Interconnected Suspension Hydraulics for Separate Pitch and Roll Tuning
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Solution Overview
Problem
Current vehicle suspension systems face challenges in achieving attenuated suspension stiffness while maintaining low service cost, weight, and packageability across various suspension architectures, and in independently controlling pitch and roll stiffness.
Innovation Solution
A configurable interconnected suspension system incorporating hydraulic cylinders, valve assemblies, and accumulators, with piston-cylinder assemblies that utilize springs and hardstops to manage hydraulic fluid flow and pressure differentials across chambers, allowing for adjustable stiffness and damping in response to pitch, roll, and warp events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional suspension systems are used, then basic suspension function is provided, but suspension stiffness cannot be independently controlled for pitch and roll
Solution Approach 1:
The suspension system is divided into four independent hydraulic cylinders, each with its own piston-cylinder assembly and accumulator. This segmentation allows independent control of each wheel's suspension characteristics, enabling separate adjustment of pitch and roll stiffness without requiring a completely complex integrated system.
Solution Approach 2:
Each hydraulic cylinder serves multiple functions: it provides suspension support, damping, and acts as part of the interconnected system for controlling both pitch and roll movements. The valve assembly also performs multiple functions by controlling hydraulic fluid flow to achieve various suspension modes simultaneously.
2Ease of operation
If attenuated suspension stiffness is achieved, then vehicle comfort and performance are improved, but service cost and maintenance requirements increase
Solution Approach 1:
The accumulators in each hydraulic cylinder automatically maintain system pressure and compensate for fluid volume changes during compression and rebound cycles. This self-regulating mechanism reduces the need for frequent manual adjustments and interventions, lowering maintenance requirements despite the advanced functionality.
Solution Approach 2:
The system uses hydraulic fluid and accumulators to provide automatic stiffness attenuation and damping control. This passive hydraulic approach eliminates the need for complex electronic control systems and active actuators, reducing service cost while maintaining advanced suspension characteristics.
3Adaptability or versatility
If interconnected hydraulic system is implemented, then independent stiffness tuning is enabled, but system weight increases
Solution Approach 1:
The system merges the functions of multiple hydraulic circuits into an interconnected arrangement where four hydraulic cylinders share common accumulators and valve control. This consolidation achieves independent stiffness tuning capability while avoiding the weight penalty of completely separate systems for each function.
4Force
If multiple accumulators are used as spring elements, then suspension stiffness is attenuated, but packageability is reduced
Solution Approach 1:
The accumulators are integrated within the existing suspension assembly structure, nesting the spring elements inside or alongside the hydraulic cylinders rather than adding separate external components. This approach achieves stiffness attenuation while minimizing additional package space requirements.
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 achieves reduced suspension stiffness for improved vehicle performance and comfort, with low maintenance costs and weight, while enabling independent tuning of pitch and roll stiffness for enhanced driving dynamics.
Implementation Method 1
a spring coupled to the piston and configured to apply a force on the piston based on a displacement (e.g., an axial position) of the piston in the cylinder
Implementation Method 2
The plurality of accumulators act as spring elements for storing and releasing the hydraulic fluid as the plurality of hydraulic cylinders compress and rebound
Implementation Method 3
causing, in response to pitch (e.g., a pitch event), displacement of a piston of a piston-cylinder assembly through a full stroke based on a pressure differential of hydraulic fluid across the piston-cylinder assembly
Implementation Method 4
causing, in response to a roll event, a warp event, or a heave event, a displacement of the piston through at most a partial stroke based on pressure of the hydraulic fluid on either side of the piston
Data Source
AI summary
A vehicle includes system for providing configurable stiffness characteristics. The system includes a cylinder having a first chamber and a second chamber, and a piston arranged between the first chamber and a second chamber. The first chamber is coupled to a first rebound volume and a first compression volume of a plurality of hydraulic cylinders, each corresponding to a respective wheel of a vehicle. The second chamber is coupled to a second rebound volume and a second compression volume of the plurality of hydraulic cylinders.