Ultrasonic Sensor Assembly With Acoustic Metamaterial Screening
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Solution Overview
Problem
Existing ultrasonic sensors for vehicles face challenges in achieving high signal-to-noise ratios and are susceptible to structural vibrations when covered, leading to reduced measurement accuracy and increased background noise.
Innovation Solution
Incorporating a broadband acoustic metamaterial screen section in front of the ultrasonic membrane, which allows ultrasonic waves to pass through non-resonantly, maintaining signal amplitude while decoupling the membrane from the housing and any covering structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an ultrasonic sensor is covered with a paneling part or housing, then the sensor is protected and integrated into the vehicle structure, but structural vibrations are transmitted to the sensor membrane reducing measurement accuracy
Solution Approach 1:
A damping layer is introduced as an intermediary between the paneling part and the sensor membrane. This damping layer absorbs and isolates structural vibrations from the paneling, preventing them from being transmitted to the sensor membrane while allowing the sensor to remain covered and protected.
Solution Approach 2:
The damping layer is designed with a porous structure that allows it to effectively absorb and dissipate vibrational energy from the paneling part. The porous material properties enable the layer to reduce structure-borne noise while maintaining the protective covering function.
2Measurement precision
If damping elements are added to reduce structure-borne noise, then measurement accuracy improves, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The damping layer is integrated directly into the paneling part structure, merging the damping function with the existing protective covering. This integration approach reduces the number of separate components and simplifies the overall assembly process while maintaining vibration reduction effectiveness.
Solution Approach 2:
The damping characteristics are optimized by adjusting parameters of the damping layer such as material composition, thickness, and porous structure. These parameter changes enable effective vibration reduction with a simple, integrated design rather than requiring complex multi-component assemblies.
3Measurement precision
If the ultrasonic sensor is arranged uncovered, then signal-to-noise ratio is maximized, but the sensor lacks protection and cannot be integrated into vehicle body panels
Solution Approach 1:
A screen section made of acoustic metamaterial is introduced as an intermediary between the external environment and the sensor membrane. This screen section allows ultrasonic signals to pass through effectively while providing physical protection and enabling integration into vehicle body panels.
Solution Approach 2:
The screen section is constructed from acoustic metamaterials with specific composite structures that enable selective acoustic transmission. These composite materials allow ultrasonic frequencies to pass through while blocking other forms of interference and providing mechanical protection.
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 solution significantly enhances echo signal amplitudes by up to a factor of 10 and improves the signal-to-noise ratio, while providing protection and reducing structural vibrations, making it suitable for concealed installations.
Implementation Method 1
a screen section arranged in front of the ultrasonic membrane and made of an acoustic metamaterial which allows ultrasonic waves to pass through non-resonantly
Implementation Method 2
a sound transducer element for exciting vibrations and detecting vibrations of the ultrasonic membrane; The ultrasonic membrane, stimulated by the transducer element, emits energy in the form of an ultrasonic signal
Implementation Method 3
The sound transducer element then detects vibrations in the ultrasonic membrane, which originate from an echo signal returning from the motor vehicle vicinity or the interior
Implementation Method 4
an ultrasonic sensor having a housing, an ultrasonic membrane mechanically decoupled from the housing
Data Source
AI summary
An ultrasonic sensor assembly (1) for a motor vehicle (16) comprises: an ultrasonic sensor (2) having a housing (4), an ultrasonic membrane (5) mechanically decoupled from the housing (5) and a sound transducer element (7) for exciting vibrations and detecting vibrations of the ultrasonic membrane (5); and a screen section (3) arranged in front of the ultrasonic membrane (5) and made of an acoustic metamaterial. The metamaterial is preferably a broadband metamaterial, which can be tunneled in a non-resonant manner in an angular range. The screen section (3) may preferably be formed in a shaped part (13), such as a bodywork metal sheet of the exterior skin or an interior paneling, of the motor vehicle (16).