Helical Dosing Lance Mitigates Thermal Stress in Exhaust Systems
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Solution Overview
Problem
In aftertreatment systems for internal combustion engines, thermal gradients between components of the dosing lance assembly lead to the accumulation of thermal stresses, compromising the structural integrity, particularly in high-horsepower applications.
Innovation Solution
A dosing lance assembly with a helical delivery conduit that expands and contracts with temperature changes, mitigating stress accumulation by maintaining a length greater than the attachment distance, allowing for thermal deformation and reducing stress at junctures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a rigid pipe is used to deliver reductant through the housing, then the delivery path is straightforward and easy to manufacture, but thermal stresses accumulate at junctures due to temperature gradients, leading to potential failure
Solution Approach 1:
The pipe is changed from a rigid structure to a flexible hose, fundamentally altering its mechanical parameters. This flexibility allows the hose to accommodate thermal expansion and contraction without accumulating stress at junctures, thereby maintaining reliability while remaining manufacturable through standard flexible conduit installation practices
Solution Approach 2:
A flexible hose is used instead of a rigid pipe to deliver reductant. The flexible nature of the hose allows it to deform elastically in response to thermal gradients, preventing stress accumulation at connection points between the housing and the delivery conduit, thus resolving the contradiction between ease of manufacture and reliability
2Stability of the object's composition
If the pipe is maintained at reductant temperature while the housing is heated by exhaust, then reductant delivery is stable, but a temperature gradient is created that causes stress accumulation at junctures
Solution Approach 1:
The flexible hose can accommodate thermal gradients by deforming its shape and length in response to differential heating. The hose maintains its functional stability for reductant delivery while its flexibility allows it to absorb thermal stress without transmitting it to connection points, resolving the contradiction between temperature stability and stress accumulation
Solution Approach 2:
Changing from a rigid pipe to a flexible hose alters the thermal-mechanical response of the delivery conduit. The hose can dynamically adjust its physical parameters (length, curvature) in response to temperature changes, maintaining stable reductant flow while preventing stress buildup at junctures
3Productivity
If a straight conduit is used, then the path length is minimized for efficient reductant delivery, but thermal deformation is restricted leading to stress accumulation
Solution Approach 1:
The flexible hose provides a compromise between straight-line efficiency and thermal accommodation. It can be routed to maintain relatively short delivery paths while its flexibility allows it to deform locally to accommodate thermal expansion and contraction, preventing stress accumulation without significantly increasing the overall delivery path length
Solution Approach 2:
The flexible hose naturally adopts curved configurations rather than straight lines. These curves provide the necessary compliance to accommodate thermal deformation while maintaining efficient reductant delivery. The curved path allows for stress distribution along the hose length rather than concentration at specific junctures
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 helical design effectively mitigates thermal stress accumulation, enhancing the structural integrity and longevity of the dosing lance assembly by accommodating temperature fluctuations, thereby reducing the risk of failure and maintaining system performance across multiple cycles.
Implementation Method 1
the temperature of the housing increases while the temperature of the pipe is substantially maintained at the temperature of the reductant. As a result, a temperature gradient is created at junctures between the pipe and the housing. Stresses accumulate at the junctures due to the temperature gradient
Data Source
AI summary
A dosing lance assembly for an exhaust component includes: a housing comprising: a plate having a first channel, an endcap having a second channel, and a pipe having a first end coupled to the plate and a second end coupled to the endcap, wherein at least a portion of the pipe is airfoil-shaped; and a delivery conduit having a first end coupled to the plate and a second end coupled to the endcap, such that reductant is flowable from the first channel to the second channel.