Vehicle Suspension with Series Gas Spring for Roll Control
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Solution Overview
Problem
Existing vehicle suspensions face challenges in balancing comfort and roll reduction across various driving conditions and road types, with current solutions being either expensive, complex, or lacking versatility and adaptability.
Innovation Solution
A suspension system that combines a coil spring with a gas spring, where the gas spring is operatively coupled in series and fluidically independent from the damper, allowing for adjustable spring modulus based on piston displacement, initial volume, and pressure, enabling a wide range of force-displacement characteristics without replacing parts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a coil spring with high spring modulus is used to reduce roll motion, then roll reduction is improved, but comfort deteriorates due to high transmitted loads
Solution Approach 1:
The patent applies a progressive spring modulus that dynamically changes based on piston position. The spring modulus increases as the piston travels further from its initial position, allowing the suspension to be soft at small deflections for comfort and stiff at large deflections for roll control. This is achieved through the geometric relationship between the piston rod, lever arm, and spring attachment points, creating a nonlinear force-displacement characteristic.
Solution Approach 2:
The patent changes the spring modulus parameter as a function of piston displacement. By designing the linkage geometry such that the effective spring constant varies with position, the system transitions from a low-stiffness state (absorbing bumps) to a high-stiffness state (resisting roll). This parameter change is achieved through the mechanical advantage variation in the lever arm system as the piston moves.
2Object-affected harmful factors
If a coil spring with low spring modulus is used to improve comfort, then comfort is improved, but roll motion deteriorates due to excessive roll
Solution Approach 1:
The progressive spring modulus dynamically adapts to the operating condition. During normal riding with small suspensions deflections, the spring operates in its soft region providing comfort. During cornering or when large deflections occur, the spring progressively stiffens to limit roll motion, thus the same spring structure addresses both contradictory requirements at different operating points.
Solution Approach 2:
The spring modulus parameter is designed to change with piston position, transitioning from low values (for comfort) to high values (for roll control). This is achieved through the geometric configuration of the linkage system where the mechanical advantage and effective leverage change as the piston moves from its initial position, creating a progressive spring characteristic.
3Adaptability or versatility
If non-linear spring elements such as air springs are used to achieve progressive spring modulus, then versatility is improved, but device complexity deteriorates
Solution Approach 1:
The patent uses a pneumatic spring (air spring) to provide the progressive spring modulus characteristic. The air spring's natural nonlinear pressure-volume relationship creates the desired progressive stiffness without complex mechanical linkages. By enclosing a fixed volume of air and allowing it to compress and expand, the system achieves variable spring modulus that increases with deflection, combining versatility with relative simplicity.
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
This hybrid system provides high comfort and reduced roll, with adjustable spring characteristics and ground clearance, offering simplicity, reliability, and versatility, while maintaining the reliability of a coil spring in case of gas leakage.
Implementation Method 1
at least one gas spring operatively coupled in series to said at least one spring element and acting for at least part of the stroke of said piston relative to said cylinder
Implementation Method 2
a fluidic damper that is constrained between at least the wheel and the frame of the vehicle and provided with a cylinder and a piston sliding within said cylinder
Data Source
Figure 1~2
Figure 3~4
AI summary
Suspension (1) for a wheeled vehicle comprising at least one fluidic damper (2) constrained between at least one wheel and the frame of said vehicle and provided with a cylinder (3) and a piston (4) sliding within said cylinder, at least one spring element (5) coupleable to said fluidic damper for the transmission of loads between said at least one wheel and said frame when the position of said piston with respect to said cylinder changes, and means (6) for changing the law of transmission of loads of said at least one spring element (5) when the position of said piston relative to said cylinder changes, characterized in that said means for changing the law of transmission of loads comprise at least one gas spring (7) operatively coupled in series to said at least one spring element (5) and acting for at least part of the stroke of said piston relative to said cylinder, said at least one gas spring being fluidically independent from said at least one fluidic damper.