Exhaust Catalyst Hydrocarbon Injection Control
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Solution Overview
Problem
Current internal combustion engine exhaust purification systems achieve high NOX purification rates but seek further improvement, especially at high catalyst temperatures where the NOX purification rate decreases.
Innovation Solution
An exhaust purification system with a hydrocarbon feed valve and an exhaust purification catalyst downstream, where precious metal catalysts on the catalyst surfaces interact with hydrocarbons whose concentration is vibrated within specific amplitude and period ranges, optimizing the deposition and storage of hydrocarbons to enhance NOX reduction, and controlling hydrocarbon injection to maintain these conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the concentration of hydrocarbons flowing into the exhaust purification catalyst is kept high, then the NOX purification rate is improved, but the storage amount of NOX in the catalyst decreases
Solution Approach 1:
The patent applies periodic action by controlling the hydrocarbon feed valve to periodically inject hydrocarbons into the exhaust passage. This creates periodic vibrations in the hydrocarbon concentration that flows into the exhaust purification catalyst. The periodic injection timing and amount are controlled to maintain hydrocarbon concentration within a specific range, which simultaneously achieves high NOX purification rate and maintains adequate NOX storage capacity in the catalyst.
2Quantity of substance
If the vibration period of hydrocarbon concentration is extended, then the storage amount of NOX is increased, but the NOX purification rate decreases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the injection timing and amount of hydrocarbons from the feed valve. This control maintains the hydrocarbon concentration vibrations within a specific range of parameters (amplitude and period). By optimizing these parameters, the system achieves a balance where the vibration period is sufficient to maintain NOX storage while the amplitude and timing ensure high NOX purification rate.
3Productivity
If the deposition ability of hydrocarbons to the downstream side part is increased, then the NOX purification rate is improved, but the uniformity of hydrocarbon distribution along the catalyst length is reduced
Solution Approach 1:
The patent applies local quality by creating different hydrocarbon concentration conditions at different locations along the catalyst. The upstream side receives hydrocarbons with moderate deposition ability to maintain adequate concentration and prevent complete consumption. The downstream side has higher deposition ability to ensure sufficient hydrocarbon availability for NOX reduction. This spatial differentiation of deposition ability optimizes the overall 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 maintains an extremely high NOX purification rate across varying catalyst temperatures, including high temperatures, by effectively using hydrocarbons to reduce NOX through controlled concentration and injection timing, reducing nitrate formation and enhancing the catalyst's NOX storage capacity.
Implementation Method 1
an exhaust purification catalyst for reacting NOx contained in an exhaust gas and reformed hydrocarbons is arranged in the engine exhaust passage downstream of the hydrocarbon feed valve, precious metal catalysts are carried on exhaust gas flow surfaces of the exhaust purification catalyst
Implementation Method 2
the exhaust purification catalyst is formed so that a deposition ability of hydrocarbons to a downstream side part of the exhaust purification catalyst becomes higher than a deposition ability of hydrocarbons to an upstream side part of the exhaust purification catalyst
Data Source
AI summary
An internal combustion engine wherein a hydrocarbon feed valve (15) and an exhaust purification catalyst (13) are arranged inside of an engine exhaust passage. At the time of engine operation, the amount of injection of hydrocarbons from the hydrocarbon feed valve (15) is controlled so that an amplitude of change of concentration of hydrocarbons which flow into the exhaust purification catalyst (13) becomes within a predetermined range of amplitude, and the injection period of hydrocarbons from the hydrocarbon feed valve (15) is controlled so that a concentration of hydrocarbons which flow into the exhaust purification catalyst (13) vibrates within a predetermined range of period. The exhaust purification catalyst (13) is formed so that a deposition ability of hydrocarbons to a downstream side part of the exhaust purification catalyst (13) becomes higher than a deposition ability of hydrocarbons to an upstream side part of the exhaust purification catalyst (13).