Ultrasonic Urea Sensor Dual-Probe Segmentation
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Solution Overview
Problem
Current ultrasonic quality sensors for SCR systems face challenges in accurately detecting urea concentration at high temperatures due to signal attenuation and bubble formation, leading to incorrect concentration measurements and system crashes.
Innovation Solution
The implementation of a dual-probe assembly with a cylindrical ring and a control module that uses two ultrasonic transducers, a temperature sensor, and advanced signal processing to capture the first wave echo within one pulse cycle, reducing bubble formation and signal attenuation, and employing a sampling strategy that minimizes noise interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-send, single-receive ultrasonic probe structure is used, then size and cost are reduced, but signal attenuation and aftershock interference increase
Solution Approach 1:
The single probe is segmented into two separate probes: a transmitting probe and a receiving probe. This segmentation allows each probe to be optimized for its specific function, with the receiving probe positioned farther from the transmitter to minimize aftershock interference and the transmitting probe designed to maximize ultrasonic wave generation efficiency.
2Measurement precision
If ultrasonic wave flight distance is increased to cover full concentration range, then measurement accuracy improves, but signal attenuation increases
Solution Approach 1:
The system dynamically adjusts the ultrasonic wave flight distance based on the measured concentration range. For high concentration measurements, a shorter flight distance is used to minimize attenuation, while for low concentration measurements, a longer flight distance is employed to achieve full detection range. This dynamic adjustment ensures optimal signal strength across all concentration levels.
3Reliability
If batch data acquisition methods are used to establish detection tables, then measurement reliability improves, but response time increases
Solution Approach 1:
The system performs preliminary calibration measurements during system initialization to establish the relationship between ultrasonic wave parameters and urea concentration. This preliminary action creates a lookup table that can be quickly queried during actual operation, eliminating the need for time-consuming batch data acquisition and fitting functions during real-time measurement.
4Adaptability or versatility
If high temperature operation is permitted to expand detection range, then adaptability improves, but bubble formation and signal attenuation worsen
Solution Approach 1:
A heating element is introduced as an intermediary component to actively control the temperature of the urea solution in the detection chamber. By maintaining the solution temperature below the bubble formation threshold, the heating element prevents bubble formation while still allowing the system to operate across a wide temperature range, thus eliminating the harmful effect of bubbles without sacrificing adaptability.
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 solution enables accurate urea concentration detection across the full range within one pulse cycle, reducing errors and system crashes, even at high temperatures, by effectively washing away bubbles and improving the signal-to-noise ratio.
Implementation Method 1
The basic principle of the detection of concentration is that the flight speed of the ultrasonic wave in the solution of different concentrations is different, as long as we can obtain the flight time of the ultrasonic wave in the solution Δt
Implementation Method 2
The technology used to capture time-of-flight Δt is called TOF (Time Of Fly)
Implementation Method 3
at high temperatures, ultrasonic signals cause collapse in TOF time Δt
Data Source
AI summary
The ultrasonic quality sensor includes a probe assembly, a control module, an ultrasonic probe base, a probe filter, a temperature sensor, and a probe top cover; The probe assembly consists of a transmitting and a receiving transducer to form a face-to-face layout and the ultrasonic flight distance h, h≤(V0*V50)*T0/(V50−V0), where T0 is the pulse width, V0 is the ultrasonic speed at 4° C. in water, V50 is the ultrasonic speed at 50% urea and 70° C. Sampling timing tb∈[t0, t0+C], where C=(N+1)*T0, t0=h/V0, N is the number of ultrasonic actuating pulses. tr and td are first rising edge trigger timing and first falling edge trigger timing; As long as td−tr exceeds a certain percentage of T0, the chip can catch timing tf after tb of wave rising edge crosses zero. The cylindrical ring has small holes to carry away bubbles during high-temperature stages.