Method for adaptive control of the boost pressure of an internal combustion engine

Abstract

Method for adaptive control of the boost pressure of an internal combustion engine, comprising the following steps: - Definition of a target value for the boost pressure (S1); - Recording an actual value of the boost pressure (S2); - Recording a difference between the actual value and the target value (S3); - Control of the boost pressure with an integrating control component with the aim of aligning the actual value with the target value (S4); - Adaptation of the control when the amount of the difference is greater than a threshold value and when the actual value is greater than the setpoint value (S5), characterized in that the adaptation of the control takes place independently of the integrating control component.

Description

[0001] The invention relates to a method for adaptively controlling the boost pressure of an internal combustion engine according to the preamble of claim 1.

[0002] Control methods for boost pressure in internal combustion engines are known from the state of the art. So-called PID controllers are frequently used. These have a proportional control component, an integrating control component, and a differential control component. It is also known to use adaptive controllers. These allow the control to adapt to constant deviations between the actual and target boost pressure values. This allows, for example, component tolerances to be taken into account.

[0003] Typically, deviations that remain constant over time are initially compensated for by the integrating control component. After a certain period, the control system adapts so that this deviation no longer needs to be compensated for. Such adaptations occur relatively slowly.

[0004] Another problem with boost pressure control is so-called overshoot. These are relatively short but large differences between the actual value and the target value, where the actual value is greater than the target value. German patent DE 10 2006 032 835 B4 discloses the ability to adjust the differential control component when such an overshoot is detected. US patent US 6 497 223 B1 describes the use of an open-loop control controller to compensate for these overshoots.

[0005] DE 102 43 268 A1 discloses a method for controlling the turbocharging of an internal combustion engine, in which the manipulated variable generated from the control deviation between the setpoint and actual value of an operating parameter has an integral component for which a limit value is specified to prevent overshoot. An adaptive determination of this limit value is disclosed by adaptively correcting an operating parameter used to determine the limit value (the relative setpoint boost pressure) as a function of a second operating parameter (the engine speed).

[0006] DE 102 21 681 A1 discloses a method for controlling the speed of an internal combustion engine in a control loop, wherein the actual speed is recorded and converted into a filtered speed using a filter, from which a control deviation is calculated together with a target speed, which influences a speed controller. The method is characterized in that the filtered speed is monitored for speed oscillations, the frequency of which is compared with a first limit value upon detection in order to activate either a first mode for switching the filter or a second mode for adapting parameters of the speed controller, depending on the comparison.

[0007] In contrast, the invention is based on the objective of enabling rapid adaptation of the control system in the event of boost pressure overshoots.

[0008] This problem is solved by a method according to claim 1 and by a control device according to claim 10. Embodiments of the invention are specified in the dependent claims.

[0009] First, a target value for the boost pressure is defined, and an actual boost pressure value is recorded. Then, the difference between the actual value and the target value is measured. The boost pressure is then regulated using an integrative control component with the aim of aligning the actual value with the target value. An integrative control component, in this context, means that the control system includes a time-based integration of the difference between the actual value and the target value.

[0010] The control system adapts when the magnitude of the difference exceeds a threshold and when the actual value exceeds the setpoint. These two conditions are used as criteria for a boost pressure overshoot and must both be met simultaneously for adaptation to occur. The adaptation takes place independently of the integrating control component, resulting in particularly rapid adaptation. "Independent of the integrating control component" can mean, in particular, that the integrating control component does not trigger the adaptation. Alternatively or additionally, the adaptation can also modify parameters of other control components besides the integrating control component.

[0011] According to one embodiment of the invention, the adaptation can include adjusting at least one control parameter by or to a value determined before the difference is detected. Determining the value early enables rapid adaptation to compensate for the boost pressure overshoot as quickly as possible. The pre-determined value essentially serves to rapidly reduce the boost pressure to prevent damage to the internal combustion engine.

[0012] According to one embodiment of the invention, the actual value can be reduced more quickly by adapting the control independently of the integrating control component than without adapting the control.

[0013] According to one embodiment of the invention, the control system can have a proportional and a differentiating control component.

[0014] According to one embodiment of the invention, a deviation between the actual value and the setpoint, which is predominantly corrected by the integrating control component, can trigger a further adaptation of the control system. This further adaptation is therefore not independent of the integrating control component. In particular, this further adaptation can serve to adjust the control system to time-constant deviations, which are, for example, attributable to component tolerances. This further adaptation changes at least one parameter less significantly than the adaptation that is independent of the integrating control component.

