Exhaust Gas Purification System Dynamic Temperature Control
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Solution Overview
Problem
In exhaust gas purification systems for internal combustion engines, temperature control during regeneration processing can lead to insufficient temperature increment, overshooting, heat degradation, and erosion of catalysts due to varying oxygen concentrations and excess air ratios, which affect the heat generation in different catalyst devices.
Innovation Solution
The system includes an oxidation catalyst device upstream and a lean NOx trap catalyst device downstream, with a controller that adjusts the measurement position of the control temperature based on oxygen concentration to optimize temperature-rising control, using multiple temperature sensors and threshold settings to ensure the control temperature reflects the catalyst device with the highest heat generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the control temperature is set based on a fixed catalyst device (e.g., oxidation catalyst) to ensure responsiveness, then the temperature control is simple and responsive, but insufficient temperature increment or overshooting occurs when another catalyst device (e.g., lean NOx trap) generates more heat
Solution Approach 1:
The patent applies dynamics by making the control temperature measurement position variable rather than fixed. The controller dynamically selects which catalyst device's temperature to use as the control target based on real-time heat generation conditions. This allows the system to adapt to changing operational states where different catalysts generate varying amounts of heat, ensuring reliable temperature control for regeneration across all conditions while maintaining responsiveness.
Solution Approach 2:
The patent changes the parameter of control temperature measurement position based on excess air ratio and oxygen concentration. By adjusting which temperature measurement is used as the control target according to these parameters, the system optimizes temperature control for the currently active heat-generating catalyst, preventing both insufficient heating and overshooting while maintaining system responsiveness.
2Measurement precision
If the control temperature measurement position is changed according to oxygen concentration and excess air ratio, then temperature control accuracy is improved and regeneration reliability is enhanced, but the control system complexity increases
Solution Approach 1:
The controller dynamically adjusts the control temperature measurement position based on detected oxygen concentration and excess air ratio. This dynamic adaptation allows the system to select the most appropriate temperature measurement (from among multiple catalyst devices) to serve as the control target, improving measurement accuracy and regeneration reliability without requiring complex additional hardware.
Solution Approach 2:
The system uses feedback from oxygen concentration sensors and excess air ratio measurements to determine which catalyst device's temperature should be used as the control target. This feedback mechanism enables the controller to automatically select the appropriate temperature measurement position, achieving high measurement precision while keeping the control logic manageable through rule-based decision making.
3Ease of operation
If a fixed catalyst device is used for temperature control, then the control system is simple to operate, but temperature increment may be insufficient for catalysts downstream when upstream catalysts dominate heat generation
Solution Approach 1:
The system dynamically selects the control temperature measurement position based on which catalyst is currently generating the most heat, as indicated by oxygen concentration and excess air ratio. This ensures that the temperature control targets the correct catalyst, providing sufficient temperature increment to the heat-generating catalyst and its downstream catalysts, while maintaining operational simplicity through automated selection.
Solution Approach 2:
The control system changes the measurement position parameter based on oxygen concentration and excess air ratio. When these parameters indicate high oxygen levels (suggesting upstream oxidation catalyst dominance), the system selects that catalyst's temperature; when oxygen levels are low (suggesting downstream lean NOx trap dominance), it selects the downstream catalyst's temperature. This ensures adequate temperature increment for the active heat-generating catalyst.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach prevents insufficient temperature increment, overshooting, and heat degradation, allowing for reliable regeneration processing by optimizing temperature control according to oxygen concentration and excess air ratio, thereby maintaining catalyst effectiveness.
Implementation Method 1
the temperature relating to the catalyst device in which the heat generation amount by the combustion of unburned hydrocarbon (HC) supplied to increase a temperature is largest
Data Source
AI summary
An exhaust gas purification system for an internal combustion engine includes an oxidation catalyst device on an upstream side in an exhaust passage of an internal combustion engine and a lean NOx trap catalyst device on a downstream side, a controller which controls the exhaust gas purification system is configured to, when a temperature-rising control of an exhaust gas in a regeneration control is performed to recover a purification ability of the exhaust gas purification system, perform a control that changes a measurement position of a control temperature which is a control amount of a feedback control in the temperature-rising control, according to an excess air ratio or an oxygen concentration of the exhaust gas passing through the exhaust passage.