Pressure-Based Soot Sensor for Diesel Exhaust
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing soot sensors face issues with non-uniform soot deposit due to biased flow distribution, difficulty in reaching regeneration temperature due to large flow impingement, and contamination from particulates and water droplets, leading to inaccurate readings and regeneration challenges.
Innovation Solution
A pressure-based soot sensor is positioned downstream of a particulate filter, where soot particles accumulate to increase pressure, acting on a piston to indicate soot levels, reducing the impact of biased flow and contamination, and using this pressure correlation alongside conductivity to enhance accuracy and sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a soot sensor collects particles on charged electrodes with voltage supply and current sensing, then soot detection is enabled, but non-uniform soot deposit occurs due to biased flow distribution resulting in inaccurate readings
Solution Approach 1:
Instead of measuring soot through electrical conductivity across electrodes (voltage/current method), the patent inverts the approach by measuring pressure differential across the sensor surface. The pressure differential is directly proportional to soot mass accumulated, eliminating the need for uniform electrical deposit and providing accurate soot measurement regardless of flow distribution patterns.
Solution Approach 2:
The patent replaces the electrical measurement system (voltage/current sensing across electrodes) with a mechanical measurement system (pressure differential sensing). This substitution eliminates the dependency on uniform electrical conductivity distribution and provides a direct measure of total soot mass accumulated on the sensor surface.
2Quantity of substance
If exhaust flow impinges on the sensor surface, then soot particles are collected, but it becomes difficult to reach sensor regeneration temperature
Solution Approach 1:
The patent extracts the soot collection function from the exhaust flow path by positioning the sensor surface perpendicular to the flow direction. This allows soot particles to be collected on the sensor surface while minimizing the cooling effect of continuous exhaust flow impingement, thereby enabling easier achievement of regeneration temperature.
Solution Approach 2:
The patent changes the orientation of the sensor surface from parallel to perpendicular relative to the exhaust flow direction. This dimensional change in orientation reduces the surface area exposed to direct flow impingement, minimizing cooling effects while maintaining soot collection capability through pressure differential measurement.
3Quantity of substance
If exhaust flow impinges on the sensor surface, then soot particles are collected, but contamination from particulates and water droplets occurs
Solution Approach 1:
The patent extracts the soot collection function from direct exhaust flow contact by using a pressure differential measurement approach. The sensor surface is positioned perpendicular to the flow, allowing soot particles to be collected and measured through pressure changes rather than direct impingement, thereby reducing contamination from particulates and water droplets.
Solution Approach 2:
The patent introduces pressure differential as an intermediary measurement parameter between the exhaust flow and the sensor. Instead of directly measuring soot through electrical conductivity affected by contamination, the pressure differential serves as an intermediary that reflects soot mass accumulation while being less sensitive to contamination from particulates and water droplets.
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 approach improves the accuracy and sensitivity of soot detection and regeneration control, reducing the sensor's sensitivity to aberrant soot distribution and enabling more effective monitoring of diesel particulate filter degradation.
Implementation Method 1
collecting soot particles on a sensor surface downstream of a particulate filter to increase pressure inside the sensor
Implementation Method 2
a piston within the housing, affixed to a spring via a conductive surface, with the spring fluidly separated from the exhaust chamber by a piston seal. The accumulation of soot in the soot sensor filter decreases the filter flow permeability, increasing the pressure inside the sensor chamber. With an increase of pressure, the piston inside the inner tube rises
Implementation Method 3
a separate regeneration circuit configured to supply electric heat to burn off, or incinerate, soot particles in the soot sensor filter
Implementation Method 4
a piston within the housing, affixed to a spring via a conductive surface
Data Source
AI summary
Systems and methods are described for sensing soot (particulate matter) in an exhaust system of a vehicle. An example system comprises a sensor housing an exhaust inlet, an exhaust outlet, and a soot filter affixed across the exhaust outlet, and a piston with the housing, affixed to a spring via a conductive surface, the spring fluidly separated from the exhaust chamber by a piston seal. The system may further comprise a detection circuit including the conductive surface of a piston and a plurality of resistive elements and a separate regeneration circuit configured to supply electric heat across the soot filter to regenerate the sensor.