Fail-Safe Brake Valve Unit for Power-Loss Deceleration
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Solution Overview
Problem
Existing electronically controllable pneumatic braking systems in utility vehicles face challenges in ensuring safe deceleration when both the primary and redundant braking systems fail, leading to a risk of uncontrolled vehicle movement.
Innovation Solution
A fail-safety valve unit with monostable failure brake valves connected in series, controlled by independent control units, automatically switches to an open position in the absence of electrical power, providing a failure brake pressure to ensure safe deceleration, and includes features like a bistable valve, pressure sensor, and redundant compressed air supplies to enhance safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fully redundant braking systems are used to ensure safe deceleration in case of faults, then the reliability of the braking system is improved, but the device complexity increases
Solution Approach 1:
The fail-safety valve unit is pre-configured with multiple monostable failure brake valves connected in series that automatically open upon loss of electrical power, providing preliminary preparation for fault conditions without requiring complex real-time decision-making systems
Solution Approach 2:
The fail-safety function is extracted as a separate, independent valve unit with its own pneumatic circuit and control logic, disconnected from the main electronic braking control, thereby simplifying the overall system architecture while maintaining reliability
2Reliability
If multiple monostable failure brake valves connected in series are used to provide fail-safety pressure, then the reliability in multiple fault scenarios is improved, but the device complexity increases
Solution Approach 1:
The loss of electrical power, which is normally a harmful failure condition, is converted into a beneficial trigger that automatically opens the monostable failure brake valves and activates the fail-safety pneumatic pressure to maintain braking capability
Solution Approach 2:
The failure brake function is segmented into multiple independent monostable valves connected in series, each controlled by independent control units, allowing distributed fault tolerance without requiring a single complex control mechanism
3Reliability
If independent control units with independent power supplies are used, then the redundancy and reliability are improved, but the device complexity and cost increase
Solution Approach 1:
Each control unit is assigned to control a specific failure brake valve with its own power supply, creating localized independent control zones that provide redundancy without requiring full system-wide duplication of complex control logic
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 ensures safe vehicle deceleration even in multiple fault scenarios by providing a failure brake pressure, maintaining the braked state, and enhancing redundancy through independent control and air supply, thus preventing accidents.
Implementation Method 1
both the first failure brake valve (40) and the second failure brake valve (60) automatically switch into an open position (40A, 60A) owing to an elastic restoring force generated by a respective restoring spring (41, 61)
Implementation Method 2
The fail-safety valve unit (1) furthermore has a pressure sensor (33), in particular for checking the plausibility of the function of the failure brake valves (40, 60)
Data Source
AI summary
A fail-safety valve unit is for a failure braking function of a pneumatic braking system for a vehicle. The fail-safety valve unit has a first and a second failure brake valve configured as monostable valves, and a main line which pneumatically connects a main port, which provides a first pressure, and a failure port. The first and second failure brake valves are connected pneumatically in series in the main line. The first and the second failure brake valves are controllable by different control units. The failure brake valves are open in an open position when not actuated such that the first pressure prevailing at the main port is provided as a failure brake pressure at the failure port such that, in a fault situation, in an electrical failure, and/or in a diagnostic situation, a failure braking operation is triggered via provision of the failure brake pressure at the failure port.