Brake Circuit Safety Gate for Fault-Tolerant Pressure Isolation
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Solution Overview
Problem
Current brake systems face challenges in maintaining safety and preventing failure, especially in scenarios involving single and double faults, which can lead to inadequate braking deceleration and total system failure, particularly in advanced vehicle automation levels where high reliability is required.
Innovation Solution
A brake system design featuring a reduced number of valves, including a safety gate for selective isolation and connection of brake circuits, a single pressure supply device, and diagnostic capabilities to identify faults, allowing for precise pressure control and redundancy to ensure high fail safety and sufficient braking performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a reduced number of valves is used in the brake system, then the structural volume and device complexity are reduced, but the reliability and fail safety may be compromised
Solution Approach 1:
The switching valve is designed to perform multiple functions: it acts as a circuit isolation valve for safety gate functionality, a switching valve for connecting/disconnecting wheel brakes to brake circuits, and a diagnostic valve for fault detection. This multi-functionality reduces the total number of valves needed in the system while maintaining reliability through integrated safety and diagnostic capabilities.
Solution Approach 2:
The patent combines the safety gate isolation function, wheel brake switching function, and diagnostic function into a single integrated valve system. By merging these previously separate functions into one valve, the device complexity is reduced while the reliability is maintained through the valve's ability to handle multiple operational modes and safety requirements.
2Reliability
If diagnostic capabilities are added to identify faults, then the reliability and safety are improved, but the device complexity increases
Solution Approach 1:
The switching valve incorporates diagnostic functionality as an integrated feature rather than a separate system. The valve can detect faults in brake circuits, wheel brakes, and itself through its existing operational mechanisms, providing diagnostic capabilities without adding separate diagnostic hardware and thus minimizing additional complexity.
Solution Approach 2:
The valve performs self-diagnostics by monitoring its own operational state and the state of connected brake circuits. The diagnostic function utilizes the valve's existing sensors and control mechanisms to detect faults, eliminating the need for external diagnostic systems and reducing overall device complexity while improving reliability.
3Reliability
If redundancy is implemented to ensure high fail safety, then the reliability is improved, but the structural volume and device complexity increase
Solution Approach 1:
The switching valve provides redundant safety functionality by integrating circuit isolation capabilities directly into the valve structure. This allows the same component to serve both as a control valve and as a safety isolation mechanism, achieving redundancy without adding separate isolation valves and thus avoiding increased device complexity.
Solution Approach 2:
The patent merges the safety isolation function with the primary switching function in a single valve assembly. By combining these functions, the system achieves the redundancy needed for high fail safety while avoiding the structural volume and complexity that would result from adding separate redundant components.
4Device complexity
If a single pressure supply device is used instead of multiple devices, then the structural volume and cost are reduced, but the reliability and ability to handle single and double faults are compromised
Solution Approach 1:
The single pressure supply device is designed to work with the multi-functional switching valve that can isolate and protect different brake circuits. This allows the single pressure supply to serve multiple brake circuits while maintaining fault tolerance through the protective isolation capabilities integrated into the valve system, achieving reliability without needing multiple pressure supply devices.
Solution Approach 2:
The switching valve acts as an intermediary between the single pressure supply device and multiple brake circuits. It provides the necessary isolation and protection functions that would otherwise require multiple pressure supply devices, enabling a single pressure supply to reliably serve multiple circuits while maintaining fault tolerance.
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 achieves a high level of fail safety, reduced structural volume, and low probability of failure, maintaining sufficient braking deceleration even in fault conditions, with enhanced diagnostic capabilities and cost-effectiveness.
Implementation Method 1
a pressure build-up is performed or can be performed in both brake circuits by means of the pressure supply device
Implementation Method 2
at least one circuit isolation valve, which is in particular open when electrically deenergized, is provided and serves for selectively shutting off and opening up a hydraulic connecting line that connects the two brake circuits
Implementation Method 3
each hydraulically acting wheel brake is connectable by means of a respectively assigned switching valve to its brake circuit or to the brake circuit line thereof, wherein the pressure build-up and the pressure reduction in the respective wheel brake is performed via the respectively assigned switching valve
Data Source
AI summary
A brake system includes two brake circuits having brake circuit lines for two vehicle axles and at least one hydraulic wheel brake in each brake circuit. Each wheel brake is connectable to a corresponding brake circuit or brake circuit line via a paired switch valve for pressure build-up and release in the wheel brake using a pressure supply device that can build up pressure in both brake circuits. At least one circuit separating valve blocks or releases a hydraulic connection line connecting the two brake circuits. At least one outlet valve connects an accumulator container to at least one brake circuit to release pressure. A master cylinder having only one working chamber is actuable by a brake pedal. The working chamber is connectable to the brake circuit line of a brake circuit. A switch valve is used to close or release the hydraulic line.