Hydropneumatic Suspension Cylinder With Integrated Air Spring
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Solution Overview
Problem
Existing hydropneumatic suspension systems for vehicle wheel assemblies struggle to effectively distribute load and absorb impacts at varying speeds and loads, particularly due to the limitations of hydraulic accumulators set to predefined calibration values, leading to inefficient dynamic responses and potential overloads.
Innovation Solution
A hydropneumatic system with integrated air springs in the cylinders that adapt to load and road conditions, using a piston element to vary chamber volumes and pressure distribution without relying on external accumulators, ensuring consistent damping across different loads and speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If parachute valves are used to block oil flow in case of breakage, then safety is improved, but the dynamic response to road unevenness deteriorates at high speeds
Solution Approach 1:
The parachute valve is modified to include a speed-sensitive component that changes the valve's flow characteristics based on vehicle speed. At low speeds, the valve blocks oil flow to prevent suspension collapse. At high speeds, the valve allows controlled oil flow to maintain suspension compliance and dynamic response to road unevenness.
2Reliability
If additional hydraulic accumulators are added to absorb impacts, then impact absorption is improved, but device complexity and cost increase
Solution Approach 1:
The air spring chamber is integrated directly into the existing hydraulic cylinder structure, combining the functions of hydraulic suspension and pneumatic impact absorption into a single component. This eliminates the need for separate hydraulic accumulators while maintaining impact absorption capability.
Solution Approach 2:
The hydraulic cylinder is designed to perform multiple functions: supporting static vehicle weight, absorbing dynamic impacts, and providing suspension compliance. The integrated air spring enables the cylinder to handle both gradual load changes and sudden impacts without requiring additional specialized components.
3Loss of time
If the parachute valve activation threshold is lowered to respond faster, then response time is improved, but false activation during normal operation increases
Solution Approach 1:
A speed sensing mechanism provides feedback to the parachute valve control system. The valve activation threshold is dynamically adjusted based on real-time vehicle speed information, allowing fast response at high speeds while preventing false activation during normal low-speed operation.
Solution Approach 2:
The parachute valve transitions from a static fixed-threshold design to a dynamic variable-threshold design that adapts its activation characteristics based on operating conditions. This allows the system to optimize between response time and false activation prevention depending on vehicle speed.
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 provides a compact, cost-effective solution that automatically adjusts to load and speed variations, effectively distributing pressure and absorbing impacts without the need for additional hydraulic components, maintaining consistent performance regardless of vehicle dynamics.
Implementation Method 1
the air spring's stiffness adjusts to the load and absorbs road unevenness
Implementation Method 2
using a piston element to manage pressure and distribute load uniformly across suspensions
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
A hydropneumatic system (51) for suspensions of vehicle wheel assemblies is provided, for each suspension, with a respective hydropneumatic cylinder (1) having a first and a second body (10,11), which can move axially relative to each other and define respective chambers (14,15), axially separated from each other via a piston element (30); the latter is coupled in a fluid-tight manner to the second body (11) and floats between two stroke end positions in response to the pressures in the two chambers (14,15); the two chambers (14,15) of each hydropneumatic cylinder (1) communicate respectively with a hydraulic supply line (52) and with a pneumatic supply line (57); the system (51) further has a pressurization device which sets the pressure in the pneumatic supply line (57) to a value at least equal to the pressure in the hydraulic supply line (52).