Directional Ultrasonic Sensor for Urea Concentration and Level
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Solution Overview
Problem
Current ultrasonic sensors for measuring urea solution concentration and fluid level in vehicle tanks require multiple transducers, increasing complexity and cost, while existing solutions struggle with thermal and aging-related accuracy issues.
Innovation Solution
A directional ultrasonic sensor with a single transducer capable of emitting and receiving sound in multiple directions, utilizing a membrane with variable thickness and elevations/depressions to create a main lobe and side lobes for multiple transit time measurements, allowing for concentration determination and fluid level measurement with reduced hardware complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple transducers are used to enable multiple measuring sections (concentration measurement and fluid level measurement), then measurement functionality is improved, but device complexity and cost increase
Solution Approach 1:
A single ultrasonic transducer is designed with a directional characteristic that enables it to perform multiple measuring functions. The transducer emits ultrasonic waves in multiple directions (main lobe and side lobes), allowing it to measure both the concentration of urea solution through transit time measurement in the main lobe and the fluid level through reflection measurement in the side lobes, thereby eliminating the need for separate transducers for each measurement task
Solution Approach 2:
The directional characteristic of the transducer is segmented into multiple lobes (main lobe and side lobes), where each lobe serves a specific measurement purpose. The main lobe is directed toward the reflector for concentration measurement, while the side lobes are directed toward the fluid surface for level measurement, allowing functional segmentation within a single transducer
2Device complexity
If a single transducer with directional characteristic is used, then device complexity is reduced, but achieving accurate multi-directional emission and reception requires complex membrane design
Solution Approach 1:
The membrane of the transducer is designed with non-uniform thickness, where different regions of the membrane have different thicknesses to control the phase and amplitude of ultrasonic waves in different directions. This local variation in membrane thickness creates the desired directional characteristic with main and side lobes, allowing accurate multi-directional emission without requiring multiple transducers
3Measurement precision
If conventional ultrasonic measurement is used, then thermal and aging-related changes affect measurement accuracy, but no additional complexity is introduced
Solution Approach 1:
The system uses the side lobes of the transducer to continuously monitor the fluid level and the main lobe to measure the concentration of urea solution. By having both measurement paths available simultaneously, the system can use the fluid level information to compensate for thermal expansion effects and use the concentration measurement to correct for aging-related changes in the ultrasonic path, thereby maintaining measurement accuracy without requiring additional complex compensation hardware
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 measurement of urea solution concentration and fluid level using a single transducer, improving measurement accuracy and reducing costs by eliminating the need for multiple sensors, while minimizing the impact of thermal and aging-related changes.
Implementation Method 1
a transducer (6) that can be used as an ultrasonic transmitter and/or as an ultrasonic receiver
Implementation Method 2
The directional characteristic is such that the transducer emits sound in at least two different directions and/or receives sound from at least two different directions
Implementation Method 3
The membrane has a variable thickness d with multiple protrusions and/or multiple depressions; and/or a directional element is attached to the membrane, which has a variable thickness d with multiple protrusions and/or multiple depressions
Implementation Method 4
the concentration of the urea solution can be determined by determining the transit times of ultrasound signals in the urea solution
Implementation Method 5
Since the speed of sound in the urea solution is a function of the concentration, the concentration of the urea solution can be determined by determining the transit times of ultrasound signals in the urea solution
Implementation Method 6
When measuring the fill level, the travel time of a sound wave emitted by and received from an ultrasonic transducer is typically measured. The transducers typically emit in a vertical direction, and the sound signal is reflected at the fluid surface
Data Source
Figure 1~2
Figure 3~4
Figure 5A~5C
AI summary
The invention relates to an ultrasonic sensor (3) for measuring transit time in a medium (4), in particular in a fluid (4), which ultrasonic sensor comprises an acoustic transducer (6) which can be used as an ultrasonic transmitter (6a) and/or as an ultrasonic receiver (6b). The acoustic transducer (6) is designed such that the acoustic transducer emits sound in at least two different directions (R1, R2a, R2b) and/or receives sound from at least two different directions (R1, R2a, R2b).