Composite Assembly for Motor Vehicle Sensor Acoustic Optimization
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Solution Overview
Problem
Concealed mounting of distance sensors in motor vehicles leads to reduced efficiency and sensitivity due to ultrasonic wave dispersion through vehicle wall elements, resulting in a 'partial blind range' where sound pressure levels drop significantly at specific angles.
Innovation Solution
A composite assembly with an intermediate element having a contact surface and recesses between the distance sensor and the vehicle wall element, which can include sound-absorbing materials and a damping element, to optimize sound emission characteristics and reduce surface wave spreading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the distance sensor is mounted concealed behind the wall element, then the design of the motor vehicle is not negatively affected by visible distance sensors, but the efficiency of ultrasonic wave dispersion and sensitivity of the distance sensor are reduced
Solution Approach 1:
An intermediate element is introduced between the concealed distance sensor and the wall element to mediate the transmission of ultrasonic waves. This intermediate element with its specific geometric design (truncated cone or plate-shaped with optimized dimensions) serves as a mediator that improves the coupling of acoustic energy from the sensor through the wall element, thereby enhancing sensor sensitivity while maintaining the concealed mounting configuration for aesthetic purposes.
2Shape
If the distance sensor is mounted concealed behind the wall element, then the design is improved, but a partial blind range occurs with sound pressure level drops at ±22 degrees radiation angle
Solution Approach 1:
The geometric parameters of the intermediate element are optimized to change the acoustic emission characteristics. By adjusting dimensions such as the height, base diameter, and top diameter of the truncated cone intermediate element, or the thickness and dimensions of plate-shaped intermediates, the sound pressure level distribution across different radiation angles is modified to reduce the depth and extent of the blind range while maintaining concealed mounting for aesthetic design.
3Reliability
If an intermediate element is used to improve directivity and sensitivity, then the acoustic emission behavior is influenced, but the device complexity increases
Solution Approach 1:
The intermediate element is designed with specific local geometric qualities (truncated cone shape or plate-shaped configuration with optimized dimensions) that are tailored to the local acoustic requirements at the sensor-wall element interface. This localized geometric design provides the necessary acoustic optimization without requiring complex modifications to the entire composite assembly, thereby limiting the increase in device complexity.
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 smooths sound pressure level curves, reducing inadvertent detection and improving sensitivity by maintaining consistent sound pressure levels across critical angles, particularly beneficial for parking aids.
Implementation Method 1
at least one electroacoustic transducer (2) for emitting sound waves
Implementation Method 2
at least one area (31), in which there is no contact between the intermediate element (3) and the wall element (4), is formed within the contact surface (30)
Data Source
AI summary
A composite assembly for a motor vehicle having at least one electroacoustic transducer for outputting sound waves and at least one wall element of the motor vehicle, behind which the transducer is mounted in a concealed manner, wherein an intermediate element for influencing the sound emission behavior is arranged between the transducer and the wall element, the intermediate element having a contact surface facing the wall element for passing on the sound waves. At least one recess is formed within the contact surface, in which recess no contact is made between the intermediate element and the wall element. In this way, it is possible to influence the emission characteristics of the electroacoustic transducer in a very flexible and need-oriented manner.