Fuel Rail Mounting Arrangement with Stacked-Layer Isolators
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Solution Overview
Problem
Existing vibration isolation mounts for high-pressure fuel rails in direct injection engines suffer from limited damping capabilities and age-related compression reduction, leading to unacceptable noise levels.
Innovation Solution
A vibration isolation fuel rail mounting arrangement featuring stacked-layer isolators with elastomer layers positioned on either side of the mounting portion, utilizing in-plane shear damping and a compression limiter to maintain preload despite elastomer relaxation, with the elastomer layers' mid-width point spaced between 1.5 and 3 times the fastener diameter from the central axis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If simple compression of elastomeric material is used in isolation mounts, then the structure is simple, but damping capabilities are limited
Solution Approach 1:
The elastomeric material is segmented into multiple layers with different properties. The stacked-layer configuration divides the single elastomeric element into distinct layers that can be positioned at specific distances from the central axis, allowing each layer to contribute differently to the overall damping performance while maintaining structural simplicity.
Solution Approach 2:
Different regions of the elastomeric material are given different properties through the stacked-layer design. By positioning layers at specific distances from the central axis (with mid-width points spaced between 1.5d and 3.0d away), the mount provides optimized local damping characteristics in different radial zones, enhancing overall damping capability without significantly increasing complexity.
2Reliability
If compression limiter is added to allow bolt tightening beyond compressive preload, then preload can be maintained, but device complexity increases
Solution Approach 1:
The compression limiter is pre-configured with a specific height that corresponds to the desired compressed state of the elastomeric layers. During assembly, the bolt is tightened until it contacts the compression limiter, which has already been positioned to enforce the correct compression amount. This preliminary positioning of the limiter ensures proper preload maintenance without requiring complex control mechanisms.
3Volume of moving object
If elastomer layers are positioned closer to central axis, then packaging size is reduced, but damping performance decreases
Solution Approach 1:
The invention optimizes the radial position parameter of the elastomeric layers by spacing the mid-width point of each layer's compression area between 1.5d and 3.0d from the central axis. This specific parameter range achieves the optimal balance between damping performance and packaging size. The stacked-layer configuration with controlled radial positioning ensures sufficient damping effectiveness while maintaining compact dimensions suitable for engine bay installation.
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 configuration enhances damping performance while maintaining minimal packaging size, effectively reducing noise from vibrations and ensuring consistent isolation over time.
Implementation Method 1
utilizing in-plane shear damping
Implementation Method 2
the compressed elastomeric material will inherently suffer from compression reduction as the elastomeric material ages
Data Source
AI summary
A vibration isolation fuel rail mounting arrangement is configured for in-plane shear type damping by spacing the mid-width points of the elastomer compression areas of two stacked-layer isolators away from the central fastener axis by a distance between about 1.5 times the bolt diameter and about 3.0 times the bolt diameter.