Textured Shroud Tortuous Path for Ultrasonic Sensor Aeration
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Solution Overview
Problem
Air bubbles in fluid systems, such as Diesel Exhaust Fluid (DEF) in SCR systems, interfere with ultrasonic sound wave measurements, leading to inaccurate fluid level and concentration sensing due to dispersion of sound waves, which affects the efficiency of NOx reduction and system operation.
Innovation Solution
A textured shroud is used to separate the liquid and gas portions of the fluid, allowing the liquid to enter the sensing area while prohibiting gas bubbles, ensuring accurate measurements by directing the gas portion away from the sensing area through a tortuous path and venting system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a standard sensor is used to sense fluid characteristics, then the sensor can detect fluid level and concentration, but air bubbles disperse ultrasonic sound waves causing measurement inaccuracies
Solution Approach 1:
A shroud structure is introduced as an intermediary component between the ultrasonic sensor and the fluid. The shroud includes a tortuous path channel that forces gas bubbles to take a longer, more complex path while liquid follows a more direct path, effectively separating the two phases and preventing bubbles from reaching the sensor where they would interfere with measurements
Solution Approach 2:
The sensing system is segmented into distinct functional zones: a tortuous path section for gas separation, a straight path section for liquid flow, and a protected sensing area. This segmentation allows different fluid phases to be handled differently, with gas being diverted away from the sensor while liquid maintains direct access for accurate measurement
2Reliability
If the sensing area is directly exposed to fluid flow, then fluid can be sensed accurately, but gas bubbles can enter and interfere with measurements
Solution Approach 1:
The tortuous path channel performs preliminary separation of gas and liquid phases before they reach the sensing area. By forcing gas bubbles to traverse a longer, more complex path earlier in the fluid flow, the system prepares the fluid stream in advance, ensuring that bubbles are diverted away from the sensor before measurement occurs
Solution Approach 2:
The tortuous path incorporates curved and angled sections that exploit the spherical shape and buoyancy of gas bubbles. The curved paths cause bubbles to naturally rise and follow the tortuous route, while the straighter liquid path allows denser liquid to flow directly to the sensor, utilizing geometric design to achieve phase separation
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 effectively prevents gas bubbles from interfering with ultrasonic measurements, enabling accurate fluid level and concentration sensing, thereby maintaining the efficiency of the SCR system and preventing damage from contaminated DEF.
Implementation Method 1
A textured shroud is used to separate the liquid and gas portions of the fluid, allowing the liquid to enter the sensing area while prohibiting gas bubbles, ensuring accurate measurements by directing the gas portion away from the sensing area through a tortuous path and venting system
Implementation Method 2
The transducer outputs a pulse of sound through the liquid portion of the fluid contained within the sensing area, receives the reflected pulse of sound, and outputs a characteristic of the fluid based on the received pulse of sound
Implementation Method 3
accurate fluid measurements require a homogeneous fluid from which to measure the speed of sound. When the fluid is aerated the path of the ultrasonic sound waves are dispersed by the presence of air bubbles
Data Source
AI summary
A fluid sensor for sensing at least one characteristic of a fluid. The fluid sensor including a sensing area; a sensing element configured to sense a characteristic of a fluid located within the sensing area; and a shroud having a textured area. The shroud configured to allow a liquid portion of the fluid to enter and exit the sensing area, and substantially prohibit a gas portion of the fluid to enter the sensing area.