if the actual boost pressure value at Accelerate to the boost pressure setpoint, the adjustment is already size for controlling the adjustment unit of the turbine blades adorns and the more the faster the boost pressure goes on. In order to adapt such a controller to the widest possible range To reach the entire operating area, it is necessary to Share already at the beginning of the boost pressure build-up and let it work.

By holding the differential controller in place, however, the potential goes of the variable exhaust gas turbocharger in the direction of charging as quickly as possible pressure buildup lost. In the worst case, there is even an overcompen station instead. However, the differential controller in the inventive manner adapted depending on the control deviation, it is possible in the range large control deviations, the D component in the interest of one if possible keep rapid boost build-up as low as possible or even negative adjust. Only shortly before the target pressure is reached, i.e. when the Re is small gel deviations, the D component is activated. With this measure is a significantly better adaptation of the controller to one by the Operating point-changing controlled system characteristic over the total control range possible.  

The present invention will now be described in a simple manner management example and explained in more detail with reference to the single drawing. The drawing shows a schematic block diagram for a control pair meter adaptation.

In the present case, the boost pressure is ge with a PID controller, not shown regulates. The PID controller has one input for the P gain, the I gain and the D gain, whereby due to the individual Ver degrees of strength an associated signal for the adjustment unit of the turbines blades of a variable exhaust gas turbocharger is generated. The respective ver strengthening, i.e. P-gain, I-gain and D-gain, results each from a map, namely a P map, an I map and a D map, from which according to the input of operation parameters A, the gain factors are read out as output values the.

The respective output values of the maps are then in each case assigned multiplication level changed, each with a P adaptation, an I adaptation and a D adaptation takes place. The respective adaptations in turn depend on operating parameters B, which are input variables in go through the corresponding adaptation procedures. The operating parameters A and B are each from a set of operations existing in the vehicle parameters.

In addition, there is a control deviation change in the differential adaptation tion read in due to the difference adaptation via multiplication affects the D component and thus the control process. With a suitable one The map component for the control deviation change is now the D component in changed the way that it is small with large control deviations, with small rule deviations is large, however. It is possible in the area  large control deviations, the fastest possible boost pressure build-up adjust. The boost pressure builds up shortly before reaching the Target pressure effectively braked.

Of course, parameters other than those of a differential Regulator be covered by the aforementioned parameter adaptation.

Claims (4)

1. boost pressure control method for an exhaust gas turbocharger with adjustable turbine blades, in which the boost pressure is regulated by means of at least one controller acting on an adjusting device to a boost pressure setpoint, the controller parameters being set via characteristic curves or characteristic diagrams depending on the operating parameters, thereby characterized in that the control parameter of at least one controller is additionally continuously adjusted as a function of the control deviation between the actual pressure and the desired pressure or depending on the change in the control deviation between the actual value and the desired pressure. 2. boost pressure control method according to claim 1, characterized, that the adaptation is carried out using a map.   3. boost pressure control method according to claim 1 or 2, characterized, that the controllers are a proportional controller (P controller), an integral controller (I controller), a differential controller (D controller) or a combination of such controllers. 4. Boost pressure control method according to one of the preceding claims che, characterized, that the influence of a differential controller is proportional to the control softening is changed.