Double-Stroke Brake Pressure Supply for Fault-Tolerant Hydraulics
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Solution Overview
Problem
Current hydraulic brake systems face challenges in ensuring reliable braking performance, especially in autonomous driving scenarios, where double faults leading to total brake failure must be avoided, and stringent safety requirements need to be met across various levels of automation.
Innovation Solution
A brake system with a pressure supply device featuring a double-action piston, which includes a hydraulic connection with switchable valves and check valves, allowing for effective pressure management and fault detection, thereby preventing double faults and ensuring braking performance even in fault conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a hydraulic brake system is designed to meet stringent safety requirements for autonomous driving, then braking reliability is improved, but system complexity increases due to multiple pressure supply devices and circuits
Solution Approach 1:
The brake system is divided into multiple independent hydraulic brake circuits (first brake circuit BK1, second brake circuit BK2), each with its own pressure supply capability. This segmentation allows the system to maintain braking reliability even if one circuit fails, while avoiding the need for a single complex redundant system
Solution Approach 2:
The double-action piston DHK serves multiple functions: it can generate brake pressure in both forward and return strokes, connect to different brake circuits selectively, and provide evacuation capability. This multi-functionality reduces the need for separate dedicated components for each function, thereby reducing overall system complexity
2Reliability
If double faults are prevented through redundant pressure supply, then safety is improved, but the number of components and valves increases
Solution Approach 1:
The first and second pressure supply devices are merged into a single double-action piston DHK that can supply pressure to both brake circuits. This combining approach provides redundant pressure supply capability while reducing the total number of separate components compared to having two independent pressure supply devices
Solution Approach 2:
The check valves RV3-RV6 automatically manage pressure distribution and circuit isolation without requiring active control. The system uses passive hydraulic elements that self-regulate based on pressure differentials, reducing the need for additional active control components
3Productivity
If a double-action piston is used for pressure supply in both directions, then productivity is improved, but device complexity increases compared to single-action pistons
Solution Approach 1:
The double-action piston DHK enables continuous pressure supply to the brake circuits by utilizing both the forward stroke and return stroke for pressure generation. This eliminates idle time between pressure deliveries, improving the overall productivity and responsiveness of the brake system
Solution Approach 2:
The piston mechanism is designed to dynamically switch between different operational modes (supplying first brake circuit BK1, supplying second brake circuit BK2, or evacuating) based on system requirements. This dynamic adaptability allows a single piston to replace what would traditionally require multiple static components
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 effectively prevents double faults, ensures reliable braking across different automation levels, and maintains braking performance even in fault conditions, meeting stringent safety requirements by enabling timely identification and management of dormant individual faults.
Implementation Method 1
a pressure supply device (DV), which is connected via a hydraulic line to a brake circuit (BK1, BK2)
Implementation Method 2
the double-action piston, in the forward stroke and/or return stroke, is connected via a check valve (RV5, RV6), which opens toward the pressure supply device (DV), to the reservoir (VB)
Data Source
AI summary
A brake system for a vehicle has at least one pressure supply device which is connected to a brake circuit via a hydraulic line. Furthermore, the brake system has a hydraulic connection between at least one of the brake circuits and an accumulator container, said connection being switchable via at least one outlet switch valve, and the pressure supply device has a double stroke piston with a working stroke and a return stroke. The double stroke piston can be at least partly emptied via the outlet switch valve.