Optical Particle Sensor Fluidic Shielding
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Solution Overview
Problem
Particle sensors used for detecting soot particles in exhaust gases face contamination issues over their service life, leading to reduced transparency of optical access for laser light and thermal radiation, which impairs their functionality.
Innovation Solution
A sub-flow from the measuring gas is diverted and fluidically shielded to prevent contaminants from reaching the optical access, ensuring continued transparency and extending the sensor's service life by redirecting the sub-flow away from the optical access using constructive measures such as swirl flaps and tapered tubes within the sensor's housing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the optical access is exposed to the measuring gas flow, then the sensor can detect particles in the exhaust gas, but the optical access becomes contaminated over time
Solution Approach 1:
The exhaust gas flow is segmented into a main flow that passes through the optical access for particle detection and a sub-flow that is diverted away from the optical access. This segmentation allows the sensor to maintain detection capability while preventing contamination of the optical access components.
Solution Approach 2:
A sub-flow of exhaust gas is introduced as an intermediary element that carries particles away from the optical access. This sub-flow acts as a mediator that protects the optical access from direct contact with contaminants while still allowing the main flow to provide the necessary particles for detection.
2Object-affected harmful factors
If the optical access is shielded from the measuring gas flow, then contamination is prevented, but particle detection capability is reduced
Solution Approach 1:
The exhaust gas flow is divided into a main flow that provides particles for detection and a sub-flow that is redirected away from the optical access. This segmentation enables the system to maintain both detection capability and protection from contamination simultaneously.
Solution Approach 2:
Different regions of the exhaust gas flow are given different qualities: the main flow maintains particle concentration for detection, while the sub-flow is redirected to a different path that avoids the optical access. This local differentiation allows simultaneous achievement of detection and protection.
3Measurement precision
If a sub-flow is removed from the measuring gas flow and supplied to the laser focus, then particle detection is enhanced, but the optical access may be contaminated
Solution Approach 1:
A sub-flow of exhaust gas is introduced as an intermediary that delivers particles to the laser focus for enhanced detection. This sub-flow acts as a mediator that provides the necessary particles for accurate measurement while being managed separately to prevent contamination of the optical access.
Solution Approach 2:
The exhaust gas flow is segmented into a main flow and a sub-flow. The sub-flow is specifically directed to the laser focus to enhance particle detection, while the main flow continues to provide particles for detection without compromising optical access transparency.
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 effectively prevents contamination of the optical access, maintaining the sensor's functionality and extending its service life by ensuring the optical access remains clear for laser light and thermal radiation detection.
Implementation Method 1
The sensor described in German Patent Application No. DE 10 2017 207 402 A1 describes the measuring principle of laser-induced incandescence.
Implementation Method 2
The detector is situated in the soot particle sensor in such a way that it detects radiation emanating from the spot.
Data Source
AI summary
A particle sensor for detecting particles in a flow of a measuring gas for detecting soot particles in an exhaust gas channel of a burner or of an internal combustion engine. The particle sensor includes a device for generating or for supplying laser light, a device for focusing laser light, and a device for detecting or transferring thermal radiation. The particle sensor includes at least one optical access, which separates an area exposed to the measuring gas from an area facing away from the measuring gas not exposed to the measuring gas, the device for generating or supplying laser light and/or the device for detecting or for transferring thermal radiation being situated in the area facing away from the measuring gas, wherein the particle sensor removes a sub-flow from the measuring gas flow and supplies it to the laser focus and further fluidically shields the optical access from the sub-flow.