Redundant EV Brake Circuits With Pressure Supply Backup Control
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Solution Overview
Problem
Existing braking systems for electric vehicles and vehicles with automated driving levels 3 to 5 face challenges in achieving high availability, redundancy, and precise control, particularly due to issues with hydraulic components like seals, solenoid valves, and ball screw drives, which can lead to failures and undesired vehicle deceleration.
Innovation Solution
A braking system with a pressure supply device featuring redundant electronic control and regulating units, hydraulically supported electromechanical brakes, and electric drive motors, operating in a closed brake circuit with multiplex methods, and utilizing traction motors for additional redundancy and precise pressure control without pressure sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydraulic brake systems with seals, solenoid valves, and ball screw drives are used, then braking function is achieved, but system reliability deteriorates due to component failures and undesired vehicle deceleration
Solution Approach 1:
The braking system is divided into two independent brake circuits (first and second brake circuits), each capable of providing full braking function independently. This segmentation ensures that a failure in one circuit does not compromise the overall braking system, directly improving reliability while eliminating the harmful effect of single-point failures
Solution Approach 2:
The system implements beforehand cushioning by providing redundant pressure supply capabilities through multiple independent brake circuits and pressure sources. This preparatory redundancy ensures that if one circuit fails, the system can immediately compensate without experiencing undesired vehicle deceleration or loss of braking function
2Reliability
If redundant pressure supply is implemented for high availability, then system reliability improves, but device complexity increases
Solution Approach 1:
The patent merges the redundancy requirement into a unified dual-circuit brake system where both brake circuits share common control and coordination mechanisms. This merging approach achieves the necessary redundancy for high availability while reducing overall complexity compared to completely separate independent systems
Solution Approach 2:
The brake system is designed with universal components that can serve multiple functions across both brake circuits. The pressure supply device and control units are configured to provide multi-functional operation, allowing the same hardware to support redundant operations without proportionally increasing device complexity
3Manufacturing precision
If closed brake circuits are used with multiplex methods, then precise pressure control is achieved, but control system complexity increases
Solution Approach 1:
The control system implements dynamic pressure control through the multiplex method, where control parameters and circuit configurations can change in real-time based on operating conditions. This dynamic approach enables precise pressure control while the system adapts to different scenarios, managing complexity through flexibility rather than rigid additional 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
Ensures high availability and precise control, allowing for rapid braking and stability even in the event of component failures, with reduced dynamic demands on electric motors and enhanced safety through redundant systems and diagnostic methods.
Implementation Method 1
An electric motor (M1) serves to build up pressure in a pressure chamber (DR) by displacing a piston (KB)
Implementation Method 2
The pressure chamber (DR) can be connected to a brake circuit (BK) via a hydraulic line (HL)
Implementation Method 3
The hydraulic line (HL) can be connected to a separating valve (TV), by means of which the pressure supply device (DV1) can be separated from the brake circuit (BK)
Data Source
AI summary
A brake system for a vehicle may contain redundant components that permit braking force to be applied in case of partial or complete failure of a primary braking mechanism. The system may include at least one hydraulic brake circuit having at least one hydraulically operating wheel brake; a pressure supply device driven by an electric-motor drive; at least one electronic control and regulating device; a valve assembly having valves for setting wheel-specific brake pressures and/or for (dis)connecting the wheel brakes (from)to the pressure supply device; a piston-cylinder unit actuable by an actuating device, which can be connected to the at least one hydraulic brake circuit, to at least one brake unit comprising an electric drive motor, to an electric parking brake, to a hydraulically supported electromechanical brake, and/or to an electromechanical brake; at least one electric drive motor for at least one axle or wheel; and a central control unit.