Particle Sensor Flow Element for Reproducible Soot Detection
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Solution Overview
Problem
Existing particle detection sensors in fluids, particularly in exhaust gases, face challenges in reliably and reproducibly accumulating particles under varying operating conditions due to issues with particle deposition and protection against water hammer and aggressive particles.
Innovation Solution
A sensor with an electrically insulating ceramic substrate and an interdigital electrode arrangement, protected by a flow element designed to maintain consistent flow conditions and deflect larger particles, ensuring reproducible particle accumulation and accurate measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If particles are captured and deposited on the substrate in existing sensors, then particle detection is achieved, but reproducible accumulation under different operating states cannot be ensured
Solution Approach 1:
The patent changes the flow conditions parameter by designing a specific inflow element that creates reproducible stagnation point flow or laminar flow patterns. This ensures consistent flow velocity and direction across different operating states, enabling reliable particle accumulation on the electrode arrangement regardless of varying external conditions.
Solution Approach 2:
The inflow element acts as an intermediary component between the fluid stream and the electrode arrangement. It mediates the flow conditions by deflecting the fluid and particles in a controlled manner, ensuring that only particles following diffusion laws reach the electrodes while larger particles are redirected, thus improving measurement reliability.
2Productivity
If the electrode arrangement is exposed to the fluid stream, then particle capture is enabled, but protection against water hammer and larger aggressive particles is lost
Solution Approach 1:
The inflow element serves as a protective intermediary between the harsh fluid environment and the sensitive electrode arrangement. It deflects water hammer impacts and redirects larger aggressive particles away from the electrodes, while still allowing smaller detectable particles to reach the sensing surface through controlled flow paths.
Solution Approach 2:
The patent applies different flow deflection characteristics to different regions of the inflow element. The design creates zones with specific flow properties that selectively guide different particle sizes - smaller particles follow the flow toward electrodes while larger particles are redirected away, providing localized protection where needed.
3Adaptability or versatility
If changes in direction occur between fluid flow and particle transport, then flow adaptation is achieved, but reproducible flow conditions and clear functional relationship to exhaust gas speed are compromised
Solution Approach 1:
The inflow element design creates equipotential flow conditions by ensuring that the flow velocity and direction at the electrode arrangement directly reflect the external exhaust gas speed without introducing additional directional changes. This maintains a clear functional relationship between external flow conditions and particle transport to the sensors.
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 enables reliable and reproducible particle accumulation, improving the accuracy and functionality of the sensor across different operating states by maintaining consistent flow conditions and deflecting undesirable particles.
Implementation Method 1
a sensor (10) for detecting particles in a fluid has an inflow element (30), has an electrically well insulating substrate material, in particular a ceramic material, with the electrode arrangement (12) being provided on the substrate material or in the substrate material
Data Source
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Figure 3
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AI summary
A sensor for detecting particles in a fluid and a method for detecting particles in a fluid, in particular soot particles of a combustion operation in a motor vehicle engine, are proposed, wherein the sensor has an electrode arrangement and an inflow element, wherein the electrode arrangement has a plurality of electrode partial sections and wherein the electrode partial sections essentially extend in an elongate manner in a respective main direction of extent, wherein the inflow element also has flow-guiding means for guiding the local flow of fluid in such a manner that the local flow of fluid is essentially provided for each of the electrode partial sections in a manner essentially parallel to the respective main direction of extent of the latter.