Ultrasonic Sensor Intermediate Element for Thermal Expansion
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Solution Overview
Problem
The challenge lies in creating a reliable and durable connection between a ceramic stiffening element and a polypropylene bumper for ultrasonic sensors, which must withstand varying temperatures and linear expansion coefficients, while minimizing vibrational loss and ensuring a strong, long-lasting bond.
Innovation Solution
An intermediate element made of a material with a linear expansion coefficient between that of the ceramic and polypropylene is used, bonded to both the stiffening element and the bumper using different adhesives, with a plate-shaped intermediate element providing a firm connection and reducing vibrational loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a ceramic stiffening element is firmly connected to a polypropylene bumper, then the connection strength and vibration transmission are improved, but the difference in linear expansion coefficients causes connection failure under temperature variations
Solution Approach 1:
An intermediate element made of aluminum is introduced between the ceramic stiffening element and the polypropylene bumper. This intermediate element acts as a mediator that can be firmly connected to both materials while accommodating their different linear expansion coefficients, thus maintaining connection reliability under temperature variations.
Solution Approach 2:
The connection system uses a composite structure consisting of three different materials: ceramic (stiffening element), aluminum (intermediate element), and polypropylene (bumper). Each material is selected for its specific properties, and the combination allows the system to achieve both strong connection and thermal expansion compatibility.
2Reliability
If a soft adhesive is used to compensate for linear expansion differences, then the connection reliability is improved, but the vibration transmission efficiency is reduced
Solution Approach 1:
The aluminum intermediate element serves as a mediator that mechanically bridges the ceramic and polypropylene components. It allows the use of adhesives optimized for each material interface without requiring a single adhesive to simultaneously handle both thermal expansion compensation and vibration transmission, thus resolving the trade-off between reliability and energy loss.
3Loss of energy
If a hard adhesive is used for strong vibration transmission, then the energy loss is reduced, but the adhesive is brittle and cannot compensate for material expansion differences
Solution Approach 1:
The connection system is segmented into two separate adhesive joints: one between the ceramic stiffening element and the aluminum intermediate element, and another between the aluminum intermediate element and the polypropylene bumper. This segmentation allows each adhesive to be optimized for its specific material pair, with the aluminum intermediate element absorbing the thermal expansion differences.
4Reliability
If the membrane is firmly connected to the bumper, then the ultrasonic signal transmission is improved, but the entire bumper area vibrates causing unwanted side effects
Solution Approach 1:
The ceramic stiffening element acts as a mediator that localizes the vibration to a small area around the ultrasonic membrane. By being firmly connected to the bumper through the aluminum intermediate element, it restricts vibration propagation to only the necessary area, preventing unwanted vibrations in the rest of the bumper while maintaining good signal transmission.
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 ensures a robust and efficient transmission of ultrasonic signals, maintaining maximum efficiency and durability across the required temperature range, while allowing for easy assembly and repair of the ultrasonic sensor system.
Implementation Method 1
a plate-shaped intermediate element (14), which is brought into contact with the rear (4) of the trim panel (2) on the one hand and with a front side (13) of the stiffening element (11) on the other hand
Implementation Method 2
bonded to both the stiffening element and the bumper using different adhesives
Data Source
Figure 1~2
Figure 3~4
AI summary
The invention relates to an ultrasonic sensor arrangement (1) for a motor vehicle, comprising a lining part (2) and an ultrasonic sensor (5) which comprises a crucible-shaped membrane (7) for emitting and/or capturing ultrasonic signals, also comprising a reinforcing element (11) which is arranged around the membrane (7) and which comprises a through-opening (12) traversed by the membrane (7). Said ultrasonic sensor (5) and the reinforcing element (11) are arranged on the rear side (4) of the lining part (2) such that said ultrasonic sensor (5) is formed through the protective part (2) for emitting and/or capturing the ultrasonic signals. A plate-shaped intermediate element (14) is arranged between the rear side (4) of the protective part (2) and a front side (13) of the reinforcing element (11), facing the protective part (2), said intermediate element rests on the rear side (4) of the protective part (2) and on the front side (13) of the reinforcing element (11) and is made of a material which is different from that of the reinforcing element (11) and the protective part (2). Said material of the intermediate element (14) has a length expansion coefficient which lies between the coefficients of the respective materials of the reinforcing element (11) and the protective part (2).