Exhaust Manifold Flow Regulating Path for Catalyst Warm-Up
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Solution Overview
Problem
Existing exhaust gas purifying devices for internal combustion engines face challenges in maintaining high purification performance while minimizing the use of noble metals due to heat degradation and slow temperature rise in catalytic converters.
Innovation Solution
The device includes a catalytic converter positioned downstream of the exhaust manifold with a flow regulating path that narrows in width, enhancing heat resistance and purification efficiency by ensuring high-temperature exhaust gas efficiently reaches the catalysts, and utilizing layered catalyst structures with Pd, Rh, and Pt supported on oxygen storage materials to suppress degradation and improve NOx, NMOG, HC, and CO purification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the catalytic converter is provided directly below the engine to supply high temperature exhaust gas, then the warm-up time is shortened, but the catalyst degradation due to heat becomes intense requiring more noble metal
Solution Approach 1:
The catalytic converter is divided into two distinct catalysts: an upstream catalyst positioned to receive high-temperature exhaust gas for rapid warm-up, and a downstream catalyst positioned to receive moderately heated exhaust gas for sustained purification. This segmentation allows each catalyst to operate in its optimal temperature range, reducing overall noble metal requirements while maintaining reliability.
Solution Approach 2:
Different regions of the exhaust system are assigned different functions: the upstream catalyst zone is optimized for rapid heating with high-temperature exhaust, while the downstream catalyst zone is optimized for purification with moderate-temperature exhaust. This local differentiation of quality allows the system to achieve both fast warm-up and long-term reliability without excessive noble metal usage.
2Reliability
If a second catalytic converter is provided separated from the first to reduce heat degradation, then catalyst reliability improves, but the time required for temperature rise increases
Solution Approach 1:
The upstream catalyst is positioned to receive high-temperature exhaust gas first, performing preliminary heating and initial purification functions. This preliminary action ensures that the exhaust gas is sufficiently heated before reaching the downstream catalyst, enabling the downstream catalyst to reach operational temperature faster while still benefiting from reduced heat degradation.
3Productivity
If the flow regulating path has a narrow width to suppress exhaust gas circling, then purification efficiency improves, but the amount of noble metal required increases
Solution Approach 1:
The purification function is segmented between two catalysts with different noble metal compositions and functions. The upstream catalyst uses a noble metal formulation optimized for high-temperature operation and rapid warm-up, while the downstream catalyst uses a different formulation optimized for moderate-temperature purification. This segmentation allows each catalyst to use less noble metal overall while maintaining high purification efficiency.
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 configuration maintains sufficient exhaust gas purification performance while reducing the amount of noble metal used, improves air/fuel ratio detection sensitivity, and extends catalyst lifespan by suppressing heat-induced degradation and oxidation.
Implementation Method 1
a flow regulating path of a predetermined length that rectifies the exhaust gas and has a width that gradually narrows to a downstream side
Implementation Method 2
the upstream catalyst has a carrier, an upstream first layer disposed on the carrier and containing Pd, an upstream second layer disposed on the upstream first layer and containing Rh, and an upstream third layer disposed on the upstream second layer and containing Pd
Implementation Method 3
utilizing layered catalyst structures with Pd, Rh, and Pt supported on oxygen storage materials to suppress degradation and improve NOx, NMOG, HC, and CO purification
Data Source
AI summary
An exhaust gas purifying device is provided with an exhaust manifold having a collecting section, and a catalytic converter provided downstream of the exhaust manifold. The catalytic converter has upstream and downstream catalysts. The upstream catalyst includes a carrier, a first layer located on the carrier containing Pd, a second layer located on the first layer containing Rh, and a third layer located on the second layer containing Pd. The downstream catalyst includes a carrier, a first layer located on the carrier containing Pd, and a second layer located on the first layer containing Pt and Rh. The collecting section connects to the catalytic converter after passing, in order from the upstream side, through a flow regulating path and a neck section which is provided in the flow regulating path. The flow regulating path has a predetermined length and a width which is gradually reduced to the downstream side.