Exhaust System Single Oxygen Sensor Catalyst Design
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Solution Overview
Problem
Conventional exhaust systems for internal combustion engines face challenges in enhancing catalyst purification efficiency while maintaining low manufacturing costs, particularly due to the need for multiple oxygen sensors and increased catalyst devices with the number of cylinders, leading to higher costs and potential pressure interference issues.
Innovation Solution
An exhaust system design where a single oxygen detector controls fuel injection across multiple cylinders, with non-communicating inflow portions to prevent interference, and a shared catalyst device reduces the number of catalysts and sensors needed, optimizing air-fuel ratios for improved purification efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a catalyst device is provided in each exhaust pipe of multiple cylinders, then purification efficiency is improved, but manufacturing cost increases due to increased number of catalyst devices
Solution Approach 1:
The patent merges multiple exhaust pipes into a single exhaust pipe that connects to one catalyst device. Specifically, exhaust pipes from multiple cylinders are combined into one common exhaust passage, allowing a single catalyst device to treat exhaust gas from all cylinders, thereby reducing the total number of catalyst devices needed while maintaining purification efficiency
Solution Approach 2:
The single catalyst device is designed to handle exhaust gas from multiple cylinders simultaneously, making it a multi-functional component that serves the purification needs of all cylinders rather than requiring dedicated catalysts for each cylinder
2Measurement precision
If oxygen sensors are provided in each inflow portion to detect exhaust gas components accurately, then measurement precision is improved, but manufacturing cost increases due to increased number of sensors
Solution Approach 1:
The patent combines multiple oxygen sensor installations into a single sensor location. Instead of placing oxygen sensors in each individual inflow portion or exhaust pipe, the design uses one oxygen sensor in the common exhaust passage to detect the overall exhaust gas composition, thereby reducing sensor quantity while maintaining adequate detection capability
Solution Approach 2:
The single oxygen sensor serves the function of monitoring exhaust gas composition for all cylinders simultaneously, making it a multi-functional detection component that replaces what would otherwise require multiple separate sensors
3Device complexity
If exhaust pipes of multiple cylinders are merged into one chamber, then device complexity is reduced, but pressure interference occurs between exhaust gases
Solution Approach 1:
The patent segments the common exhaust passage into multiple independent flow paths using partition walls. These partitions create separate channels within the unified exhaust structure, allowing exhaust gases from different cylinders to flow independently without interfering with each other's pressure, while still converging to a single catalyst device
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 design enhances catalyst purification efficiency by reducing the need for multiple detectors and catalysts, minimizing manufacturing costs and preventing pressure interference, allowing for efficient catalyst activation and reduced engine output losses.
Implementation Method 1
a catalyst device having a catalyst that cleanses the gas introduced through the plurality of first exhaust pipes
Implementation Method 2
a first detector provided in any one of the plurality of first exhaust pipes or any one of the plurality of first inflow portions and arranged to detect the information about oxygen concentration of the gas exhausted from a respective one of the plurality of cylinders
Data Source
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AI summary
In an exhaust system, a first oxygen sensor (S1) is attached to an exhaust pipe (101) connected to a standard cylinder in which the amount of injected fuel is the closest to the average of the amounts of fuel injected in a plurality of cylinders. A controller calculates the air-fuel ratio of the standard cylinder based on the value detected by the first oxygen sensor (S1). Then, based on the difference between the calculated air-fuel ratio of the standard cylinder and a predetermined target air-fuel ratio, the amount of correction to the amount of fuel injected in the standard cylinder is determined such that the air-fuel ratio of the standard cylinder is equal to the target air-fuel ratio. Furthermore, based on the amount of correction to the amount of fuel injected in the standard cylinder, the amounts of correction of the other cylinders are determined.