Variable Spring Rate Shock Absorber With Segmented Gas Chambers
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Solution Overview
Problem
Existing vehicle suspension systems with gas springs face challenges in maintaining a linear spring rate over a wide range of travel, especially on uneven surfaces and in vehicles with non-vertical axes, as traditional designs rely on gravity and are not adaptable for complex shock absorbers with fluidly isolated dampers.
Innovation Solution
A shock absorber with multiple gas chambers and a fluid isolated damper that allows for adjustable spring and damping rates, using a mechanical actuator to open communication between chambers and a Schrader-type valve for equal pressure filling, enabling a variable spring rate and damping system that maintains linearity and reduces the formation of emulsions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single gas chamber is used in a shock absorber, then the structure is simple, but the spring rate becomes exponential and non-linear beyond mid-range compression
Solution Approach 1:
The gas spring is divided into multiple separate gas chambers (first gas chamber and second gas chamber) that operate sequentially. The first chamber provides linear spring rate during initial compression, while the second chamber activates later to extend the linear range, preventing the exponential stiffening that occurs in single-chamber designs.
Solution Approach 2:
The system dynamically transitions between different gas chambers based on compression level. A communication valve selectively opens or closes fluid pathways between chambers, allowing the spring to adapt its characteristics during operation - using the first chamber for small displacements and the second chamber for larger displacements to maintain linearity.
2Device complexity
If gravity-based valve operation is used to open communication between chambers, then the mechanism is simple, but it fails on uneven surfaces and in vehicles with non-vertical axes
Solution Approach 1:
The gravity-based mechanical valve operation is replaced with a pressure differential-based system. The communication valve responds to pressure differences between chambers rather than gravitational force, allowing reliable operation regardless of vehicle orientation or surface unevenness. The valve opens when pressure in the first chamber exceeds pressure in the second chamber by a threshold amount.
Solution Approach 2:
The system uses its own operating parameters (pressure differential during compression) to control valve operation. The compression process itself generates the pressure difference needed to open the communication valve, eliminating the need for external actuation or gravity-dependent mechanisms.
3Force
If higher initial pressure is set in the gas spring, then the vehicle handling improves, but the shock absorber becomes prematurely stiff
Solution Approach 1:
The total gas spring force is segmented across multiple chambers with different pressure levels. The first chamber operates at higher initial pressure to provide strong force for small displacements (improving handling), while the second chamber operates at lower pressure to provide gradual force increase for larger displacements (extending usable travel range).
Solution Approach 2:
Different regions of the compression stroke have different pressure characteristics. The initial compression phase uses high pressure from the first chamber for responsive handling, while the later compression phase transitions to the lower pressure second chamber to prevent premature stiffness and maintain comfort over larger travel distances.
4Quantity of substance
If separate filling of multiple gas chambers is performed, then each chamber can be optimized independently, but the filling process becomes complex
Solution Approach 1:
The fill valve assembly performs multiple functions: it can fill the first gas chamber independently, fill the second gas chamber independently, and provide a common filling port for both chambers. This universal design allows flexible filling options - technicians can choose to fill chambers separately for optimization or use the common port for simpler operation, eliminating the need for complex separate filling mechanisms.
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 provides a shock absorber with a substantially linear spring rate over a greater range of travel, improving vehicle ride and handling by allowing higher initial pressure settings without premature stiffness, and reducing space requirements with an integrated damper/spring assembly.
Implementation Method 1
a first gas spring chamber (165) and a second gas spring chamber (170)
Implementation Method 2
a viscous damping mechanism (210) integrated within the shock absorber
Data Source
AI summary
Embodiments of the invention generally relate to methods and apparatus for use in vehicle suspension. Particular embodiments of the invention relate to methods and apparatus useful for variable spring rate and/or variable damping rate vehicle suspension. In one embodiment, a shock absorber for a vehicle includes a gas spring having first and second gas chambers. The first chamber is utilized during a first travel portion of the shock absorber and the first and second chambers are both utilized during a second portion of travel. The shock absorber further includes a fluid isolated damper for regulating the speed of travel throughout both portions of travel.