Secondary Air Supply System for Vehicle Exhaust Purification
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Solution Overview
Problem
Existing secondary air supply systems for vehicles face challenges in efficiently purifying exhaust gases due to the trade-off between secondary air oxidation and catalyst device efficiency, where increased secondary air supply reduces catalyst efficiency and decreases unburned component removal.
Innovation Solution
A secondary air supply system with first and second paths that are selectively switched based on engine state, determined by a determiner, to adjust secondary air supply to optimize oxidation reactions and catalyst efficiency, ensuring efficient removal of unburned components and nitrogen oxides.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If secondary air is supplied to the exhaust passage to promote oxidation of unburned components, then unburned components (HC and CO) are removed efficiently, but the efficiency of purifying nitrogen oxide (NOx) by the catalyst device is reduced
Solution Approach 1:
The patent applies dynamics by making the secondary air supply system adjustable based on engine operating conditions. The control unit dynamically opens or closes the secondary air supply passage according to detected engine state (e.g., idle, acceleration, high-speed cruise), allowing the system to adapt between promoting oxidation and maintaining catalyst efficiency for NOx purification under different conditions.
Solution Approach 2:
The patent changes the parameter of secondary air supply amount based on engine state. By controlling the opening/closing of the secondary air supply passage, the system varies the air-fuel ratio in the exhaust passage to optimize for different purification needs - leaner mixture for HC/CO oxidation during idle, and richer mixture for NOx purification during high-speed operation.
2Productivity
If secondary air is supplied to increase the air-fuel ratio in the exhaust passage for oxidation, then unburned components are removed, but the amount of oxygen flowing into the catalyst device increases, reducing catalyst efficiency
Solution Approach 1:
The system dynamically adjusts the secondary air supply based on real-time engine state detection. During idle conditions, the secondary air passage is opened to promote oxidation of unburned components. During high-speed or high-load conditions, the passage is closed to maintain optimal oxygen levels for catalyst efficiency, thus dynamically balancing the two competing requirements.
Solution Approach 2:
The control unit receives feedback from the engine state detection unit (which monitors parameters like engine speed, load, and temperature) and adjusts the secondary air supply accordingly. This feedback mechanism ensures that the system always operates in the optimal mode for the current conditions, preventing sustained high oxygen levels that would harm catalyst performance.
3Productivity
If multiple paths for secondary air supply are provided to optimize purification based on engine state, then exhaust gas treatment efficiency is improved, but the device complexity increases
Solution Approach 1:
The patent segments the secondary air supply system into multiple independent paths (first secondary air supply passage and second secondary air supply passage), each that can be independently controlled. This allows selective activation of different paths based on engine state, providing flexible control over the total secondary air supply amount without requiring a completely complex control system.
Solution Approach 2:
The control unit serves multiple functions: it detects engine state, determines optimal purification mode, controls the secondary air supply passage, and monitors catalyst performance. This multi-functionality reduces the need for separate dedicated components for each function, thereby limiting the increase in overall device complexity while achieving sophisticated control.
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 system effectively improves exhaust gas purification by adjusting secondary air supply based on engine state, balancing oxidation reactions and catalyst efficiency to enhance overall exhaust gas treatment.
Implementation Method 1
This promotes oxidation reaction of unburned components included in the exhaust gas of the engine. As a result, the unburned components included in the exhaust gas are removed.
Implementation Method 2
a catalyst device that is provided in the exhaust passage and purifies the exhaust gas exhausted from the engine
Data Source
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AI summary
A secondary air supply system includes a CPU, a first air supply pipe, a second air supply pipe, a first shut-off valve and a second shut-off valve. One ends of the first air supply pipe and the second air supply pipe are connected to an air cleaner box and the other ends thereof are connected to an exhaust port. The CPU controls opening/closing of the first shut-off valve and the second shut-off valve based on a state of an engine. The first shut-off valve and the second shut-off valve are selectively opened by the CPU, so that air in the air cleaner box is supplied to the exhaust port through the first air supply pipe or the second air supply pipe.