Redundant EV Brake Circuits With Dual Pressure Supply Control
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Solution Overview
Problem
Current braking systems for electric vehicles, particularly in fully automated driving (FAD) and autonomous driving (AD) levels, face challenges in meeting high availability and redundancy requirements, with limitations in dynamic control, noise reduction, and integration with electric drive motors, while also being cost-effective and reliable.
Innovation Solution
A brake system design that incorporates redundant electronic control units, hydraulically assisted electromechanical brakes, and a central control unit for coordinated pressure supply and control, allowing for wheel-specific control and redundancy in event of component failures, with a focus on closed brake circuits and multiplex operation to reduce dynamic demands on electric motors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If redundant pressure supply units are implemented for high availability in autonomous driving, then system reliability is improved, but device complexity and cost increase
Solution Approach 1:
The braking system is divided into two independent brake circuits (first and second brake circuits), each with its own pressure supply unit. This segmentation allows one circuit to operate independently if the other fails, providing redundancy without requiring complete duplication of the entire braking system. The patent implements this by creating separate hydraulic circuits that can function autonomously.
Solution Approach 2:
The first pressure supply unit is designed to perform multiple functions: it can supply pressure to both the first brake circuit and the second brake circuit. This multi-functionality reduces the need for completely separate redundant systems. The patent achieves this through a universal pressure supply unit that can selectively pressurize different brake circuits based on operational requirements.
2Reliability
If closed brake circuits are used to improve safety and reduce leakage, then reliability is improved, but pressure control complexity increases
Solution Approach 1:
The patent introduces intermediary components such as check valves and control valves that mediate between the pressure supply units and the closed brake circuits. These intermediaries allow pressure to be introduced and controlled in a systematic way without requiring the entire closed circuit system to be overly complex. The check valves prevent backflow while control valves regulate pressure entry into the closed circuits.
3Reliability
If electric brake boosters are replaced with redundant pressure supply units, then reliability for autonomous driving is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces the traditional electric brake booster (EBK) mechanical system with a redundant pressure supply system that uses hydraulic principles. Instead of relying on a single electric motor-driven booster, the system uses multiple pressure supply units that can independently generate braking pressure through hydraulic actuators, eliminating the need for complex electric motor control systems while improving reliability.
4Reliability
If triple redundancy is implemented for Level 4 and 5 autonomous driving, then system availability is improved, but cost and device complexity increase significantly
Solution Approach 1:
The patent implements partial redundancy by providing alternative pressure supply paths rather than complete triple redundancy of all components. The first pressure supply unit can serve both brake circuits, and the second pressure supply unit provides backup for the second circuit. This partial redundancy approach achieves sufficient availability for autonomous driving without the excessive complexity and cost of full triple redundancy across all system 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 ensures high availability and performance by maintaining maximum deceleration and driving stability even with component failures, with reduced noise and costs, and supports advanced driving dynamics functions like torque vectoring and steering.
Implementation Method 1
each having an electric motor drive which adjusts a piston position in the pressure supply device
Implementation Method 2
piston-cylinder unit (HZ), wherein the piston (3) adjusts a pressure in a pressure chamber (4)
Data Source
Figure 1
Figure 1a
Figure 1b
AI summary
The invention relates to a braking system for a vehicle, comprising: - at least two hydraulic brake circuits (BK1, BK2) each with at least one hydraulically actuated wheel brake (RB1, RB2, RB3, RB4), - at least two pressure supply devices (DV1, DV2) driven by an electric motor drive (MI, M2), - at least one electronic control unit, one of which is a higher-level central control unit (M-ECU) that controls individual control units of components of the braking system, and - at least one additional electric drive motor (TM1, TM2) for at least one axle or wheel of the vehicle, wherein the additional electric drive motor (TM1, TM2) is used to drive and brake the axle or wheel.of the wheel is usable, wherein - the braking system for steering interventions (torque vectoring) uses the at least one pressure supply device (DV1, DV2) for pressure control in at least one wheel brake (RB) and/or the at least one electric drive motor (TM1, TM2), wherein different braking torques are generated at the axles for brake force distribution and/or at the wheels of an axle for generating a yaw moment or steering intervention (torque vectoring) by means of the at least one wheel brake (RB1, RB2, RB3, RB4) and/or the at least one drive motor (TM1, TM2).