Engine Intake Air Flow Control via Response Delay Model
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Solution Overview
Problem
Conventional control devices for internal combustion engines face challenges in accurately calculating target engine intake air flow quantities near the throttle valve, leading to errors and response delays, especially during transitional operations, due to neglecting volumetric efficiency and complex arithmetic expressions.
Innovation Solution
A control device that includes a throttle valve, operation state detecting means, intake air flow quantity detecting means, intake pipe internal pressure detecting means, and calculating units to determine actual and target intake air flow quantities, using a response delay model and phase lead compensation to accurately control the throttle opening degree and ensure swift convergence of actual cylinder intake air flow to the target.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional first-order lag filter model is used to calculate intake air flow quantity, then the calculation is simple, but the accuracy deteriorates during transitional operation due to neglecting volumetric efficiency
Solution Approach 1:
The patent changes the parameters of the calculation model by introducing volumetric efficiency equivalent values and response delay model parameters. Instead of using a simple first-order lag filter, the invention incorporates additional parameters (volumetric efficiency, intake pipe volume, cylinder displacement) to accurately represent the physical characteristics of the intake system, thereby improving calculation accuracy during transitional operations.
Solution Approach 2:
The patent introduces a response delay model as an intermediary between the throttle valve position and the actual cylinder intake air flow quantity. This model acts as a mediator that accounts for the time delay and physical characteristics of air flow through the intake system, allowing accurate calculation of cylinder intake air flow based on throttle position and volumetric efficiency without requiring complex real-time measurements.
2Speed
If the target cylinder intake air flow quantity is calculated without phase lead compensation, then the calculation is straightforward, but the response speed deteriorates during transitional operation
Solution Approach 1:
The patent applies phase lead compensation to the target cylinder intake air flow quantity calculation in advance. By predicting the required air flow with phase lead compensation before actual throttle adjustment, the system anticipates the response delay of the intake system and adjusts the target value accordingly, enabling faster and more accurate throttle response during transitional operations.
3Measurement precision
If volumetric efficiency equivalent value is not considered, then the calculation method is simple, but the accuracy of air flow quantity deteriorates in engines with variable valve mechanisms
Solution Approach 1:
The patent incorporates volumetric efficiency equivalent values as key parameters in the calculation model. By using the relationship between engine operating conditions (rotational speed, intake pipe pressure) and volumetric efficiency, the invention accurately determines the actual cylinder intake air flow quantity without requiring complex direct measurements, thus maintaining ease of operation while improving accuracy.
Data Source
AI summary
Provided is a control device for an internal combustion engine, which is provided to allow a throttle opening degree to be controlled in accordance with a target engine intake air flow quantity even during transitional operation. The actual cylinder intake air flow quantity calculating unit (21) calculates a response delay model for an intake system from a volumetric efficiency equivalent value (Kv) calculated from a rotational speed (Ne) of an engine (1) and an intake manifold pressure (Pim), an intake pipe volume (Vs), and a displacement (Vc) of each of cylinders (2), and calculates an actual cylinder intake air amount (Qcr) from an actual engine intake air amount (Qar) obtained from an air flow sensor (4) and the response delay model. The intake air flow quantity controlling unit (24) controls the throttle opening degree (TP) in accordance with the target engine intake air amount (Qat).