Automotive Brake Pressure Control Without Fallback Hydraulics
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Solution Overview
Problem
Existing brake systems for highly automated driving are complex and costly, requiring multiple electrically activatable valves and a mechanical or hydraulic fallback plane, which complicates manufacturing and reliability, especially in the absence of a driver's muscle force for actuation.
Innovation Solution
A brake system with a double-wound electric motor and solenoid-actuated 2/2-way inlet valves that can manage pressure differences from both directions, eliminating the need for sequence valves and check valves, and featuring redundant electronic control units for actuation redundancy, allowing continued operation even after individual electrical or electronic faults.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple electrically activatable valves and a mechanical or hydraulic fallback plane are used to ensure reliability for highly automated driving, then the availability and reliability of the brake system is improved, but the device complexity and manufacturing cost increase
Solution Approach 1:
The patent removes the mechanical or hydraulic fallback plane from the brake system, eliminating the associated complexity of multiple valves and redundant actuation mechanisms. The system relies solely on the electrically actuatable pressure source with electronic redundancy, thereby reducing device complexity while maintaining reliability through electronic backup systems.
Solution Approach 2:
The electrically actuatable pressure source is designed to perform both primary braking function and fallback function through electronic control redundancy. The single pressure source can be actuated by either the first or second electronic control unit, making it a universal component that replaces multiple specialized components (sequence valves, check valves, dual pressure sources), thus reducing overall system complexity.
2Reliability
If sequence valves and check valves are added to manage pressure differences and enable pressure medium flow, then the reliability of pressure control is improved, but the device complexity and manufacturing cost increase
Solution Approach 1:
The patent eliminates sequence valves and check valves from the brake system by designing the electrically actuatable pressure source with controlled pressure output. The pressure source directly manages pressure differences through electronic control, removing the need for additional passive valve components and simplifying the manufacturing process.
Solution Approach 2:
The patent replaces mechanical pressure management components (sequence valves, check valves) with an electrically controlled pressure source that uses electronic actuation to manage pressure differences. This substitution reduces the number of mechanical parts, simplifying manufacturing and assembly while maintaining reliable pressure control.
3Reliability
If a mechanical or hydraulic fallback plane is implemented for driver actuation, then the reliability for non-electrical operation is improved, but the device complexity and cost increase
Solution Approach 1:
The patent removes the mechanical or hydraulic fallback plane entirely, recognizing that electronic redundancy in the control units provides sufficient reliability for highly automated driving. This elimination reduces system complexity and removes components that would require mechanical linkages and hydraulic fallback circuits.
Solution Approach 2:
The patent changes the approach to fallback reliability from mechanical/hydraulic redundancy to electronic control redundancy. The electrically actuatable pressure source with dual electronic control units provides fallback capability through software and control logic rather than physical backup systems, reducing overall system complexity while maintaining reliability for automated operation.
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 reduces complexity and cost by eliminating unnecessary valves and fallback mechanisms, ensuring high availability and reliability for highly automated driving by maintaining brake pressure and enabling deceleration even with reduced dynamics.
Implementation Method 1
can be closed in relation to pressure differences from both directions by actuating its solenoid coil
Implementation Method 2
the piston is able to be pushed forward and backward by an electric motor
Implementation Method 3
electrically actuatable hydraulic pressure source for at least four hydraulically activatable wheel brakes
Data Source
AI summary
A brake system for a motor vehicle includes hydraulic output ports for activatable wheel brakes. The system includes an electrically actuatable hydraulic pressure source The system also includes a pressure medium reservoir under atmospheric pressure. An electrically activatable inlet valve is connected between each output port and the pressure source. An electrically activatable outlet valve is connected between each outlet port and the pressure medium reservoir Each of the inlet valves is embodied as a 2/2-way valve and in such a manner that the inlet valve can be closed in relation to pressure differences from both directions and can be opened in relation to pressure differences from both directions.