Injection Device Nozzle Collar Welding for Thermal Mass Reduction
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Solution Overview
Problem
The production of injection devices for introducing reducing agents into exhaust gas streams is complex due to the geometric challenges of connecting round cross-section components, leading to high thermal mass and potential damage to sensitive injectors, and existing solutions either require complex manufacturing processes or increase the number of parts, thereby increasing costs.
Innovation Solution
The injection device features a laterally projecting collar around the socket's inner end that is welded to the exhaust pipe, reducing the thermal mass and requiring only a single welded connection, while a two-shell exhaust pipe design allows for easier assembly and integration of a static mixer to enhance evaporation and mixing of the reducing agent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large flange is used at the inner end of the socket to enable welding to the exhaust pipe, then the connection stability is improved, but the thermal mass of the socket increases, leading to heat absorption and potential damage to the injector
Solution Approach 1:
The socket is divided into two functional parts: a thin-walled main body for low thermal mass and a separate collar for structural support and welding. This segmentation allows the connection function to be separated from the thermal mass, enabling stable welding without excessive heat absorption.
Solution Approach 2:
The collar acts as an intermediary element between the socket and the exhaust pipe. It provides the necessary structural support and welding surface while being thermally isolated from the injector by the thin-walled socket body, thus mediating between the need for stable connection and the need to protect the injector from heat.
2Ease of operation
If the connecting piece is connected at an angle relative to the perpendicular direction, then the geometric transition is improved for better flow, but the manufacturing complexity increases due to the complex geometric transition between round cross-section components
Solution Approach 1:
The socket and connecting piece both feature round cross-sections with curved transitions. The inclined connection is achieved through smooth geometric transitions that maintain rotational symmetry, avoiding sharp edges and complex angular joints that would be difficult to manufacture.
Solution Approach 2:
The socket is designed as a universal component that can be connected to the exhaust pipe at various angles while maintaining its round cross-section. This multi-functional design allows the same basic geometry to serve both flow optimization and manufacturing simplicity requirements.
3Ease of manufacture
If a separate adapter is used to connect the socket to the exhaust pipe, then the manufacturing of the socket can be simplified with reduced wall thickness, but the device complexity increases due to the increased number of parts and work steps
Solution Approach 1:
The collar is merged with the socket to form a single integrated component. This combining eliminates the need for separate adapters while maintaining the simplified thin-walled socket design, as the collar is formed as part of the socket manufacturing process itself.
Solution Approach 2:
The collar is pre-formed as an integral part of the socket during socket manufacturing. This preliminary action incorporates the welding support structure into the socket itself before assembly, eliminating the need for separate adapter components and reducing the number of assembly steps.
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 simplifies the production process, reduces thermal stress on the injector, and enhances the efficiency of reducing agent evaporation and mixing, resulting in a cost-effective and stable connection within the exhaust system.
Implementation Method 1
The reducing agent evaporates in the exhaust gas flow
Implementation Method 2
can react to form ammonia and carbon dioxide through thermolysis and subsequent hydrolysis
Implementation Method 3
the collar is then welded to the wall
Implementation Method 4
enhances the efficiency of reducing agent evaporation and mixing
Data Source
Figure 1~2
Figure 3
AI summary
The present invention relates to an injection device (14) for introducing a reducing agent (11) into an exhaust gas stream (8) of an exhaust system (7) of an internal combustion engine (1), comprising an exhaust pipe (15) for guiding the exhaust gas stream (8), which has a nozzle opening (18) in a wall (17) and a nozzle (16) which is inserted into the nozzle opening (18) at an inner end (19) and is provided at an outer end (20) for connecting an injector (10). Simplified assembly is achieved if the nozzle (16) has a laterally projecting, fully circumferential collar (22) at its inner end (19), which rests against an opening edge (24) surrounding the nozzle opening (18) on an inner side (23) of the wall (17) and is welded to the wall (17).