Exhaust Purification Filter with Periodic Secondary Air Control
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Solution Overview
Problem
Existing exhaust purification systems fail to maintain high catalyst temperatures for effective combustion of soot due to continuous secondary air supply, leading to inadequate removal of harmful components like HC and CO.
Innovation Solution
A system that controls secondary air supply with a predetermined frequency and oxygen concentration amplitude to create a cycle of lean and non-lean states, maintaining catalyst temperature and promoting combustion through adsorption and oxidation heat cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If secondary air is continuously supplied to the filter, then oxygen is provided for soot combustion, but the exhaust gas temperature decreases and soot combustion is inadequate
Solution Approach 1:
The patent applies periodic action by controlling the secondary air supply to oscillate at a specific frequency (0.05-2 Hz) rather than continuous supply. This periodic injection creates cycles of oxygen concentration variation that allow the catalyst to alternately adsorb oxygen during lean phases and release it during rich phases, maintaining catalyst temperature while providing necessary oxygen for soot combustion
2Productivity
If secondary air is supplied with high frequency, then oxygen is provided more frequently, but the catalyst temperature fluctuates excessively and combustion efficiency decreases
Solution Approach 1:
The patent applies parameter changes by optimizing the frequency parameter of secondary air supply to a specific range (0.05-2 Hz). This parameter optimization ensures that the oscillation frequency matches the catalyst's oxygen storage and release characteristics, maintaining stable catalyst temperature while achieving effective oxygen supply for soot combustion
3Quantity of substance
If secondary air amplitude is increased to promote soot combustion, then more oxygen is available, but the temperature drops further and purification efficiency decreases
Solution Approach 1:
The patent uses periodic action with controlled amplitude (0.5-5% oxygen concentration variation) to create optimal oscillation cycles. The periodic injection pattern with specific amplitude ensures sufficient oxygen availability during lean phases while limiting temperature drop, allowing the catalyst to maintain combustion functionality
4Reliability
If the catalyst operates continuously in lean state, then oxygen storage capacity is maintained, but the cycle of adsorption and oxidation reactions cannot be generated and catalyst activity decreases
Solution Approach 1:
The patent applies periodic action by creating controlled oscillations between lean and rich states through frequency-controlled secondary air injection. This periodic variation enables the catalyst to cycle between oxygen adsorption (during lean phases) and oxygen release with oxidation reactions (during rich phases), maintaining both oxygen storage capacity and catalytic activity
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
Enhances the purification of HC and CO by maintaining high catalyst temperatures, reducing T50 values by 5°C or more, thereby improving purification efficiency.
Implementation Method 1
the exhaust purification catalyst generates adsorption heat by adsorbing O2 if the air-fuel ratio of the exhaust gas is leaner than the stoichiometric air-fuel ratio
Implementation Method 2
generates oxidation heat by oxidizing HC and CO using the adsorbed O2 if the air-fuel ratio of the exhaust gas is not lean
Implementation Method 3
The periodic secondary air enables generation of a cycle of the lean state and the non-lean state. The catalyst affixed to the filter can maintain a high temperature and promote the combustion function because the periodic secondary air enables generation of a cycle of the adsorption heat and the oxidation heat
Data Source
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AI summary
An exhaust purification device includes: a filter 33 including an OSC material; a secondary air supply passage 40 connected to the exhaust passage 30 upstream of the filter; a secondary air control valve 42 disposed in the secondary air supply passage and configured to provide periodicity to the secondary air supplied to the secondary air supply passage; and an ECU 100, wherein the ECU controls the secondary air control valve so as to supply secondary air with a predetermined frequency and a maximum amplitude of an oxygen concentration, and wherein the secondary air control valve is controlled so that when the frequency of the secondary air is fixed to a value of more than 0Hz and 1.5Hz or less, the maximum amplitude of the oxygen concentration is more than 0.50% and 3.0% or less.