Rail Axle Guiding Assembly with Load-Dependent Hydraulic Pressurizing
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Solution Overview
Problem
Existing wheel axle guiding assemblies for rail vehicles are significantly impacted by temperature changes and leakage, leading to reduced dynamic stiffness and cavitation issues due to the lack of thermal contraction compensation and inadequate pressure maintenance in hydraulic systems.
Innovation Solution
A wheel axle guiding assembly with a hydro-mechanical guiding system featuring load-dependent pressurizing means, including elastomeric bodies forming deformable walls within variable volume hydraulic chambers, which maintain pressure through vertical loads and prevent cavitation, ensuring stability even at low temperatures and in case of leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If hydraulic fluid is used in variable volume chambers for fore-and-aft movement, then smooth passive steering and active steering are enabled, but thermal contraction at low temperature causes cavitation and reduces dynamic stiffness
Solution Approach 1:
The patent changes the physical parameters of the hydraulic system by introducing a compressible gas cushion (air chamber) that compensates for thermal contraction of the hydraulic fluid. The gas volume and pressure are adjusted to maintain adequate fluid pressure in the variable volume chambers during cold temperature operation, preventing cavitation while preserving the steering functionality.
Solution Approach 2:
The patent introduces an intermediary air chamber that acts as a buffer between the hydraulic fluid and the external environment. This air chamber absorbs the effects of thermal contraction and provides a compensating pressure source, mediating between the hydraulic system and temperature variations to prevent direct cavitation damage.
2Ease of operation
If hydraulic fluid is used in the guiding assembly, then fore-and-aft movement is enabled, but leakage results in significant reduction of longitudinal stiffness
Solution Approach 1:
The air chamber serves as an intermediary backup system that maintains pressure support in the hydraulic chambers even when leakage occurs. The compressible gas provides a secondary pressure source that compensates for fluid loss, maintaining adequate stiffness and preventing complete system failure during leakage events.
Solution Approach 2:
The patent implements beforehand cushioning by pre-filling the air chamber with compressed gas that can immediately compensate for potential leakage. This preparatory measure ensures that even if hydraulic fluid leaks, the air cushion maintains sufficient pressure to preserve longitudinal stiffness and prevent sudden loss of control.
3Adaptability or versatility
If variable volume hydraulic chambers are used for steering, then passive and active steering functionality is achieved, but temperature changes cause volume reduction and pressure loss
Solution Approach 1:
The patent compensates for temperature-induced parameter changes by introducing a gas-filled chamber whose pressure and volume characteristics change with temperature in the opposite direction to the hydraulic fluid. This counterbalancing parameter change maintains adequate pressure in the variable volume chambers across different temperature conditions, ensuring reliable steering operation.
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 enhanced stability and reduced impact from temperature fluctuations and leakage, maintaining dynamic stiffness and preventing cavitation, ensuring reliable fore-and-aft movement and steering functionality.
Implementation Method 1
The hydro-mechanical guiding assembly comprises a set of one or more elastomeric bodies, which form deformable walls of the first variable volume hydraulic chamber and second variable volume hydraulic chamber and constitute the load-dependent pressurising means
Implementation Method 2
an increase in a vertical load applied by the support assembly on the axle box assembly in the standard operational position of the wheel axle guiding assembly results in a pressure increase in the first variable volume hydraulic chamber and second variable volume hydraulic chamber
Data Source
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AI summary
A wheel axle guiding assembly (31) for a running gear (10) of a rail vehicle, comprises: an axle box assembly (30), a support assembly (24) and a hydro-mechanical guiding assembly (26) fixed to the axle box assembly (30) and to the support assembly (24) to allow a fore-and-aft movement of the axle box assembly (30) relative to the support assembly (24). The hydro-mechanical guiding assembly (26) comprises: a first variable volume hydraulic chamber (38A) and a second variable volume hydraulic chamber (38B) between the support assembly (24) and the axle box assembly (30) such that a movement of the axle box assembly (30) relative to the support assembly (24) in the steering direction (300) results in a reduction of an internal volume of the one of the first and second variable volume hydraulic chambers (38A, 38B) and a corresponding increase of an internal volume of the other of the first and second variable volume hydraulic chambers (38A, 38B). The hydro-mechanical guiding assembly (26) further comprises load-dependent pressurising means (42) such that an increase in a vertical load applied by the support assembly (24) on the axle box assembly (30) results in an increase of pressure into the first variable volume hydraulic chamber (38A) and second variable volume hydraulic chamber (38B).