Exhaust Catalyst Temperature Control for Hydrocarbon Combustion
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Solution Overview
Problem
Existing exhaust purification apparatuses for internal combustion engines face increased complexity and component count due to the need for multiple passages or sensors, and methods for estimating hydrocarbon accumulation do not accurately account for adsorption efficiency, leading to potential fuel inefficiency and excessive temperature increases.
Innovation Solution
An exhaust purification apparatus that controls fuel ejection to increase the catalyst temperature only when particulate matter accumulation exceeds a threshold, using a single fuel injector and temperature sensor to manage hydrocarbon combustion, thereby avoiding unnecessary fuel consumption and maintaining the catalyst within a safe temperature range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If HC is adsorbed and accumulated in the DOC more than necessary to generate high temperature exhaust gas for DPF regeneration, then the temperature required for DPF regeneration is achieved, but the DOC exceeds the usable temperature and is likely to be degraded
Solution Approach 1:
The control means continuously monitors the temperature of the DOC and adjusts the fuel ejection timing and amount accordingly. When the DOC temperature approaches the usable limit, the system reduces fuel ejection or skips HC combustion events, preventing temperature exceedance and DOC degradation while still enabling DPF regeneration when conditions are appropriate.
Solution Approach 2:
The system dynamically adjusts the fuel ejection strategy based on real-time DOC temperature conditions. The control means modifies the ejection timing (before, during, or after combustion) and ejection amount to optimize temperature control, allowing flexible adaptation between preventing DOC degradation and achieving DPF regeneration temperature.
2Temperature
If fuel ejection is increased to raise catalyst temperature for HC combustion, then HC combustion is achieved, but the catalyst temperature may exceed the usable temperature range
Solution Approach 1:
The control means performs preliminary assessment of DOC temperature before initiating fuel ejection for HC combustion. By checking temperature conditions in advance and adjusting ejection timing accordingly, the system prevents excessive temperature rise while still achieving HC combustion when safe to do so, thereby protecting catalyst function.
3Reliability
If HC combustion is performed frequently to maintain adsorption efficiency, then adsorption performance is maintained, but fuel efficiency deteriorates due to excess fuel consumption
Solution Approach 1:
The control means uses feedback from temperature sensors to determine whether HC combustion is necessary. By monitoring actual DOC temperature and adsorption conditions, the system performs HC combustion only when needed to maintain adsorption efficiency, avoiding unnecessary fuel consumption and preserving fuel efficiency while maintaining catalyst 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 allows for accurate and timely combustion of hydrocarbons, preventing catalyst degradation while reducing the number of components and structural complexity, ensuring efficient fuel use and maintaining optimal operating temperatures.
Implementation Method 1
an adsorbent which adsorbs the HC contained in the exhaust gas
Implementation Method 2
oxidizing (combusting) the HC
Implementation Method 3
the accumulated HC is combusted
Implementation Method 4
a filter that is provided in the exhaust pipe downstream from the catalyst and collects particulate matter in exhaust gas
Data Source
Figure 1~2-2
Figure 2-3~3
Figure 4~6
AI summary
An exhaust purification apparatus for an internal combustion engine, which combusts hydrocarbon adsorbed to a catalyst at an appropriate timing while avoiding increase in the number of components and complexity of a structure thereof, is provided. There is provided an exhaust purification apparatus 14 for an internal combustion engine 10 in which a catalyst 15 capable of adsorbing and oxidizing hydrocarbon is provided in an exhaust pipe, the exhaust purification apparatus including temperature detection means 13 for detecting a temperature of the catalyst 15, estimation means 40 for accumulating a time during which the temperature of the catalyst 15 detected by the temperature detection means 13 is equal to or less than a predetermined temperature, and estimating an amount of hydrocarbon adsorbed on the catalyst 15 from the accumulated time, and control means 40 for controlling fuel ejection of the internal combustion engine 10 in a first ejection mode in which the temperature of the catalyst 15 is increased to a temperature where hydrocarbons adsorbed on the catalyst 15 are oxidized, in a case in which the amount of hydrocarbons estimated by the estimation means 40 exceeds a predetermined upper limit.