Tapered Elastomeric Isolator for Vehicle Seat Vibration Damping
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Solution Overview
Problem
Conventional seat suspension systems for vehicles, such as riding lawn mowers, primarily focus on attenuating vertical oscillations and do not effectively address horizontal oscillations, leading to operator discomfort due to limited degrees of freedom and susceptibility to wear and friction issues in dusty environments.
Innovation Solution
A seat isolation system with tapered elastomeric tubular isolators providing six degrees of freedom, including translation and pivoting, to attenuate and dissipate low-frequency oscillations and shock loads in multiple directions, particularly in the horizontal plane, with radial stiffness ranging from 100 to 300 pounds-force/inch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional seat suspension systems use sliding/rolling contact mechanisms to provide horizontal seat movement, then additional degrees of freedom are achieved, but the system becomes susceptible to wear and friction problems in dusty environments
Solution Approach 1:
The patent replaces sliding/rolling contact mechanisms with elastomeric isolators that use elastic deformation to provide horizontal movement. The isolators are made of elastomeric material that can deform and recover, providing the necessary degrees of freedom without direct mechanical contact between moving parts, thereby eliminating wear and friction issues in dusty environments.
Solution Approach 2:
The patent changes the physical state and properties of the isolator material by using elastomeric compounds with specific durometer ratings (e.g., 30-70 Shore A). This material selection allows the isolator to provide both horizontal compliance and vertical support, achieving multiple degrees of freedom through material properties rather than complex mechanical mechanisms.
2Ease of operation
If conventional seat suspension systems focus only on vertical oscillation attenuation, then the system remains simple and cost-effective, but operator comfort is reduced due to unaddressed horizontal oscillations
Solution Approach 1:
The elastomeric isolators are designed to perform multiple functions simultaneously: they provide vertical load support, attenuate vertical oscillations, and allow horizontal movement to reduce horizontal vibrations. This multi-functionality is achieved through the inherent properties of the elastomeric material and its geometric configuration, eliminating the need for separate mechanisms for each function.
Solution Approach 2:
The isolators are designed with non-uniform cross-sectional areas along their length, with larger cross-sections at the ends for attachment and smaller cross-sections in the middle. This local variation in geometry optimizes the stiffness distribution, providing appropriate support and compliance in different directions while maintaining a simple single-piece structure.
3Ease of operation
If the radial stiffness of the isolation system is increased to reduce horizontal oscillations, then operator comfort improves, but the system becomes less compliant and may transmit more shock loads
Solution Approach 1:
The isolators are designed with asymmetric stiffness characteristics, having different stiffness values in radial (horizontal) and axial (vertical) directions. The radial stiffness is optimized to be lower (100-300 lbf/in) to allow horizontal movement and attenuate horizontal oscillations, while the axial stiffness is higher to support vertical loads and the operator's weight effectively.
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 system effectively isolates operators from horizontal oscillations between 5 Hz to 20 Hz, improving comfort by providing comprehensive vibration damping and reducing wear and friction problems, while maintaining structural integrity and simplicity.
Implementation Method 1
each isolator includes a tapered elastomeric tubular body
Implementation Method 2
attenuate or dissipate low frequency oscillations and shock loads
Data Source
AI summary
An isolation system for use in damping and isolating low frequency oscillations and shock loads between two members. An exemplary application is a seat isolation system for use with a vehicle such as a lawn mower. The seat isolation system may include two or more isolators interposed between a chassis of the vehicle, and a seat (e.g., operator's seat). The isolators may permit attenuation of shock or low frequency oscillation inputs via damping and isolation in both vertical and horizontal (fore-and-aft and side-to-side) directions. In some embodiments, the isolators include an elastomeric element that provides the seat with six degrees of freedom.