Vehicle Suspension Bushing Axial Retainer Preload NVH
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Solution Overview
Problem
Existing vehicle suspension bushing assemblies experience noise, vibration, and harshness (NVH) issues due to longitudinal movement of the thrust bearing, leading to free play and accelerated wear, which reduces service life and increases manufacturing costs.
Innovation Solution
The improved vehicle suspension bushing assembly incorporates an inner sleeve, a bearing, an intermediate sleeve, an outer sleeve, and an axial retainer with a preload feature that applies a longitudinal preload force to the intermediate sleeve and bearing, eliminating free play by translating from an uncompressed to a compressed position, thereby reducing NVH and enhancing durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the thrust bearing is allowed to move longitudinally relative to the inner metal sleeve to accommodate operational loads, then the bushing assembly can handle vehicle suspension forces, but free play develops causing noise, vibration, harshness (NVH) problems and accelerated wear
Solution Approach 1:
The axial retainer applies a preliminary preload force in the opposite direction to the expected operational loads. By pre-compressing the thrust bearing against the inner metal sleeve, the retainer eliminates free play before loads are applied, preventing the clicking noise and vibration that would otherwise occur during operation.
Solution Approach 2:
The axial retainer is positioned and preloaded during assembly to establish the correct initial position of the thrust bearing and intermediate sleeve. This preliminary positioning action ensures that components are properly aligned and free-play-free before the bushing assembly enters service, improving NVH performance from the start.
2Reliability
If precise tolerances are specified for the thrust bearing and intermediate sleeve to eliminate free play, then NVH performance improves, but manufacturing costs increase
Solution Approach 1:
Instead of controlling NVH performance through tight dimensional tolerances on the thrust bearing and intermediate sleeve, the invention changes the approach by introducing a preload parameter. The axial retainer applies a controlled preload force that actively eliminates free play, allowing for more relaxed tolerances while maintaining the same NVH performance level.
Solution Approach 2:
The axial retainer acts as an intermediary component between the inner metal sleeve and the thrust bearing assembly. It mediates the interaction by applying a controlled preload force that eliminates free play without requiring precise manufacturing tolerances on the other components, thereby reducing manufacturing costs while improving reliability.
3Reliability
If the axial retainer applies a preload force to eliminate free play, then NVH performance and durability improve, but the device complexity increases
Solution Approach 1:
The axial retainer performs multiple functions within a single component: it positions the thrust bearing, applies the preload force to eliminate free play, and maintains this preload during operational loads. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in device complexity while achieving improved NVH performance and durability.
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 effectively reduces noise, vibration, and harshness while improving durability and service life without increasing manufacturing costs, as the axial retainer's preload force maintains proper alignment and reduces wear, eliminating the need for precise tolerances.
Implementation Method 1
The preload feature of the axial retainer is resilient. In operation, the preload feature of the axial retainer deflects from an unbiased position when the axial retainer is in the uncompressed position to a biased position when the axial retainer is in the compressed position. Because the preload feature of the axial retainer is resilient, the preload feature applies a longitudinal preload force to at least one of the intermediate sleeve and the bearing
Implementation Method 2
The elastomeric bushing operates to isolate the vehicle from shock. The elastomeric bushing, which is located between the outer metal sleeve and the thrust bearing, effectively isolates the frame of the vehicle from the unsprung components
Data Source
AI summary
A vehicle suspension bushing assembly including an inner sleeve, a bearing, an intermediate sleeve, an outer sleeve, and a bushing. The inner sleeve extends longitudinally between first and second inner sleeve ends. The bearing extends annularly about the inner sleeve, the intermediate sleeve extends annularly about the bearing, and the outer sleeve extends annularly about the intermediate sleeve. The bushing is positioned radially between the outer sleeve and the intermediate sleeve. Axial retainers extend annularly about the first and second inner sleeve ends. The axial retainers are longitudinally moveable relative to the inner sleeve. The axial retainers have a preload feature including a flange segment that is resilient and deflects from an unbiased position when the axial retainers are in an uncompressed position to a biased position when the axial retainers are in a compressed position to apply a longitudinal preload force to the intermediate sleeve.