Hydraulic Brake Circuit Switching for Pressure Generator Failure
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Solution Overview
Problem
Conventional hydraulic braking systems in motor vehicles face challenges in identifying and responding to errors without redundant hydraulic systems, particularly in highly automated vehicles, where safety is critical and driver feedback is limited in electrically assisted braking systems.
Innovation Solution
A braking system with dedicated electric actuators and an emergency operation valve that disconnects and connects brake circuits, allowing for safe operation by redistributing hydraulic pressure between circuits in case of failure, and includes a shared tank and independently operable pressure generators to ensure continuous braking functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If redundant hydraulic systems are implemented to ensure safety, then reliability is improved, but device complexity and cost increase
Solution Approach 1:
The patent merges the two brake circuits through the emergency operation valve, allowing them to be disconnected during normal operation but connected during emergency operation. This enables a single pressure generator to serve both circuits when needed, eliminating the need for completely redundant hydraulic systems while maintaining safety.
Solution Approach 2:
The emergency operation valve dynamically switches between two states: disconnected during normal operation to allow independent pressure generation in each circuit, and connected during emergency operation to enable cross-circuit pressure distribution. This dynamic configuration allows the system to adapt its redundancy level based on operational needs.
2Ease of operation
If the brake pedal is hydraulically decoupled from the brake circuit for wireless braking, then ease of operation is improved, but the driver's ability to identify errors deteriorates
Solution Approach 1:
The emergency operation valve provides a feedback mechanism to the driver. When activated, it creates a detectable change in pedal sensation, informing the driver of system errors or emergency conditions. This maintains error detectability despite hydraulic decoupling by providing tactile feedback about system state.
Solution Approach 2:
The emergency operation valve acts as an intermediary between the electric braking system and the driver. It translates internal system errors into external tactile feedback through the pedal, allowing the driver to perceive system errors without direct hydraulic connection.
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
Enables safe and cost-effective operation of the braking system by ensuring continuous hydraulic pressure generation across all brake circuits even if one pressure generator fails, without the need for redundant hydraulic systems, maintaining vehicle safety and stability.
Implementation Method 1
the emergency operation valve is switched in such a way that the brake circuits are disconnected from one another... the brake circuits are connected to one another by the activation of the emergency operation valve so that, for example in the event of a failure of one pressure generator, the remaining pressure generator may be utilized for generating a hydraulic pressure in the two brake circuits
Implementation Method 2
at least two brake circuits which each include at least one hydraulically actuatable wheel brake and at least one electrically operable pressure generator, the pressure generators being activatable as a function of a brake request
Data Source
AI summary
A hydraulic braking system for a motor vehicle, including at least two brake circuits which each include at least one hydraulically actuatable wheel brake and at least one electrically operable pressure generator, the pressure generators being activatable as a function of a brake request of the motor vehicle or a driver of the motor vehicle. A respective electric actuator is assigned to each pressure generator for its operation, and at least one activatable emergency operation valve is interconnected between the brake circuits, which in a first switching position disconnects the brake circuits from one another and in a second switching position connects them to one another.