WO2013037551A1

WO2013037551A1 - Method and device for control path modification

Info

Publication number: WO2013037551A1
Application number: PCT/EP2012/064417
Authority: WO
Inventors: Bernhard Ledermann; Claudius Bevot; Thomas Schulz; Rolf Reischl; Thomas Braun; Ruediger Fehrmann; Ralf Kraemer
Original assignee: Robert Bosch Gmbh
Priority date: 2011-09-14
Filing date: 2012-07-23
Publication date: 2013-03-21
Also published as: EP2756180B1; EP2756180A1; JP5931201B2; CN103782015A; JP2014530313A; DE102011082641A1; CN103782015B

Abstract

The invention relates to a method for the control path modification of a lambda control system, which is connected on the input side to an exhaust gas probe, and wherein a dynamic behavior and/or dead time behavior that varies as a result of the probe construction, of a manufacturing tolerance, of a variable probe temperature, or of aging is taken into consideration and the control behavior of the lambda control system is adapted accordingly. According to the invention, it is provided here that by means of a purely software-based adaptation, the control behavior of the lambda control system is adapted to the design of different exhaust gas probes and the dynamic characteristic thereof. The invention further relates to a corresponding device for carrying out the method. Using the method and the device for carrying out the method, different commercially available exhaust gas probes can be operated with the same control apparatus hardware. The different dynamic characteristics of the exhaust gas probes are reproduced here using different adaptable feedbacks. This is particularly advantageous in terms of a standardized hardware platform in engine control apparatuses for combustion engines and thus with a view to the costs.

Description

description

title

Method and device for controlled system modification Prior art

The invention relates to a method for controlled system modification of a

Lambda controller, which is on the input side with an exhaust gas probe in connection and taking into account a result of the probe design, a specimen scattering, a variable probe temperature or aging changing dynamic behavior and / or dead time behavior and the control behavior of the lambda control is adjusted accordingly.

The invention further relates to a device for carrying out the

inventive method.

Legal regulations prescribe the monitoring of the composition of the exhaust gas of internal combustion engines for compliance with limit values. For this purpose, unwanted substances such as nitrogen oxides and carbon monoxide are converted in the exhaust gas by means of controlled three-way catalysts in uncritical to see substances such as water vapor, carbon dioxide and nitrogen. This conversion requires that the internal combustion engine supplied air-fuel mixture in a certain

Composition range lies around a stoichiometric composition. This is designated by the parameter lambda = 1. The composition of the air-fuel mixture is monitored with provided in the exhaust passage of the internal combustion engine exhaust gas sensors, for example in the form of broadband lambda probes that determine the oxygen partial pressure. The correct function of the exhaust gas sensors and in particular their aging resistance depend heavily on their electronic shear circuit. The functional blocks of such a circuit are described by way of example in document DE 10 2006 061 565 A1.

Of particular importance is the lambda control, whereby the exhaust gas probes available on the market have different characteristics with regard to the

Response dynamics and the dead times may have.

In order to ensure a stable control must, for example, built in engine control units lambda controller with additional electronic

Beschaltungen be supplemented when exhaust probes, in particular of

different providers, be installed. In contrast, vehicle manufacturers demand a uniform ECU hardware for all probes.

A wide variety of control strategies are known from the prior art, in which adaptive controller interventions are also used.

In DE 3727369 A1, for example, a control system is described in which a changeover of the control behavior is made possible by analyzing a desired / actual comparison. The preferred embodiment provides for switching between different controller characteristics. The control system provides in particular for use in a lambda control and allows a good

Compensation of occurring disturbing influences by suitable switching of the

Controller behavior.

From DE 19844994 A1, a compensation of the dynamic behavior of the lambda probe is described in connection with a dynamic diagnosis of a lambda probe, wherein an adaptable feedback to the lambda controller is provided. Described is u.a. a block BL1 in which a model of the

Controlled system is stored, which allows a compensation of the dynamic behavior of the controlled system. From this compensation of the track behavior conclusions can be drawn on a change in the delay time of the lambda probe.

