Bottom-Up Ultrasonic Level Sensor with Conical Reflector
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Solution Overview
Problem
Conventional ultrasonic sensors for liquid level measurement in vessels face challenges such as a dead zone near the vessel bottom due to transducer housing height and ringing issues, leading to inaccurate measurements and the need for costly vessel modifications, and reverberations causing false readings.
Innovation Solution
An ultrasonic sensor design with a transducer mounted on a plate at the lower end of a tubular probe, using a conical reflector cap for 360° energy transmission and reception, and an optional reflective pin for temperature and viscosity compensation, allowing for accurate liquid level measurement with reduced dead zone.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a transducer housing is used to encapsulate the transducer, then the transducer is protected and sealed, but the housing height creates a dead zone that prevents accurate measurement near the vessel bottom
Solution Approach 1:
The patent removes the traditional transducer housing that caused the dead zone problem. Instead, the transducer is mounted directly on the probe or with a minimal mounting structure that eliminates the housing height issue, allowing ultrasonic measurements to start from the probe tip rather than from a elevated housing position.
Solution Approach 2:
The patent inverts the conventional approach by mounting the transducer at the bottom end of the probe facing upward, rather than at the top end facing downward. This inversion eliminates the dead zone created by housing height and allows the ultrasonic beam to originate from the lowest point of the probe.
2Measurement precision
If the transducer is mounted at the bottom end of the probe, then the dead zone is reduced, but the transducer ringing creates a dead zone between the transducer and the liquid surface
Solution Approach 1:
The patent uses periodic pulsing of the transducer with controlled duration and intervals. The pulse width is carefully selected to be shorter than the ring-down time, and adequate pause periods are implemented between pulses to allow the transducer to stop ringing before the next measurement cycle begins, eliminating the dead zone caused by ringing.
Solution Approach 2:
The patent implements a delay period after each ultrasonic pulse to allow the transducer ringing to decay before initiating the next measurement cycle. This timing skip allows the system to rush through the ringing phase and begin accurate measurement once the transducer has stabilized.
3Adaptability or versatility
If the probe extends deep into the vessel, then the liquid level can be measured at various heights, but the probe becomes more complex and requires additional support structures
Solution Approach 1:
The patent divides the probe into functional segments: an upper section for mounting the transducer and electronics, a middle section for ultrasonic transmission through the liquid, and a lower section with the transducer mounting interface. This segmentation allows each part to be optimized independently and simplifies the overall structure.
Solution Approach 2:
The probe is designed as a multi-functional component that serves as both the structural support element and the ultrasonic transmission medium. The same probe structure that provides mechanical support also serves as the waveguide for ultrasonic energy, eliminating the need for separate support structures.
4Ease of operation
If conventional ultrasonic sensors are used, then the basic liquid level measurement function is provided, but reverberations cause false readings
Solution Approach 1:
The patent implements periodic pulsing with controlled duration and intervals to prevent reverberation. By limiting the pulse width and incorporating adequate pause periods, the system allows complete echo cancellation between pulses, eliminating false readings caused by reverberations while maintaining basic measurement functionality.
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 sensor achieves precise liquid level measurement with a reduced dead zone and improved sensitivity for high viscosity liquids, eliminating the need for vessel modifications and reducing false readings, while enabling separate crystal use for density and temperature compensation.
Implementation Method 1
The transducer 26 usually is of a piezoelectric ceramic material such as PZT (lead-zirconate-titanate). The transducer converts the electrical energy signals into ultrasonic (electro-mechanical) energy
Implementation Method 2
The transducer converts the received ultrasonic energy back into electrical energy signals
Implementation Method 3
The upwardly transmitted ultrasonic energy is reflected from the interface of the liquid 14 and air, or other gas, in the probe downwardly back to the transducer 26
Data Source
AI summary
An ultrasonic sensor for measuring the level of liquid in a vessel has an elongated tubular probe, a tube within the probe, and a transducer that converts electrical energy to ultrasonic energy mounted at or near one end of the tube to transmit ultrasonic energy along the probe longitudinal axis. A conical reflector that reflects ultrasonic energy is opposite the transducer ultrasonic energy emitting part to reflect ultrasonic energy received from the transducer upwardly in the probe to an air-liquid interface from which it is downwardly reflected to the conical reflector element that directs the energy reflected from the interface back to the transducer for conversion to an electrical signal that is used by an electronic module to measure the liquid level in the probe, which is the liquid level in the vessel, by measuring the round trip travel time of the ultrasonic signal energy.