Railway Braking Control Architecture for SIL3 Additional Functions
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Solution Overview
Problem
Current railway braking systems face challenges in maintaining high safety integrity levels for additional braking functions, such as the Holding Brake and Distributor Emulation, which are typically developed at SIL≤2 levels, leading to potential malfunctions and increased development, certification, and maintenance costs when trying to elevate them to SIL≥3 levels.
Innovation Solution
A braking system architecture that separates emergency and service braking control units, allowing the emergency braking control unit to determine additional pressure values for additional braking functions and transmit them to the service braking control unit, ensuring that these functions operate at the same SIL≥3 level as the emergency braking control unit, thereby simplifying the system and reducing complexity and costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional braking functions are developed at SIL≤2 levels, then development and certification costs are reduced, but safety integrity level is insufficient leading to potential malfunctions
Solution Approach 1:
The patent merges additional braking functions (Holding Brake, Distributor Emulation) into the emergency braking control unit which operates at SIL≥3 level. This consolidation allows these functions to inherit the high safety integrity level without requiring separate SIL≤2 development, thereby improving reliability while avoiding the need for costly separate certification processes.
Solution Approach 2:
The emergency braking control unit is designed to perform multiple functions including both emergency braking and additional braking functions (Holding Brake, Distributor Emulation). By making the control unit universal and multi-functional, the system eliminates the need for separate control units for different braking modes, reducing overall system complexity and certification costs while maintaining high safety integrity across all functions.
2Reliability
If additional braking functions are developed at SIL≥3 levels, then safety integrity level is improved, but development, certification, and maintenance costs increase
Solution Approach 1:
The patent combines multiple braking functions under a single emergency braking control unit operating at SIL≥3 level. This merging approach improves safety integrity for additional braking functions while actually reducing system complexity by eliminating the need for separate control units and their interconnections, thereby avoiding the complexity that would arise from multiple independently certified systems.
Solution Approach 2:
The emergency braking control unit is designed as a universal controller that handles both emergency braking and additional braking functions (Holding Brake, Distributor Emulation). This multi-functionality reduces device complexity by consolidating control logic into a single unit rather than requiring multiple specialized control units, while maintaining high safety integrity across all functions.
3Ease of manufacture
If additional braking functions are developed at SIL≤2 levels, then development costs are reduced, but potential malfunctions increase
Solution Approach 1:
The patent merges additional braking functions into the emergency braking control unit that operates at SIL≥3 level. This consolidation ensures that functions like Holding Brake and Distributor Emulation inherit the high safety integrity level, thereby eliminating malfunction risks associated with lower SIL levels while avoiding the need for separate expensive development and certification processes.
Solution Approach 2:
The emergency braking control unit is designed to universally handle multiple braking functions including emergency braking, Holding Brake, and Distributor Emulation. By making the control unit multi-functional and operating at SIL≥3 level, the system ensures high reliability across all functions without requiring separate development for each function, thereby reducing overall development costs while minimizing malfunction risks.
Data Source
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AI summary
Various embodiments of a braking system (500) for at least one bogie or railway vehicle comprising an emergency braking control unit (503) made according to a first safety integrity level and a service braking control unit (508) made according to a second safety integrity level lower than said first safety integrity level are described; the braking system (500) carrying out at least one additional braking function (550) at the same safety integrity level as the emergency braking control unit (503).