Adaptive regulation
Machine operation

Adaptive regulation

Adaptive regulation Among the many control systems used in modern vehicles, most are those that can adapt to changing conditions. This is called adaptive control systems. A typical example of such a solution is the regulation of the fuel dose in an engine with electronically controlled petrol injection. Injection time correction

At any time during the operation of the engine, the controller is based on two main values, namely the shaft speed. Adaptive regulationcrankshaft and engine load, i.e. the value of the pressure in the intake manifold or the mass of the intake air, is read from the memory of the so-called. base injection time. However, due to the many changing parameters and the influence of various factors affecting the composition of the fuel mixture, the injection time must be adjusted.

Among the many parameters and factors that affect the composition of the mixture, it is possible to accurately measure the influence of only a few. These include, but are not limited to, engine temperature, intake air temperature, system voltage, throttle opening and closing speeds. Their influence on the composition of the mixture is determined by the so-called short-term injection correction factor. Its value is read from the controller's memory for the measured current value of each of the selected values.

After the first, the second correction of the injection time takes into account the total influence of various factors on the composition of the mixture, the individual influence of which is difficult or even impossible to measure. These include, but are not limited to, errors in correcting the effect on the composition of the mixture of selected values ​​measured by the controller, differences in fuel composition or quality, injector contamination, engine wear, intake system leakage, atmospheric pressure change, engine damage, which the on-board diagnostic system cannot detect and they affect the composition of the mixture.

The combined influence of all these factors on the composition of the mixture is determined by the so-called correction factor for long injection times. Negative values ​​of this parameter, as in the case of a short-term correction factor, mean a decrease in injection time, a positive increase and zero injection time correction. The operation of the engine, determined by the speed and load, is divided into intervals, each of which is assigned one value of the correction factor for long injection times. If the engine is in the starting phase, at the beginning of the warm-up phase, running at a constant heavy load, or must accelerate rapidly, the injection timing procedure is completed with the last correction using the long-term injection time correction factor.

Fuel Dose Adaptation

When the engine is idling, in the light to medium load range or under gentle acceleration, the injection time is again controlled by signals from the oxygen sensor, i.e. the lambda probe, located in the exhaust system before the catalytic converter. The composition of the mix, which is influenced by many factors, can change at any time, and the controller may not recognize the reason for this change. The controller then looks for an injection time that will provide the best mixture possible. This checks whether the change range of the instantaneous injection time correction factor is within the correct range.

If so, this means that the injection time value determined after the second trim is correct. However, if the values ​​of the instantaneous injection time correction factor were outside the allowable range for a certain number of engine cycles, this proves that the influence of the factors causing the change in the composition of the mixture is constant.

The controller then changes the value of the long-term injection time correction factor so that the instantaneous injection time correction factor is again within the correct values. This new value for the long-term injection time correction factor, obtained by adapting the mixture to the new, changed engine operating conditions, now replaces the previous value for this operating range in the memory of the controller. If the engine is again under these operating conditions, the controller can immediately use the long-term correction of the injection time value calculated for these conditions. Even if it is not perfect, the time to find the optimal dose of fuel will now be significantly less. Because of the process of creating a new value of the long-term injection time correction factor, it is also called the injection time adaptation factor.

Advantages and disadvantages of adaptation

The process of adapting the injection time allows you to continuously adjust the dose of fuel depending on the change in fuel demand during operation. The result of the injection time adaptation process is the so-called injection time customization, developed by the manufacturer and stored in the controller's memory. Thanks to this, it is possible to fully compensate for the influence of both deviations in characteristics and slow changes in the technical condition of the system and the entire engine.

Adjustment of the adaptive type may, however, result in errors that occur being hidden or simply adapted, and then become difficult to recognize. Only when, as a result of a larger failure, the adaptive control process is so seriously disturbed that the system goes into emergency operation, it will be relatively easy to find a malfunction. Modern diagnostics can already deal with the problems that arise as a result of adaptation. The control devices that have adapted the control parameters fix this process, and the parameters stored in the memory accompanying subsequent adaptation changes make it possible to identify the malfunction in advance and unambiguously.

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