Brake Circuit Isolation With Pressure Accumulator Fail-Safe Braking
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Solution Overview
Problem
Existing braking systems face challenges in ensuring reliability and safety, particularly in scenarios involving single and double faults, which can lead to inadequate braking performance and increased failure probability, especially in higher levels of vehicle automation.
Innovation Solution
A braking system with two brake circuits, each connected via a switching valve, utilizing a single pressure supply device and circuit isolation valves to ensure redundancy and fault tolerance, allowing for controlled pressure build-up and reduction, and incorporating diagnostic capabilities to detect faults.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single pressure supply device is used to supply both brake circuits, then costs and device complexity are reduced, but reliability deteriorates because a failure of the pressure supply device causes both brake circuits to fail
Solution Approach 1:
The single pressure supply device is segmented into two independent pressure chambers (first pressure chamber and second pressure chamber) that can operate independently. Each chamber can supply pressure to one brake circuit separately, allowing the system to maintain partial braking function even if one chamber fails. This segmentation resolves the contradiction by reducing device complexity while maintaining reliability through independent operation of the chambers.
Solution Approach 2:
Different regions of the pressure supply device (first pressure chamber and second pressure chamber) are given different functional characteristics. Each chamber can be independently controlled and monitored, with local diagnostic capabilities. This allows the system to identify and isolate failures in one chamber without affecting the other, resolving the reliability concern while maintaining a single integrated device structure.
2Reliability
If circuit isolation valves are added to separate brake circuits for fault isolation, then reliability improves, but device complexity and installation space increase
Solution Approach 1:
The circuit isolation valves are merged with the pressure supply device structure, integrating the isolation function into the existing device rather than adding separate external components. The first and second circuit isolation valves are incorporated into the pressure supply device housing, reducing overall device complexity while maintaining the ability to isolate brake circuits for fault tolerance.
Solution Approach 2:
The pressure supply device serves multiple functions: it generates pressure, isolates circuits, and provides diagnostic capabilities all within a single integrated structure. The circuit isolation valves are designed to work in conjunction with the pressure chambers and diagnostic systems, allowing one component to perform multiple safety functions, thereby reducing the need for additional separate components.
3Reliability
If diagnostic functions are implemented to detect faults in the pressure supply device, then reliability improves through early fault detection, but device complexity increases
Solution Approach 1:
The pressure supply device performs self-diagnosis through integrated sensors and control units that continuously monitor pressure levels, chamber integrity, and valve operation. The system automatically detects faults such as pressure loss, leaks, or component failures and communicates these conditions to the vehicle's diagnostic system, enabling early fault detection without requiring external diagnostic equipment or complex external monitoring systems.
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 high fault tolerance, maintains sufficient braking pressure and deceleration, reduces costs and installation space, and provides robust diagnostic options, ensuring reliable braking performance even in the presence of faults.
Implementation Method 1
a pressure accumulator is provided, in particular between the pressure supply device and the safety gate, having a storage chamber for storing a quantity of brake fluid under pressure
Data Source
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AI summary
The invention relates to a brake system having the following: - two brake circuits (BK1, BK2) comprising brake circuit lines (HL4, HL5) for two vehicle axles (VA, HA) and at least one hydraulically operating wheel brake (RB1-4) in each brake circuit (BK1, BK2), wherein each hydraulically operating wheel brake (RB1-4) can be connected to the wheel brake circuit (BK1, BK2) or its brake circuit line (HL4, HL5) via a paired switch valve (SV), and pressure is built up (Pauf) and released (Pab) in at least one wheel brake (RB1-4) via the paired switch valve (SV), and a pressure supply device (DV), wherein pressure is or can be built up (Pauf) in both brake circuits (BK1, BK2) via the pressure supply device (DV), and - at least one circuit separating valve (BP1, BP2) which is open in an unenergized state in particular and which is used to selectively block or release a hydraulic connection line (VL) that connects the two brake circuits (BK1, BK2), at least one outlet valve (ZAV, ZAV1) being provided via which an accumulator container (VB) can be connected to at least one brake circuit (BK1, BK2) in order to release pressure (Pab) directly or via a circuit separating valve (BP1, BP2). A master cylinder (SHZ) which can be actuated by an actuation device, in particular in the form of a brake pedal (1), is provided with only one working chamber (110), and the working chamber can be hydraulically connected to the brake circuit line (HL4, HL5) of a brake circuit (BK1, BK2) via a hydraulic line (HL2, HL3) directly or via a circuit separating valve (BP1, BP2), and a switch valve (FV), in particular a switch valve which is open in an unenergized state, is used to selectively close or release the hydraulic line (HL2, HL3).