Exhaust Purification Catalyst with Oscillating Hydrocarbon Concentration
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Solution Overview
Problem
The existing internal combustion engine exhaust purification systems consume excessive hydrocarbons to achieve high NOX purification rates, which is inefficient.
Innovation Solution
The system incorporates an exhaust turbocharger with an exhaust purification catalyst and a hydrocarbon feed valve, utilizing precious metal catalysts on the catalyst's surface and a basic exhaust gas flow surface to vibrate hydrocarbon concentrations within specific ranges, allowing for two NOX purification methods: one for immediate removal and another for storage and release of NOX, with high and low-pressure exhaust gas recirculation systems to optimize hydrocarbon usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydrocarbons are continuously injected to maintain high NOX purification rate, then NOX removal efficiency is improved, but hydrocarbon consumption increases excessively
Solution Approach 1:
The patent applies periodic action by oscillating the hydrocarbon concentration within a predetermined range rather than maintaining continuous high concentration. The ECU controls the hydrocarbon feed valve to create periodic concentration variations that enable NOX purification while reducing overall hydrocarbon consumption. This is achieved by temporarily increasing hydrocarbon concentration during specific periods when NOX storage occurs in the catalyst, rather than maintaining constantly high levels.
Solution Approach 2:
The patent changes the parameter of hydrocarbon concentration from a static high level to a dynamic oscillating parameter within a predetermined range. The ECU monitors and adjusts the hydrocarbon concentration to vary within specific bounds, transforming the approach from continuous high consumption to controlled parameter variation that achieves the same purification effect with lower average consumption.
2Quantity of substance
If hydrocarbon concentration is increased to store more NOX in the catalyst, then NOX storage capacity is improved, but hydrocarbon usage efficiency deteriorates
Solution Approach 1:
The patent uses periodic action to oscillate hydrocarbon concentration within a predetermined range, enabling the catalyst to store NOX during high concentration periods and release it during low concentration periods. This periodic variation allows efficient NOX storage and release cycles without maintaining continuously high hydrocarbon levels, thus improving hydrocarbon usage efficiency while achieving adequate NOX storage capacity.
3Reliability
If exhaust gas recirculation is performed downstream of the exhaust turbine, then NOX purification is improved, but the system cannot respond quickly to acceleration operations
Solution Approach 1:
The patent segments the exhaust gas recirculation system into two distinct paths: a high-pressure EGR system that bypasses the exhaust turbine for rapid response during acceleration, and a low-pressure EGR system that recirculates gas downstream of the turbine for normal NOX purification. This segmentation allows the system to select the appropriate recirculation path based on operating conditions, achieving both rapid acceleration response and effective NOX purification.
Solution Approach 2:
The patent implements dynamic switching between high-pressure and low-pressure EGR systems based on acceleration detection. The ECU monitors acceleration operations and dynamically changes the EGR configuration, transitioning from low-pressure recirculation during normal operation to high-pressure recirculation during acceleration, thereby adapting the system behavior to operational requirements for both speed and purification performance.
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 reduces hydrocarbon consumption while maintaining high NOX purification rates, effectively managing NOX through controlled hydrocarbon concentration vibrations and recirculation strategies.
Implementation Method 1
exhaust purification catalyst which carries precious metal catalysts on exhaust gas flow surfaces
Implementation Method 2
basic exhaust gas flow surface parts are formed around the precious metal catalysts
Data Source
AI summary
An internal combustion engine wherein an exhaust purification catalyst and a hydrocarbon feed valve are arranged downstream in an exhaust passage. A first NOX purification method, which removes NOX by making a concentration of hydrocarbons that flows into the exhaust purification catalyst vibrate within predetermined amplitude and period ranges and a second NOX purification method which utilizes an adsorption action of NOX to the exhaust purification catalyst are used. A high pressure exhaust gas recirculation system (HPL) causing recirculation of high pressure exhaust gas and a low pressure exhaust gas recirculation system (LPL) causing recirculation of low pressure exhaust gas are provided. When performing an LPL recirculation while performing an NOX purification action by the second NOX purification method, if an acceleration operation occurs, the NOX purification action is switched to the NOX purification action by the first NOX purification method and recirculation is temporarily switched to the HPL recirculation.