Tuned Resilient Bush Structure for Eigenmode Stiffness Reduction
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Solution Overview
Problem
Existing vibration isolation bushes exhibit increased dynamic stiffness at eigenmodes, leading to reduced vibrational isolation between interconnected components, particularly at frequencies associated with normal operation of machinery like engines and chassis in vehicles.
Innovation Solution
A bush with a tuning element integrally formed with the resilient body, featuring an upstanding wall or wing on its outer surface, configured to reduce dynamic stiffness increases associated with eigenmodes within a predetermined operational vibration frequency range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a resilient body is used to isolate vibrations between components, then vibration isolation is improved, but dynamic stiffness increases at eigenmodes reducing isolation effectiveness
Solution Approach 1:
The patent applies mechanical vibration principles by introducing a tuning element that generates counter-vibrations to cancel out the eigenmode vibrations of the resilient body. The tuning element is designed to vibrate at the same frequency as the eigenmode but with opposite phase, thereby reducing the dynamic stiffness increases and maintaining vibration isolation effectiveness across a broader frequency range.
Solution Approach 2:
The patent changes the physical parameters of the vibration isolation system by adding a tuning element with specific mass, stiffness, and damping characteristics. This element is configured to modify the dynamic response of the resilient body, shifting or reducing the eigenmode peaks in the frequency spectrum to improve isolation performance in the operational frequency range.
2Reliability
If the resilient body configuration is optimized for low frequency isolation, then low frequency vibration isolation is improved, but high frequency eigenmodes still cause stiffness increases
Solution Approach 1:
The tuning element is specifically designed to address high frequency eigenmodes while preserving low frequency isolation characteristics. By carefully selecting the mass and stiffness of the tuning element, it can be made to resonate at high frequency eigenmodes and provide counter-vibrations without interfering with the low frequency vibration isolation performance of the main resilient body.
3Ease of manufacture
If a simple resilient body structure is used, then manufacturing complexity is reduced, but vibration isolation performance deteriorates due to eigenmode stiffness peaks
Solution Approach 1:
The patent merges the tuning element with the resilient body into a single integrated component. The tuning element can be formed as an integral part of the resilient body during the molding process, or as a separately manufactured element that is bonded or mechanically attached to the resilient body. This integration maintains manufacturing simplicity while achieving improved vibration isolation performance through the combined action of the resilient body and tuning element.
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 bush effectively reduces dynamic stiffness peaks at eigenmodes, ensuring improved vibrational isolation across the desired operational frequency range, thereby reducing unwanted noise and enhancing the performance of components like electric vehicle motors.
Implementation Method 1
a bush for isolating vibrations, the bush comprising: a first anchor part that defines a longitudinal axis; a second anchor part spaced from the first anchor part; a resilient body extending between the first anchor part and the second anchor part and operably engaged with the first anchor part and the second anchor part to isolate vibrations therebetween
Implementation Method 2
the resilient body may be compressed between the first and second anchor parts when the bush is in use
Implementation Method 3
the tuning element is configured to reduce dynamic stiffness increases associated with eigenmodes of the resilient body within a predetermined operational vibration frequency range
Data Source
AI summary
A tuning element that can be integrally formed with a resilient body of a bush and configured to reduce dynamic stiffness increases associated with eigenmodes of the resilient body within a predetermined operational vibration frequency range. The tuning element may resemble an upstanding wall or wing on an outer surface of the resilient body. The resilient body may comprise a plurality of radial arms having axial passageways therebetween. The tuning element may bridge the passageways. A bush configured in this way may be particular suitable for use in scenario where the operational vibration frequency range comprises high frequency, such as an engine mount for an electric vehicle.