Electromagnetic Liftgate Latching for Low-Frequency Noise Control
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Solution Overview
Problem
Existing vehicles face challenges in effectively attenuating low-frequency acoustic noise, particularly in vehicles with moveable features like liftgates, due to resonance and flexing, which current solutions like active noise control, structural stiffening, and tuned vibration absorbers are inadequate or aesthetically compromising.
Innovation Solution
Implementing a system with electromagnetically latched liftgates using electromagnetic latches and a control module to constrain acoustic reinforcing motions, utilizing a control module to selectively engage and disengage the latches based on vehicle operating conditions and collision events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If electromagnetic latches are used to constrain liftgate displacement, then low-frequency acoustic noise is attenuated, but device complexity increases
Solution Approach 1:
The patent replaces traditional mechanical vibration isolation systems with electromagnetic latches that use electromagnetic fields to constrain liftgate displacement. This substitution reduces the need for heavy mechanical components while achieving effective noise attenuation through controlled electromagnetic actuation based on detected vibration frequencies.
Solution Approach 2:
The system incorporates vibration sensors that continuously monitor liftgate displacement and feed this information to a control algorithm. The controller adjusts the electromagnetic latch actuation in real-time based on the detected vibration characteristics, creating a closed-loop feedback system that optimizes noise reduction while minimizing unnecessary actuation.
2Object-affected harmful factors
If substantial mass is added to mitigate booming, then low-frequency noise is reduced, but vehicle weight increases
Solution Approach 1:
The patent replaces mass-based vibration mitigation (such as dead mass or heavy tuned vibration absorbers) with an active electromagnetic constraint system. The electromagnetic latches provide the necessary constraint forces without requiring substantial added mass, thereby reducing noise while maintaining vehicle weight efficiency.
Solution Approach 2:
The electromagnetic latches are actuated periodically or on-demand based on detected vibration frequencies rather than being continuously engaged. This periodic actuation provides effective noise mitigation only when needed, avoiding the continuous weight penalty of heavy passive vibration isolation systems.
3Object-affected harmful factors
If TVAs or dead mass are added to liftgate, then booming is mitigated, but vehicle mass increases undesirably
Solution Approach 1:
The patent substitutes passive mechanical vibration absorption systems (TVAs and dead mass) with active electromagnetic latches. This substitution eliminates the need for additional mass while achieving effective booming mitigation through controlled electromagnetic forces that constrain liftgate displacement at problematic frequencies.
Solution Approach 2:
The system transitions from static, fixed-mass vibration mitigation to a dynamic, adaptive electromagnetic constraint system. The electromagnetic latches can adjust their actuation characteristics in real-time based on operating conditions and detected vibration frequencies, providing effective noise control without the fixed mass requirements of traditional approaches.
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
Effectively attenuates low-frequency acoustic noise by constraining liftgate movements, providing improved noise reduction without adding substantial mass or compromising vehicle aesthetics.
Implementation Method 1
at least one selectively engageable electromagnetic latch effective in an energized state to attract the liftgate toward the vehicle to constrain liftgate displacement
Data Source
AI summary
An in vehicle noise improvement system includes a liftgate hingedly attached and mechanically latched to a body structure in a closed position. At least one selectively energized electromagnetic latch reduces liftgate induced structure borne noise by constraining liftgate displacements under vehicle running condition.