[0015] A deviation that is predominantly regulated by the integrating regulatory component is understood in particular to mean that the deviation was regulated by the integrating regulatory component to more than 80%.

[0016] The two different adaptation methods ensure, on the one hand, a rapid response to a boost pressure overshoot and, on the other hand, a reliable adaptation to constant deviations over time.

[0017] According to one embodiment of the invention, the threshold value can be chosen such that exceeding it by the difference can result in damage to the internal combustion engine.

[0018] Damage is defined as the permanent or complete destruction of at least one component of the combustion engine due to excessive boost pressure. This ensures that adaptation only occurs when such damage is to be avoided. Otherwise, a slower adaptation is more advantageous.

[0019] According to one embodiment of the invention, after the adaptation of the control system, the boost pressure can be controlled using at least one adapted parameter.

[0020] According to one embodiment of the invention, the threshold value can be constant.

[0021] According to one embodiment of the invention, the threshold value can be changed depending on the actual value and / or the target value. This is particularly advantageous because, for example, smaller threshold values ​​can be selected for higher target values. At higher target values, damage to the combustion engine occurs even at smaller differences than at lower target values.

[0022] The control device according to claim 10 comprises an integrating control element configured for controlling the boost pressure with an integrating control component. Additionally, the control device may further comprise a differentiating and a proportional control element for a differentiating and a proportional control component, respectively.

[0023] Further features and advantages of the present invention will become clear from the following description of a preferred embodiment with reference to the accompanying figure.

[0024] Fig. Figure 1 shows a schematic flowchart of a method according to an embodiment of the invention.

[0025] In step S1, a target value for the boost pressure is defined. In step S2, an actual boost pressure value is recorded. In step S3, the difference between the actual value and the target value is then recorded. In step S4, the boost pressure is controlled using an integrating control component with the aim of aligning the actual value with the target value.

[0026] While the control process is running, step S5 simultaneously determines whether the magnitude of the difference exceeds a threshold and whether the actual value exceeds the setpoint. If both conditions are met, the control process running in step S4 is adapted. This adaptation occurs independently of the integrating control component. The adaptation can be achieved, for example, by changing a control parameter. The threshold can be constant or dependent on the setpoint and / or the actual value.

[0027] To ensure that the adaptation process is particularly quick, the parameter is preferably changed by or to a value that has already been predetermined.

[0028] The control process in step S4 can include not only an integrating control component but also a differentiating and a proportional control component. There may also be a further component in Fig.1. An adaptation not shown is provided, which is triggered by a deviation regulated by the integrating control component.

Claims

[1] Method for adaptive control of the boost pressure of an internal combustion engine, comprising the following steps: - Definition of a target value for the boost pressure (S1); - Recording an actual value of the boost pressure (S2); - Recording a difference between the actual value and the target value (S3); - Control of the boost pressure with an integrating control component with the aim of aligning the actual value with the target value (S4); - Adaptation of the control if the amount of the difference is greater than a threshold value and if the actual value is greater than the target value (S5), characterized by that the adaptation of the regulation occurs independently of the integrating regulatory component. [2] Method according to claim 1, characterized by , that the adaptation (S5) includes an adjustment of at least one parameter of the control by or to a value determined before the difference is detected. [3] Method according to any one of the preceding claims, characterized by, that the actual value is reduced more quickly through the adaptation (S5) of the control than without the adaptation (S5) of the control. [4] Method according to at least one of the preceding claims, characterized by that the regulation has a proportional and a differentiating regulatory component. [5] Method according to at least one of the three preceding claims, characterized by , that a deviation between the actual value and the setpoint, which is predominantly controlled by the integrating control component, triggers a further adaptation of the control, whereby the further adaptation changes at least one parameter less strongly than the adaptation independent of the integrating control component (S5). [6] Method according to at least one of the preceding claims, characterized by , that the threshold is chosen in such a way that exceeding it by the difference can result in damage to the internal combustion engine. [7] Method according to at least one of the preceding claims, characterized by , that after the adaptation (S5) of the control, the boost pressure is controlled with at least one adapted parameter. [8] Method according to at least one of the preceding claims, characterized by that the threshold is constant. [9] Method according to at least one of claims 1 to 7, characterized by that the threshold value is changed depending on the actual value and / or the target value. [10] Control device for controlling the boost pressure of an internal combustion engine, comprising an integrating control means, characterized by that the control device is configured to perform a method according to at least one of the preceding claims.

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