Urea Sensor Reflector Dome for Thermal Stability
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Solution Overview
Problem
Current urea concentration sensors in diesel engine vehicles face inaccuracies due to temperature variations affecting the positioning of transceivers and reflectors on polymeric urea storage tanks, leading to errors in concentration interpretation.
Innovation Solution
A urea concentration sensor assembly with a dome-shaped reflector and multiple legs supporting it, along with a ceramic piezoelectric sound wave generator and receiver, directs ultrasonic waves upwardly, using a concave-shaped inner surface to concentrate and focus sound waves, reducing the impact of temperature variations and providing a self-cleaning convex dome surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a horizontal sound travel direction is used by positioning transceiver and reflector on polymeric tank wall, then the sensor can be installed on the tank wall, but temperature variation causes misalignment of transceiver and reflector leading to measurement error
Solution Approach 1:
The patent inverts the sound travel direction from horizontal to vertical. The transceiver is positioned on the bottom tank wall and directs sound waves upward to a dome-shaped reflector on the tank's top surface. This inversion eliminates thermal expansion misalignment issues because the vertical configuration with the dome shape maintains proper alignment despite temperature variations in the polymeric tank wall.
Solution Approach 2:
The patent employs a dome-shaped (spheroidal) reflector on the tank's top surface. This curved surface focuses the vertically traveling sound waves back to the transceiver, ensuring accurate measurements. The dome shape compensates for any minor misalignments caused by thermal expansion and maintains consistent sound wave reflection geometry.
2Measurement precision
If temperature versus urea concentration tables are used to compensate for thermal expansion, then approximate concentration can be determined, but error in concentration interpretation occurs
Solution Approach 1:
The vertical sound travel configuration with the dome-shaped reflector creates a self-aligning system that is inherently insensitive to thermal expansion of the polymeric tank wall. The geometry naturally maintains proper transceiver-reflector alignment without requiring external temperature compensation tables or complex correction algorithms, thereby eliminating interpretation errors.
3Productivity
If sound waves travel horizontally between transceiver and reflector, then measurement can be performed, but distance variation between transceiver and reflector influences measured time frame
Solution Approach 1:
The dome-shaped reflector focuses the vertically traveling sound waves back to the transceiver position, maintaining a consistent effective reflection point. This geometric focusing ensures that the sound travel distance remains constant despite variations in tank wall thickness or thermal expansion, thereby improving time frame measurement accuracy.
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 design enhances the accuracy of urea concentration measurement by minimizing the influence of temperature variations and thermal expansion, eliminating the need for temperature vs. concentration tables, and maintaining a fixed height to improve echo signal reliability.
Implementation Method 1
The sound wave generator and receiver generates ultrasonic sound waves directed upwardly toward the reflector
Implementation Method 2
the reflector including a concave-shaped inner surface defining a downward directed ultrasonic focus zone which receives and back-reflects the ultrasonic sound waves
Implementation Method 3
the concave-shaped inner surface reflects and reconfigures the ultrasonic sound waves into a conical shaped ultrasonic cone which concentrates the reflected ultrasonic sound waves
Implementation Method 4
The sound wave generator and receiver is a ceramic piezoelectric element
Implementation Method 5
the bottom tank wall directly below the reflector defines an upwardly directed convex dome surface allowing crystals or particles of urea which form at the bottom tank wall to displace by gravity outwardly and off of the dome surface
Data Source
AI summary
A urea concentration sensor reflector system includes a urea concentration sensor reflector assembly including a reflector having an upwardly convex dome shape integrally connected to and supported by multiple legs. The reflector includes a concave-shaped inner surface. The multiple legs are connected to and support the urea concentration sensor reflector assembly to an upward directed surface of a bottom tank wall of a urea storage tank. A sound wave generator and receiver is fixed to the bottom tank wall directly below and centrally aligned with the reflector. The sound wave generator and receiver generates ultrasonic sound waves directed upwardly toward the reflector. A concentration of a liquid urea in the urea storage tank is determined based on a time for the ultrasonic sound waves to travel to the reflector and return as echo signals to the sound wave generator and receiver, and a temperature of the liquid urea.