Wavy Perimeter Decoupler for Chortle Noise Reduction
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Solution Overview
Problem
Hydraulically damped powertrain mounts generate noise, known as decoupler 'chortle', due to the decoupler component's contact with perforated plates under high amplitude vibrations, which is a persistent NVH issue as sound quality improves in vehicles.
Innovation Solution
A decoupler design with a non-planar, wavy contour and varying thickness, minimizing contact areas with plates and using hydraulic pressure to create a seal without creasing, made from elastomeric materials without requiring surface irregularities like pits or bumps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a simple flat decoupler design is used, then manufacturing is easy and cost is low, but decoupler chortle noise is generated under high amplitude vibrations
Solution Approach 1:
The patent applies curvature by replacing the flat decoupler surface with a wavy or contoured surface profile. This curved geometry reduces the contact area between the decoupler and the plates during operation, thereby minimizing the impact that generates chortle noise while maintaining the decoupler's primary function of separating fluid chambers
2Object-generated harmful factors
If decoupler surface area is reduced to minimize contact noise, then chortle noise is reduced, but damping capacity may be compromised
Solution Approach 1:
The patent applies local quality by creating a decoupler with non-uniform thickness distribution and varying material properties across different regions. The wavy profile creates areas of different stiffness, allowing the decoupler to maintain adequate contact area for damping while having reduced contact at specific high-noise zones
3Adaptability or versatility
If decoupler travel is increased to improve decoupling function, then vibration isolation is enhanced, but contact noise with plates increases
Solution Approach 1:
The wavy or contoured surface profile allows the decoupler to achieve greater effective travel and adaptation to vibration conditions while the curved geometry ensures that contact with the plates occurs at reduced areas, minimizing noise generation even during large amplitude movements
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
Significantly reduces chortle noise while maintaining damping performance and preventing permanent deformation, ensuring consistent noise reduction without altering the damping profile or peak damping magnitude.
Implementation Method 1
A decoupler used in a hydraulically damped mount includes a body having a perimeter surface with a non-planar conformation and an interior region extending inwardly from the perimeter surface that also has a non-planar conformation
Implementation Method 2
The pumped fluid oscillates through a tube called an inertia track which creates a fluid resonance system and associated damping to dissipate the vibration energy
Implementation Method 3
The pumped fluid oscillates through a tube called an inertia track which creates a fluid resonance system and associated damping to dissipate the vibration energy
Implementation Method 4
The decoupler is formed of a rubber or an elastomeric material
Data Source
AI summary
A reduced noise decoupler has a perimeter with a wavy form. This provides a significant reduction in the initial contact noise. Hydraulic pressure deforms the wavy edges, pressing the wavy edge flat and creating the necessary seal. The edge geometry is created such that pressure will flatten the decoupler perimeter without creasing, ensuring a proper seal without losses. This is achieved by drawing the wavy detail from the perimeter to an interior of the decoupler body in alternating fashion to create a pattern of peaks and troughs bounded by thicker sections, allowing the edges to easily deform without creasing.