Floatless Pulsed Waveguide Level Measurement
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Solution Overview
Problem
Existing liquid level sensors for urea tanks in SCR systems face challenges due to urea's corrosiveness and non-uniform tank shapes, requiring complex detection methods and often using float-based systems that are not suitable for corrosive environments.
Innovation Solution
A floatless pulsed waveguide liquid level sensing system using a conductive coil wrapped around an inner cylinder, where pulses are transmitted and reflected based on impedance or permittivity changes between the liquid and adjacent media, allowing for level measurement without a float and simpler electronics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If float-based liquid level sensors are used in urea tanks, then liquid level measurement can be achieved, but the sensor is susceptible to corrosion from urea and requires complex detection methods
Solution Approach 1:
The patent replaces the mechanical float-based level sensing system with an electromagnetic pulsed waveguide system. The waveguide transmits electromagnetic pulses through the tank wall to detect liquid level based on dielectric constant changes, eliminating mechanical floats and complex sensing electronics that are susceptible to urea corrosion.
Solution Approach 2:
The patent introduces the tank wall as an intermediary medium for electromagnetic wave transmission. The waveguide system transmits pulses through the non-conductive tank wall to reach the liquid, using the wall itself as part of the sensing path rather than requiring direct contact sensors that would corrode.
2Measurement precision
If capacitance-based probes are used to measure liquid level, then level detection is possible, but the system requires complex detection and sensing electronics
Solution Approach 1:
The patent replaces complex capacitance-based electronic sensing with a simpler pulsed electromagnetic wave transmission system. By measuring the time delay of reflected pulses rather than continuous capacitance changes, the system achieves accurate level detection with simpler electronics that are less susceptible to interference and corrosion.
3Adaptability or versatility
If traditional liquid level sensors are used in tanks with non-uniform shapes, then level measurement is challenging, but adapting sensors to various geometries increases system complexity
Solution Approach 1:
The patent creates a universal pulsed waveguide system that can measure liquid levels in tanks of any geometry. The electromagnetic waves transmit through the tank wall regardless of shape, and the time-delay measurement method adapts automatically to different configurations without requiring specialized sensors for each tank geometry.
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
Enables accurate and cost-effective liquid level measurement in corrosive environments, such as urea tanks, with reduced complexity and increased robustness, suitable for various liquid levels and tank geometries.
Implementation Method 1
the pulsed waveguide is arranged to generate a first delay between a first initial pulse and a first reflected pulse when an upper surface of the liquid is at a first level
Implementation Method 2
the reflection is caused by either (i) a change in impedance or permittivity between the liquid and an adjacent medium
Implementation Method 3
the reflection is caused by either (i) a change in impedance or permittivity between the liquid and an adjacent medium
Data Source
AI summary
A waveguide arrangement may include a tank defining a chamber for holding a liquid; and a pulsed waveguide (PWG) disposed at least partially within the chamber, the PWG comprising: an inner cylinder, the inner cylinder being grounded. The waveguide may also include an electrically conductive coil wrapped around the inner cylinder, wherein the pulsed waveguide is arranged to generate a first delay between a first initial pulse and a first reflected pulse when an upper surface of the liquid is at a first level, and to generate a second delay between a second initial pulse and a second reflected pulse when the upper surface of the liquid is a second level.