DE 10 2008 001 569 A1 relates to a method and a device for adapting a dynamic model of an exhaust gas probe, which is part of an exhaust gas duct of a Internal combustion engine is and with a lambda value for controlling an air-fuel composition is determined, wherein in a control device or in a diagnostic device of the internal combustion engine, a simulated lambda value is calculated in parallel and both the simulated and the measured lambda value is used by a user function , According to the invention, it is provided that, during ongoing vehicle operation, by evaluating a signal change upon excitation of the system, a jumping behavior of the exhaust gas probe is determined and the dynamics model of the exhaust gas probe is adapted on the basis of these results. The invention serves to determine the actual response of the exhaust gas probe and the correction of the model parameters of the calculated lambda value, and thus to improve the match of measured and modeled lambda value, as long as this makes sense from the point of view of the user function. For this purpose, the results of the step responses are collected and sorted into categories according to specific criteria. The main criterion here may be the exhaust gas mass flow, since the response of the exhaust gas probe and the gas transit time depend essentially on this size.

An adaptation to differently installed exhaust gas probes, with the objective of being able to use a universal controller, is described in the above mentioned. Writings not revealed.

It is therefore an object of the invention to provide a method for controlled system modification, with which a universal controller used and thus an adaptation to differently installed exhaust gas sensors can be made possible.

It is a further object of the invention to provide a corresponding device for

To provide implementation of the method.

Disclosure of the invention

The object relating to the method is achieved in that by means of a pure software adaptation, the control behavior of the lambda controller to the structure

different exhaust gas sensors and their dynamic characteristics is adapted.

The object relating to the device is achieved in that the lambda controller is designed as a digital PID controller and by means of a pure software adaptation the Control behavior of the lambda controller to the structure of different exhaust gas sensors and their dynamic characteristics is adaptable, these facilities for

Implementation of the method according to the invention with its variants. With the method and the device for carrying out the method can be different, available on the market exhaust probes with one and the same

Control device hardware to be operated. The different ones

Dynamic characteristics of the exhaust gas probes are simulated by various adaptable feedbacks. This is particularly advantageous in terms of a standardized hardware platform in engine control units for internal combustion engines and thus in terms of cost. In addition, stabilizing measures can be taken during operation by the software adaptation, according to the

Requirements to be performed. A preferred variant of the method provides that a digital PID controller is used as lambda controller and an output signal of the controller is fed back and added to the input differential signal, wherein the entire controller output or parts of the controller characteristic of the controller with a predeterminable

Gain multiplied and fed back. With this measure, for example, instabilities, which at certain exhaust probes due to your

Design can occur, be compensated and adjusted accordingly.

Additional connections on the exhaust gas probe or between the exhaust gas probe and

Lambda controllers, such as RC elements, can be omitted. The

stabilizing effect can be completely simulated by the digital PID controller. In addition to the elimination of such RC elements can also on

Abschaltvorrichtungen, which can cause additional residual currents can be omitted, which would otherwise be required to operate different exhaust gas probes on a lambda controller. In addition, disturbing influences on one

Internal resistance measurement of the exhaust gas probe during adjustment and / or on a

Reference pump flow of the exhaust probe can be avoided.

It can be provided that a PI, PD, DI, P, I or D component is coupled back as part of the controller characteristic. Which part of the controller characteristic is fed back depends on the connected probe type. Simulations can help to provide the optimal feedback case for each type of probe determine. For example, when using a probe with a long dead time, it could be determined that a feedback of the P component in conjunction with a D component for such exhaust gas probes led to the best results for controller stability. For other probes with a different characteristic, such

Feedback can also be withdrawn or applied only to a small extent. Thus, the control system can be adapted to almost all available on the market exhaust gas sensor types quite cheaply, which is advantageous in terms of high flexibility both the vehicle manufacturer and the repair shop.

It is provided in a preferred variant of the method that the

Output signal of the digital PID controller is fed back with an applicable factor smaller than 1 and the feedback is taken into account in a next time step of the digital PID controller. This can be particularly beneficial to the

Lambda control effect.

In applications with certain exhaust probes stabilization problems may arise, which is caused by a gas flow dead time of the controlled system of this probe type. A hardware fix in the form of a high pass between an APE electrode and a reference electrode (RE) of the exhaust probe and a high D component would solve the problem. However, the evaluation in this case is quite susceptible to interference. Therefore, an advantageous variant of the method provides that a broadband lambda probe with a Nernst cell and a pump cell is used as the exhaust gas probe, wherein the dead time is compensated as a result of the gas transit time by means of a direct electrical feedback, which

Pumping current change at the pump cell immediately proportional and integrating on a reference electrode passes. This stabilizes the pumping current control without the need for additional wiring or a D-component. A preferred application of the method, as described above in its variants, provides for the use of controlled system modification in one

Lambda evaluation ASIC, as a digital PID controller as part of a

Lambda control of an internal combustion engine is formed. Such a lambda evaluation ASIC is known, for example, as the "CJ 135 Lambda Probe Interface IC" by the applicant, to which different exhaust gas probes are connected can and can generally be part of a higher-level engine control. Additional shading is not necessary when using the method described above, if in the production of the vehicle different exhaust gas sensors are installed by different manufacturers.

