EGR Controller Variable Filter for Flow Stability
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Solution Overview
Problem
Conventional low-pressure EGR devices experience unstable control of EGR gas flow rate due to interference between EGR valve and intake throttle valve adjustments, leading to hunting and degraded responsiveness.
Innovation Solution
An EGR controller with a target value setting section, intake throttle valve opening degree computing section, EGR valve opening degree computing section, and filter processing section that applies a variable filter to correct and maintain the intake throttle valve opening degree, reducing interference and stabilizing control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If both EGR valve and intake throttle valve are concurrently adjusted to control EGR gas flow rate, then control precision is improved, but control stability deteriorates due to interference between adjustments
Solution Approach 1:
The control of EGR gas flow rate is segmented into two independent control loops: one controlling the EGR valve opening degree based on target EGR gas flow rate, and another controlling the intake throttle valve opening degree based on target EGR differential pressure. This segmentation eliminates interference between adjustments while maintaining control precision.
Solution Approach 2:
The EGR differential pressure serves as an intermediary parameter that mediates between the intake throttle valve control and the EGR gas flow rate control. By introducing this intermediate control variable, the system achieves stable control of both valves without direct interference.
2Stability of the object's composition
If either EGR valve or intake throttle valve control is dulled to ensure stable EGR gas flow rate control, then control stability is improved, but responsiveness deteriorates
Solution Approach 1:
The control system dynamically adjusts the opening degrees of both the EGR valve and intake throttle valve based on real-time feedback of actual EGR gas flow rate and EGR differential pressure. This dynamic control allows both valves to respond quickly to changes while maintaining stability through continuous feedback adjustment.
Solution Approach 2:
The system changes control parameters (target EGR gas flow rate and target EGR differential pressure) based on engine operation states, allowing optimal control responsiveness and stability under different operating conditions without dulling either control.
3Quantity of substance
If EGR valve opening degree is increased to increase EGR gas flow rate, then EGR gas flow rate is improved, but EGR differential pressure increases causing overshoot
Solution Approach 1:
The control system uses feedback from actual EGR differential pressure measurements to adjust the intake throttle valve opening degree. When EGR differential pressure increases due to EGR valve opening, the feedback loop automatically adjusts the throttle valve to maintain target pressure, preventing overshoot while preserving EGR gas flow rate increase.
Data Source
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AI summary
[Problem] To provide an EGR controller for an internal combustion engine and an EGR control method for the internal combustion engine that can maintain or improve responsiveness of EGR gas flow rate control while stably controlling an EGR gas flow rate. [Means for Resolution] An EGR controller 1 includes a target value setting section 2, an intake throttle valve opening degree computing section 3, an EGR valve opening degree computing section 4, a filter processing section 5, and an EGR device drive instructing section 6. The intake throttle valve opening degree computing section 3 computes a requested intake throttle valve opening degree. The EGR valve opening degree computing section 4 computes a requested EGR valve opening degree. The filter processing section 5 executes filter processing of the requested intake throttle valve opening degree computed by the intake throttle valve opening degree computing section 3 via a filter and computes an instructed intake throttle valve opening degree. In the filter processing, the requested intake throttle valve opening degree is maintained or corrected via the filter. The filter is a variable filter and is based on a difference between the requested intake throttle valve opening degree and the instructed intake throttle valve opening degree computed in the last filter processing and this requested intake throttle valve opening degree.