Unitary Wire Mesh Heat Shield Isolator
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Solution Overview
Problem
Existing heat shields in exhaust systems face issues with differential thermal expansion and vibration, leading to failed connections and noise due to the use of two-part wire mesh isolators that can unwind and become dislodged during transportation and assembly.
Innovation Solution
A unitary wire mesh isolator is integrated into the heat shield with a press apparatus forming the isolator in place, using a tool with sleeves and mandrels to compress the mesh into flanges, eliminating the need for separate parts and ensuring secure attachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If two-part wire mesh isolators are used, then the heat shield can be attached to the muffler, but the isolators can unwind and become dislodged during transportation and assembly
Solution Approach 1:
The patent combines two separate wire mesh isolators (collar and grommet) into a single integrated unitary isolator. The collar portion forms a flange on the heat shield, while the grommet portion is compressed into the flange in a single continuous structure, eliminating the risk of the two parts separating or unwinding during handling and assembly.
Solution Approach 2:
The unitary isolator is designed with distinct functional segments: a collar portion that forms a flange on the heat shield, and a grommet portion that compresses into the flange. This segmentation allows each part to perform its specific function while maintaining structural integrity as a single piece.
2Strength
If welded attachments are used between heat shield and muffler, then strong connection is achieved, but the weldments are subject to substantial forces from differential thermal expansion and vibration
Solution Approach 1:
The wire mesh isolator acts as a flexible mechanical element that can deform to accommodate differential thermal expansion between the heat shield and muffler. The knitted wire mesh structure provides flexibility while maintaining strength, allowing the connection to withstand thermal and vibrational stresses without failure.
Solution Approach 2:
The isolator design allows for dynamic movement and deformation to accommodate thermal expansion and vibration. The compressible grommet portion can flex and adjust during operation, providing a dynamic connection that adapts to changing conditions rather than being rigid and fixed.
3Temperature
If the heat shield is spaced from the muffler to provide heat shielding, then thermal insulation is achieved, but the connection becomes subject to vibration and thermal expansion forces
Solution Approach 1:
The wire mesh isolator provides a flexible connection that maintains the necessary spacing for heat shielding while accommodating thermal and vibrational stresses. The knitted structure allows the isolator to flex and deform without failing, maintaining both the thermal gap and connection integrity.
4Adaptability or versatility
If folded connections are used between heat shield and muffler, then some motion during thermal expansion is accommodated, but folds generate objectionable noise during vibration
Solution Approach 1:
The wire mesh isolator provides a flexible connection that accommodates thermal expansion through the compressible grommet portion while maintaining smooth surfaces that do not generate noise during vibration. The knitted structure allows motion without the sharp folds that create objectionable noise.
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
The solution provides a stable, noise-reducing, and vibration-resistant heat shield with integrated isolators that remain secure during thermal expansion and vibration, allowing for direct shipment and easy assembly, preventing the issues of dislodgment and noise associated with two-part systems.
Implementation Method 1
a press apparatus adapted to support a heat shield having predefined locations and number of bores for accepting isolators
Implementation Method 2
heat shield having a bore between first and second surfaces and having a unitary wire mesh isolator formed in the bore
Implementation Method 3
The temperature differential between the heat shield and the muffler leads to differential thermal expansion
Data Source
AI summary
A substrate such as a heat shield for a vehicle is provided with a unitary compressed wire mesh bushing or isolator formed in place though a bore in the substrate. The bushing is formed by supporting an uncompressed or partially compressed wire mesh sleeve, optionally including a grommet or spacer, on a mandrel positioned within the bore; the mandrel is surrounded on either side of the bore by outer sleeves forming a molding cavity on each side of the substrate, and a slidable tamp is disposed in each outer sleeve and moved towards each other to compress the mesh within the bore and provide the unitary bushing.