Hydraulically Open Braking System for Autonomous Vehicles
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Solution Overview
Problem
Existing brake systems for highly automated or autonomous vehicles lack a robust and cost-effective architecture that can maintain adequate braking performance without driver intervention, especially in fault conditions, due to the absence of a driver to assist in hydraulic braking.
Innovation Solution
A multi-circuit hydraulically open brake system with two independent brake circuits, each connected to a pressure generator, where a first pressure generator is designed as a plunger system for the main system and a second as a pump system for the secondary system, allowing for redundant braking performance without mechanical or hydraulic driver intervention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional brake system with driver hydraulic intervention is used, then the driver can assist during braking, but the system becomes unsuitable for highly automated or autonomous vehicles where no driver is present to assist
Solution Approach 1:
The patent replaces the mechanical hydraulic intervention system (master cylinder, booster) with an electromechanical system consisting of an electric motor-driven pump and electronic control unit. This substitution eliminates the need for driver physical intervention while maintaining braking functionality in autonomous vehicles.
2Device complexity
If a single brake circuit is used to reduce complexity, then the system becomes simpler, but the braking performance and safety in fault conditions deteriorate
Solution Approach 1:
The patent divides the brake system into two independent brake circuits (first brake circuit and second brake circuit), each with its own pressure generator and control unit. This segmentation allows the system to maintain braking functionality even if one circuit fails, thereby improving reliability while managing complexity through modular design.
3Reliability
If multiple independent pressure generators and control units are implemented for redundancy, then braking reliability in fault conditions improves, but system complexity and cost increase
Solution Approach 1:
The patent combines the two independent pressure generators into a single integrated pressure generator with two piston systems (first piston system and second piston system) that share common components such as the housing, fluid supply connection, and hydraulic unit. This merging approach maintains the redundancy and reliability benefits of independent circuits while reducing overall system complexity and cost through shared infrastructure.
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
This design provides a simple, robust, and cost-effective braking system with reduced components, lower weight, and improved Noise, Vibration, Harshness (NVH) performance, enabling adequate braking even in fault conditions and allowing for integration of advanced control functions like ABS and ESP.
Implementation Method 1
the first pressure generator increases or reduces pressure in the brake circuits by means of a first piston system, and maintains the pressure by means of a first shut-off valve
Implementation Method 2
the second pressure generator increases or reduces pressure in the brake circuits by means of a second piston system or pump system
Data Source
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AI summary
The invention relates to a multiple-circuit hydraulically open braking system (1), in particular for a highly automated or autonomous vehicle, and a corresponding operating method for a braking system (1) of this type, comprising at least two wheel brakes (RB1, RB2, RB3, RB4) each assigned to a braking circuit (BK1, BK2) having a pressure relief path (9.1, 9.2), two multiple-circuit pressure generators (12, 22) hydraulically connected in series between a fluid container (7) and the at least two wheel brakes (RB1, RB2, RB3, RB4), and a hydraulic unit (16) for hydraulically connecting the pressure generator (12, 22) to the at least two wheel brakes (RB1, RB2, RB3, RB4) and for individual brake pressure modulation in the at least two wheel brakes (RB1, RB2, RB3, RB4), wherein a first pressure generator (12) is designed as a plunger system and assigned to a main system (10) having a first energy supply (EV1) and a first evaluation and control unit (14), wherein a second pressure generator (22) is designed as a second plunger system or as a pump system and is assigned to a secondary system (20) having a second energy supply (EV2) that is independent from the first energy supply (EV1) and a second evaluation and control unit (24), which actuates the second pressure generator (22), wherein components of the hydraulic unit (16) are assigned to the main system (10) for individual brake pressure modulation, such that said components of the hydraulic unit (16) and the first pressure generator (12) are actuated by the first evaluation and control unit (14) and supplied with energy by the first energy supply (EV1).