The invention will be explained in more detail below with reference to an embodiment shown in the figure. It shows:

Figure 1 shows a schematic representation of a digital controlled system with a

feedback share.

FIG. 1 shows a detail of a lambda controller 1 to which an exhaust gas probe can be connected. Such lambda controllers 1 are known, for example, as "CJ 135 Lambda Probe Interface IC." This includes a PI D controller 10, which has a proportional-action P-controller train 14, an integral-action I-controller train 15, and a D-controller. Regulator line 16 for a differential component in its controlled system, which on the output side by means of an adder 17th

summarized and are available as an output signal 18. According to the invention is provided, as the example in Figure 1 shows that a

Feedback of the P component of the PI D controller 10 is switched to an input variable 1 1, wherein the P component of the PI D controller 10 multiplied in an amplification unit 20 with an applicable factor, usually less than 1, by means of an integrator 21st integrated and subtracted from the input 1 1 by means of a subtractor 13.

The o.g. Functionality is particularly advantageous as a pure software solution in the

Lambda controller 1 implemented. A typical application describes the following application example. Flue gas probes from certain suppliers can usually be operated stably on a PI D digital controller, such as the CJ 135 module already mentioned above, only with additional RC circuitry. Other exhaust gas sensors, including those of the applicant, however, do not need this high pass. On the other hand, these probes can not be operated with this high-pass filter, because thereby the internal resistance measurement is unduly impaired. Since the vehicle manufacturers require a uniform ECU hardware for all probes, the high pass must be provided with a shutdown device. This is associated with other, already mentioned above disadvantages. The measure according to the invention, in which a stabilizing effect of the controlled system is modeled, can also be operated on the CJ 135 module without additional electrical connections and gas probes. The adaptation of the control unit to the probe type is now possible by a pure software adaptation.

Claims

claims

1 . Method for controlled-system modification of a lambda controller (1), which

On the input side is connected to an exhaust gas probe and in which a result of the probe construction, a specimen scattering, a variable

Probe temperature or aging dynamic behavior and / or deadtime behavior taken into account and the control behavior of the lambda controller (1) is adjusted accordingly, characterized in that by means of a pure software adaptation, the control behavior of the lambda controller (1) is adapted to the structure of different exhaust probes and their dynamic characteristics.

2. The method according to claim 1, characterized in that as a lambda controller (1) uses a digital PID controller (10) and an output signal (18) of the controller is fed back and added to the input differential signal, wherein the entire controller output or parts of the controller characteristic of the controller multiplied by a predeterminable gain factor and fed back.

3. The method according to claim 2, characterized in that as part of

Controller characteristic, a PI, PD, DI, P, I or D component is coupled back.

4. The method according to any one of claims 1 to 3, characterized in that the output signal of the digital PID controller (10) is fed back with an applicable factor less than 1 and the feedback (19) in a next time step of the digital PID controller (10 ) is taken into account.

5. The method according to any one of claims 1 to 3, characterized in that a broadband lambda probe with a Nernst cell and a pumping cell is used as the exhaust gas probe, wherein a dead time due to a gas running time by means of a direct electrical feedback (19) is compensated, which a pumping current change to the pumping cell immediately proportional and integrating on a reference electrode passes. Application of the method according to one of claims 1 to 5 to

Control path modification in a lambda evaluation ASIC, which is designed as a digital PID controller (10) as part of a lambda control of an internal combustion engine.

Device for controlled-system modification of a lambda controller (1), which is connected on the input side to an exhaust gas probe and in which, as a consequence of the probe design, a specimen scattering, a variable

Probe temperature or aging dynamic behavior and / or deadtime response taken into account and the control behavior of the lambda controller (1) is adjusted accordingly, characterized in that the lambda controller (1) as a digital PID controller (10) is formed and by means of a pure

Software adaptation, the control behavior of the lambda controller (1) to the structure of different exhaust gas probes and their dynamic characteristics can be adapted, this means for performing the method according to the method claims 1 to 5.