Sensor Shield Wake Area for Exhaust Gas Mixing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In exhaust treatment systems of work vehicles, NOx sensors often underestimate or overestimate NOx concentrations due to incomplete mixing of exhaust gases from separate catalyst lines, leading to excessive reductant injection, clogging, increased backpressure, and potential sensor damage from liquid droplets.
Innovation Solution
A sensor shield with a hub and flow divider beams is positioned upstream of the NOx sensor to create a wake area, generating turbulent exhaust flow that mixes and accelerates the gases, ensuring more accurate emissions readings and reducing liquid droplet impact on the sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If exhaust gases from separate catalyst lines are combined upstream of the NOx sensor, then the sensor can monitor emissions, but the gases are not fully mixed causing inaccurate NOx concentration readings
Solution Approach 1:
A sensor shield with wake area is introduced as an intermediary element between the exhaust gas flow and the NOx sensor. The shield creates a wake region that acts as a mixing zone, allowing turbulent eddies to form and enhance gas mixing before the exhaust reaches the sensor, thereby improving measurement accuracy without requiring additional mixing devices
Solution Approach 2:
The sensor shield modifies the flow parameters (velocity, turbulence intensity) by creating a wake area with altered flow characteristics. This change in flow parameters promotes better mixing of exhaust gases from different catalyst lines, ensuring more representative sampling at the sensor location
2Reliability
If the NOx sensor is positioned to monitor exhaust flow, then emissions can be controlled, but liquid droplets in the exhaust gas can impinge on and damage the sensor
Solution Approach 1:
The sensor shield serves as a protective intermediary between the harsh exhaust environment (containing liquid droplets) and the sensitive NOx sensor. The shield's structure intercepts and redirects liquid droplets away from the sensor while allowing gas phase exhaust to pass through the wake area to the sensor
Solution Approach 2:
The sensor shield performs preliminary separation of liquid droplets from the exhaust flow before the gas reaches the sensor. By creating a wake area that promotes droplet coalescence and redirection, the shield prepares the exhaust flow in advance, removing harmful liquid particles before sensor exposure
3Quantity of substance
If reductant is injected based on sensor readings, then NOx emissions can be reduced, but inaccurate readings lead to excessive reductant injection causing clogging and ammonia slip
Solution Approach 1:
The sensor shield improves the feedback signal quality by ensuring accurate NOx concentration measurements through better gas mixing. This enhanced feedback allows the control system to make more precise reductant injection decisions, avoiding both excessive injection (which causes clogging and ammonia slip) and insufficient injection (which fails to reduce emissions)
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 sensor shield enhances the accuracy of NOx readings, preventing excessive reductant injection and ammonia slip, while minimizing sensor damage from liquid droplets, thus improving the overall efficiency and reliability of the exhaust treatment system.
Implementation Method 1
the sensor shield creates a wake area downstream of the hub within which a turbulent exhaust flow is generated as the treated exhaust is directed past the sensor shield
Data Source
AI summary
A sensor assembly for use within a flow conduit, the flow conduit configured to receive a treated exhaust of an exhaust treatment system of a work vehicle, includes an exhaust sensor positioned within the flow conduit between the upstream and downstream ends. Moreover, the exhaust sensor is configured to detect an amount of an emission gas present in the treated exhaust. The sensor assembly further includes a sensor shield positioned within the flow conduit upstream of the exhaust sensor. The sensor shield includes a hub and a plurality of flow divider beams extending from the hub. Additionally, the sensor shield creates a wake area downstream of the hub within which a turbulent exhaust flow is generated as the treated exhaust is directed past the sensor shield. Furthermore, the exhaust sensor is configured to receive the turbulent exhaust flow from the wake area.