Hydraulically Open Brake Circuits for Redundant Autonomous Braking
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current brake systems for highly automated or autonomous vehicles are unsuitable as they require mechanical and hydraulic interventions by a driver, which is not present in autonomous driving scenarios, leading to inefficiencies and increased complexity.
Innovation Solution
A multiple-circuit hydraulically open brake system with a modular design featuring two assemblies - a main system and a secondary system, each with independent energy supplies and control units, allowing for electric actuation without driver intervention, and incorporating a modulation unit for individual brake pressure modulation, ensuring redundancy and efficient brake performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If brake systems are designed for driver intervention with tandem brake master cylinders and power-assisted systems, then sufficient brake force can be maintained for fallback scenarios, but the system complexity and component count increase significantly
Solution Approach 1:
The brake system is divided into two independent brake circuits (first and second brake circuits), each with its own pressure generator, control unit, and energy supply. This segmentation allows each circuit to independently provide full braking capability, eliminating the need for complex tandem master cylinders while maintaining reliability through redundancy.
Solution Approach 2:
The patent replaces traditional mechanical driver intervention systems (tandem master cylinders, hydraulic boosters, pedal travel simulators) with electrically actuated pressure generators. Each pressure generator uses an electric motor to directly generate brake pressure, eliminating the need for mechanical linkages and hydraulic boosting mechanisms while achieving the same or better braking performance.
2Reliability
If traditional brake systems with driver intervention mechanisms are used, then fallback braking capability is ensured, but installation space requirements increase due to multiple connectors and components
Solution Approach 1:
The system divides braking functions into two independent circuits that can be spatially separated and distributed throughout the vehicle. Each circuit has its own pressure generator and control unit, allowing flexible installation arrangements that reduce space requirements compared to centralized traditional brake systems with multiple connectors at each wheel.
Solution Approach 2:
Each pressure generator and control unit is designed to perform multiple functions: normal braking, fault detection, and fallback braking. This multi-functionality eliminates the need for separate dedicated fallback components, reducing overall installation space while maintaining the capability to provide sufficient braking force in failure scenarios.
3Reliability
If multiple valves and mechanisms for driver pressure generation are included, then brake system redundancy is achieved, but manufacturing costs and system weight increase
Solution Approach 1:
The patent replaces heavy mechanical components (tandem master cylinders, hydraulic boosters, pedal mechanisms) with lighter electrically actuated pressure generators. Each pressure generator uses an electric motor and direct pressure generation mechanism, significantly reducing component weight while maintaining or improving braking performance and redundancy.
Solution Approach 2:
The system changes the fundamental operating parameters from mechanical force multiplication (through lever arms and hydraulic ratios) to direct electric actuation with controlled pressure generation. This parameter change allows for more compact, lighter components that achieve the same braking force through electrical power rather than mechanical leverage.
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 results in a simpler, more cost-effective, and lightweight brake system with reduced noise, vibration, and harshness, capable of maintaining sufficient brake performance even in fault conditions, while allowing for integration in both right-hand and left-hand drive vehicles with reduced installation space requirements.
Implementation Method 1
two pressure generators (12, 22) which are connected hydraulically in parallel between at least one fluid vessel (17, 27) and the at least two wheel brakes (RB1, RB2, RB3, RB4)
Implementation Method 2
a modulation unit (16, 16A, 16B, 16C, 16D) for the hydraulic connection of the pressure generators (12, 22) to the at least two wheel brakes (RB1, RB2, RB3, RB4) and for an individual brake pressure modulation in the at least two wheel brakes (RB1, RB2, RB3, RB4)
Implementation Method 3
a first shut-off valve (V1, V2) to at least one wheel brake (RB1, RB2, RB3, RB4) of a first brake circuit (BK1, BK2) and via a second shut-off valve (V2, V3) to at least one wheel brake (RB1, RB2, RB3, RB4) of a second brake circuit (BK1, BK2)
Data Source
AI summary
A multi-circuit, hydraulically open brake system includes a first pressure generator assigned to a main system with a first energy supply and a first evaluation and control unit (ECU), and is connectable via a first shut-off valve to wheel brake(s) of a first brake circuit and via a second shut-off valve to wheel brake(s) of a second brake circuit. A second pressure generator is assigned to a secondary system which includes a second energy supply and a second ECU, and is connectable via a third shut-off valve to wheel brake(s) of the first brake circuit and via a fourth shut-off valve to wheel brake(s) of the second brake circuit. The second ECU controls the second pressure generator. Components of the modulation unit for individual brake pressure modulation are assigned to the main system, and the components are controlled by the first ECU and are supplied by the first energy supply.