Composite Guide Sleeve for Powertrain Mount NVH Reduction
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Solution Overview
Problem
Existing powertrain mounting assemblies are susceptible to noise, vibration, and harshness (NVH) issues due to the stack up of tolerances, which causes the guide sleeve to vibrate axially, leading to noise and vibration transmission to the vehicle cabin.
Innovation Solution
A composite guide sleeve with an elongate tubular body comprising a rigid body portion and a compressible body portion is used. The rigid body portion guides the fastening element through the isolator, while the compressible body portion is axially deformable, ensuring engagement with opposing surfaces of the mounting assembly and minimizing axial clearance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a rigid guide sleeve is used to guide the fastening element through the isolator, then the alignment and engagement are improved, but axial clearance and vibration occur due to tolerance stack up
Solution Approach 1:
The guide sleeve material properties are changed from completely rigid to having controlled elastic deformation capabilities. The sleeve is designed to deform elastically under compression to take up axial clearance caused by tolerance stack up, thereby eliminating vibration and noise while maintaining alignment precision during assembly.
Solution Approach 2:
The guide sleeve is made from composite materials or a single material with graded properties that combine rigidity for alignment with controlled elasticity for clearance absorption. This allows the sleeve to provide both precise guidance and vibration-free operation by deforming to eliminate gaps between components.
2Measurement precision
If the guide sleeve is made completely rigid to maintain alignment, then positioning accuracy is improved, but the tolerance stack up causes axial clearance and NVH issues
Solution Approach 1:
The mechanical parameters of the guide sleeve are optimized to balance rigidity and elasticity. The sleeve has sufficient stiffness to maintain positioning accuracy during assembly but controlled flexibility to deform and eliminate axial clearance, thereby improving NVH performance without sacrificing positioning precision.
Solution Approach 2:
The guide sleeve transitions from a static rigid structure to a dynamic component that can deform elastically under load. This dynamic capability allows the sleeve to adapt to tolerance variations and eliminate gaps that cause vibration, while maintaining the necessary rigidity for accurate positioning during the assembly process.
3Manufacturing precision
If a rigid guide sleeve is used, then the fastening element alignment is improved, but the isolator can be damaged due to snagging during assembly
Solution Approach 1:
The guide sleeve's mechanical properties are adjusted to have controlled elasticity that allows it to deform during assembly. This deformation capability enables the sleeve to pass through the isolator smoothly without snagging, while still providing the rigidity needed for precise alignment of the fastening element.
Solution Approach 2:
The guide sleeve is designed with dynamic deformation characteristics that allow it to flex during the assembly process. This flexibility enables the sleeve to navigate through the isolator without causing damage, while maintaining the alignment function throughout the assembly operation.
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 composite guide sleeve effectively mitigates NVH issues by ensuring secure engagement with the mounting assembly surfaces, reducing axial movement, and thus minimizing noise and vibration transmission to the vehicle cabin.
Implementation Method 1
A modulus of elasticity of the second material is lower than that of the first material so that the compressible body portion is axially deformable between the opposing surfaces of the powertrain mounting assembly by a preload of the fastening
Implementation Method 2
the guide sleeve acts to guide the fastening element through the isolator when the two sub-assemblies are joined together
Data Source
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AI summary
According to an aspect of the present invention there is provided a composite guide sleeve for a fastening element of a powertrain mounting assembly. The guide sleeve comprises: an elongate tubular body extending from a first end to an opposing second end, the tubular body comprising: a rigid body portion and a compressible body portion arranged along the length of the tubular body; and a bore extending from the first end to the second of the tubular body for receiving the fastening element so that, in use, the sleeve guides the fastening element through an isolator of the powertrain mounting assembly so as to join, via the isolator, a vehicle powertrain to a chassis of the vehicle, with the guide sleeve arranged between opposing surfaces of the powertrain mounting assembly. The rigid body portion is formed of a first material and the compressible body portion is formed of a second material. A modulus of elasticity of the second material is lower than that of the first material so that the compressible body portion is axially deformable between the opposing surfaces of the powertrain mounting assembly by a preload of the fastening.