Ultrasonic Sensor Damping with Phase Change Material
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Solution Overview
Problem
Ultrasonic sensors in automotive applications face issues with detecting obstacles due to post-oscillation phases and thermal gradients, leading to malfunction and erroneous readings, particularly when temperature changes occur rapidly.
Innovation Solution
Incorporating a heat accumulator with phase change material, such as polymeric hollow spheres, into the damping element of the ultrasonic sensor to regulate temperature changes, ensuring uniform temperature adjustment and minimizing thermal stresses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the membrane is operated in the resonance range to minimize energy consumption, then energy efficiency is improved, but post-oscillation time increases causing detection failures for nearby obstacles
Solution Approach 1:
The patent extracts the damping function from the main sensor structure by introducing a separate damping element that is acoustically coupled to the membrane. This element is specifically designed to absorb post-oscillations while being acoustically transparent during the transmission phase, thus separating the conflicting requirements of energy efficiency and detection reliability.
Solution Approach 2:
The damping element acts as an intermediary between the membrane and the surrounding medium. It mediates the conflicting requirements by providing acoustic damping during reception while maintaining acoustic transparency during transmission, enabling the system to achieve both low energy consumption and high detection reliability.
2Reliability
If a damping device is added to reduce post-oscillation phase, then detection reliability is improved, but device complexity increases
Solution Approach 1:
The damping element is designed to serve multiple functions: it provides acoustic damping during reception mode while being acoustically transparent during transmission mode. This multi-functionality allows a single component to address detection reliability without proportionally increasing device complexity.
Solution Approach 2:
The patent employs porous or foam-like damping materials that provide effective acoustic damping while maintaining a compact structure. These materials achieve the damping function with minimal added complexity by utilizing their inherent porous structure to absorb acoustic energy.
3Speed
If the sensor components are thermally connected to the environment for quick temperature adjustment, then thermal response time is improved, but thermal gradients cause fluctuating damping and resonance frequency shifts
Solution Approach 1:
The patent applies beforehand cushioning by providing thermal insulation to the damping element and electronic control components before thermal problems occur. This insulation protects these sensitive components from rapid temperature changes, preventing resonance frequency shifts and damping fluctuations until thermal equilibrium is established.
Solution Approach 2:
The patent applies different thermal characteristics to different components: the membrane and piezo element are allowed to thermally equilibrate quickly with the environment, while the damping element and electronic control are thermally insulated. This local differentiation of thermal properties optimizes both thermal response and operational stability.
4Stability of the object's composition
If thermal insulation is applied to protect components from temperature changes, then resonance frequency stability is improved, but thermal response time increases
Solution Approach 1:
The patent selectively applies thermal insulation only to the damping element and electronic control components that are sensitive to temperature changes, while allowing the membrane and piezo element to thermally equilibrate quickly. This localized approach minimizes the overall thermal response time while protecting the critical components that would otherwise be affected by thermal gradients.
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 significantly reduces malfunctions and erroneous readings by maintaining consistent sensor functionality during rapid temperature changes, ensuring reliable obstacle detection and system stability.
Implementation Method 1
the heat accumulator (26) has a phase change material
Implementation Method 2
the thermal energy previously stored in the heat accumulator is released
Implementation Method 3
couple the membrane of the ultrasonic sensor to a damping device, which leads to a rapid decay of the oscillating membrane
Data Source
Figure 1
AI summary
The present invention relates to an ultrasonic sensor (10) with a vibrating membrane (13) and a vibration exciter (14) as well as with a damping device (20) wherein the damping device (20) contains a phase change material.