Emergency Rail Brake Pressure Control Under Power Loss
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Solution Overview
Problem
Existing rail vehicle brake systems face issues with variations in brake-pad friction and mechanical factors leading to under or over braking, particularly during emergency braking, due to inaccuracies in brake force calculation and actuation.
Innovation Solution
A brake system with a vent valve arrangement that sets brake force above calculated levels to offset mechanical variations, using a microcontroller for pressure regulation and monitoring to ensure minimum emergency brake pressure and prevent over-braking, with a remote release valve and pressure controller to manage brake cylinder pressure independently, and SIL3 electronics for high-integrity operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If brake force is set according to calculated levels, then brake system simplicity is maintained, but brake pressure control precision deteriorates due to variations in brake-pad friction and mechanical factors
Solution Approach 1:
The patent implements a feedback control system where a microcontroller continuously monitors brake cylinder pressure via a pressure sensor and adjusts the vent valve actuation accordingly. During emergency braking, the system monitors pressure and vents air from the brake cylinder when pressure exceeds the target level, ensuring precise pressure control despite variations in brake-pad friction and mechanical factors. This closed-loop feedback mechanism resolves the contradiction by maintaining high pressure control precision without requiring excessive system complexity.
Solution Approach 2:
The brake system incorporates self-regulating features where the microcontroller automatically manages pressure control based on real-time sensor data. The system self-adjusts vent valve actuation to maintain target pressure levels during emergency braking, eliminating the need for complex external control mechanisms while achieving precise pressure control through autonomous monitoring and adjustment.
2Reliability
If available brake pressure is set for maximum deceleration, then emergency braking capability is improved, but risk of over-braking increases due to mechanical variations
Solution Approach 1:
The patent applies preliminary anti-action by pre-configuring the control algorithm to anticipate and counteract potential over-braking conditions. During emergency braking, the microcontroller continuously compares actual pressure against target pressure levels and proactively vents excess pressure before it can cause harmful over-braking effects. This preventive approach maintains high emergency braking reliability while eliminating over-braking risks through advance pressure management.
Solution Approach 2:
The real-time pressure monitoring and feedback control system detects pressure deviations and immediately adjusts vent valve actuation to prevent over-braking. The feedback loop ensures that brake pressure remains within safe operational limits while maintaining the high deceleration capability needed for reliable emergency braking, thus resolving the contradiction between braking reliability and over-braking prevention.
3Measurement precision
If brake pressure is regulated below available pressure for service braking, then service braking precision is improved, but emergency braking response time deteriorates
Solution Approach 1:
The patent implements dynamic pressure control where the system adapts its regulation strategy based on the braking mode. During service braking, the microcontroller regulates pressure below available pressure for precise control. Upon detecting an emergency braking condition, the system dynamically switches to a different control mode where it rapidly applies full available pressure and then immediately activates feedback control to manage pressure levels. This dynamic adaptation resolves the contradiction by optimizing for precision during service braking while minimizing response time during emergency braking.
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 precise control of brake pressures, reducing the likelihood of under or over braking by maintaining a consistent deceleration rate and ensuring reliable emergency braking performance even in power loss scenarios, while preventing prolonged under-pressure conditions and enabling safe operation during service and emergency braking.
Implementation Method 1
an emergency brake comprising a solenoid working on the principle of de-energizing to close, which solenoid in normal operation is powered and held in the open position
Data Source
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AI summary
An electropneumatic rail brake system configured to provide emergency braking comprising an emergency magnet valve which controls air flow into an emergency regulator valve, which valve has an emergency back-up chamber. The emergency regulator provides an output pressure nominally equal to the variable load pressure and no lower than the tare back-up. The magnet valve is closed when energised and when de-energised, pressure is allowed into the emergency back-up chamber, Regulation of the brake cylinder pressure continues during an emergency application such that the brake cylinder pressure applied during an emergency stop does not drop below a predetermined level. In the event of power-loss during an emergency brake stop, the nominal emergency brake pressure is applied to the brake cylinders.