Injector Mounting Assembly Thermal Isolation Gasket
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Solution Overview
Problem
Engine exhaust after-treatment systems face challenges in maintaining the effectiveness of reductant injectors due to high exhaust gas temperatures, which can impair the efficacy of selective catalytic reduction (SCR) processes and damage the injectors themselves.
Innovation Solution
A mounting assembly for reductant injectors is designed with a gasket and insulation to thermally isolate the injector from the exhaust line, including a gasket with a nozzle aperture and a thermal insulation layer, and a shim layer to provide sealing and thermal protection, ensuring the injector operates within safe temperature limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the injector is mounted directly to the exhaust line, then the installation is simple and direct, but the injector is exposed to high temperatures that can reach more than 500°C, which adversely impacts the efficacy of the reductant and can harm the injector itself
Solution Approach 1:
A thermal barrier layer is introduced as an intermediary between the exhaust line and the injector mounting flange. This layer physically separates the injector from the high-temperature exhaust environment while maintaining the mounting connection, thereby reducing thermal exposure to the injector without complicating the overall assembly structure
Solution Approach 2:
The mounting assembly utilizes composite construction with a thermal barrier layer made of heat-resistant material positioned between the exhaust line and the injector flange. This composite structure combines materials with different thermal properties to protect the injector from high temperatures while maintaining structural integrity and simplicity
2Reliability
If a thermal barrier layer is added between the exhaust line and the injector, then the injector is protected from high temperatures, but the mounting assembly complexity increases
Solution Approach 1:
The mounting flange assembly is designed to serve multiple functions simultaneously: it provides mechanical mounting attachment between the exhaust line and injector, and incorporates the thermal barrier layer to provide thermal protection. This multi-functionality reduces the need for separate protective components, thereby maintaining simplicity while improving reliability
Solution Approach 2:
The thermal barrier layer is integrated into the mounting flange assembly rather than being a separate component. The mounting flange and thermal barrier are combined into a single integrated structure that performs both mounting and thermal protection functions, reducing the number of parts and assembly complexity while ensuring reliable thermal protection
3Productivity
If the reductant is exposed to high temperatures in the exhaust stream, then the SCR process can proceed, but the efficacy of the reductant is adversely impacted and chemical changes can occur
Solution Approach 1:
The thermal barrier layer is positioned upstream of the injector nozzle, creating a protected zone before the reductant is introduced into the exhaust stream. This preliminary thermal protection ensures that the reductant remains at appropriate temperatures for effective SCR operation, preventing premature thermal degradation before the chemical reaction begins
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
The solution effectively protects the reductant injector from high temperatures, maintaining its performance and extending its lifespan by preventing overheating and ensuring efficient operation of the SCR process.
Implementation Method 1
The gasket is interposed between the distal mounting surface of each of the plurality of mounting feet and the corresponding distal mounting face of the plurality of mounting bosses of the exhaust line
Implementation Method 2
the gasket is interposed between, and in sealing engagement with, the sealing surface of the exhaust line and the sealing plate of the injector
Data Source
AI summary
A mounting assembly for an injector is located in a curved portion of an exhaust line having an exhaust flow from an upstream end to a downstream end. The mounting assembly includes an indent extending at least partially into the exhaust line curved portion and disposed in the exhaust flow. The downstream wall has an interior surface oriented to substantially face the exhaust line downstream end. A recess extends from the downstream wall in a direction away from the exhaust line downstream end, and a recess aperture is formed in the recess and configured to fluidly communicate with the injector. The recess reduces the amount of exhaust heat reaching the injector tip.