Control Valve for Rail Vehicle Brakes Using Constant Pressure Change
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Solution Overview
Problem
Conventional control valves for rail vehicle compressed air brakes rely on a constant pilot volume flow, making braking and release times dependent on the size of the pilot control volume, which can vary and is difficult to maintain uniformly across different rail vehicles.
Innovation Solution
A control valve design featuring a pneumatic pressure comparison membrane and a 2x4/3-way valve for variable flow throttling and switching, ensuring constant pressure changes during compressed air supply and venting, independent of the pilot volume, using a 2x4/3-way valve to manage flow and pressure changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a constant pilot volume flow is used in conventional control valves, then the braking and release times are determined by the pilot control volume size, but the times become dependent on and difficult to maintain uniformly across different rail vehicles
Solution Approach 1:
The patent changes the control parameter from constant volume flow to constant pressure change. The device for generating braking and release times is designed to produce a constant pressure change (Δp/Δt = constant) instead of a constant volume flow, making the braking and release times independent of the pilot control volume size while maintaining uniformity across different rail vehicle configurations
Solution Approach 2:
The patent replaces the conventional mechanical/volumetric flow control system with a pressure-based control system. Instead of relying on fixed volume flows through nozzles, the invention uses a device that actively maintains constant pressure change rates, substituting the passive volumetric approach with an active pressure regulation approach
2Adaptability or versatility
If the pilot control volume is varied across different rail vehicle configurations, then adaptability to different vehicles is improved, but maintaining uniform braking and release times becomes difficult
Solution Approach 1:
The patent decouples the relationship between pilot volume and braking/release times by changing from constant volume flow control to constant pressure change control. This allows the pilot volume to vary across different rail vehicle configurations while the device maintains uniform braking and release times through its constant pressure change characteristic
3Manufacturing precision
If precise pilot volume maintenance is required to achieve uniform braking times, then timing uniformity is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent replaces the complex requirement for precise pilot volume maintenance with a simpler pressure-based control mechanism. The device for generating braking and release times directly controls pressure change rates, eliminating the need for precise volumetric dimensions and reducing manufacturing complexity while maintaining timing uniformity
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 design allows for uniform braking and release times regardless of the pilot volume size, simplifying manufacturing and ensuring consistent performance across different rail vehicle configurations, avoiding the need for precise pilot volume maintenance and preventing asymptotic pressure equalization.
Implementation Method 1
a pneumatic pressure comparison membrane for comparing the pilot control pressure with a reference pressure and for generating a proportional pressure change
Implementation Method 2
a 2x4/3-way valve for controlling a compressed air supply and a venting of the pilot control circuit, with which valve parts integrated in the valve can be actuated by the pressure comparison membrane into switching positions
Data Source
Figure 1~2
AI summary
The invention relates to a control valve for an indirectly acting compressed air brake of a rail vehicle, comprising a pneumatic relay valve (4) for controlling a brake cylinder pressure (C) via a pilot circuit (1) to generate a time-defined pilot pressure (cv) for the proportional control of the relay valve (4), wherein a device upstream of the pilot circuit (1) is provided for generating the braking and release times of the compressed air brake, wherein the device for generating uniform braking and release times of the compressed air brake has means (T) for realizing a volume flow with constant pressure change for the compressed air supply (R) as well as the venting (0) of the pilot circuit (1).