Brake System Special Control Mode for Back Pressure Management
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Solution Overview
Problem
The existing 'brake-by-wire' systems face damage risks due to high back pressure caused by inertia of the electromechanical actuator during panic braking, leading to potential system bursting, as closing all inlet valves results in post-displacement of pressure medium from the pressure chamber.
Innovation Solution
A special control mode is implemented where at least one selected wheel brake's inlet valve remains open and the associated outlet valve is temporarily opened to allow pressure medium to flow into a storage container, preventing damage by managing pressure medium displacement through the outlet valve.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If all inlet valves are closed during anti-lock control to terminate brake pressure build-up, then brake pressure control is achieved, but high back pressure occurs due to post-displacement of pressure medium from the pressure chamber, causing damage to the electromechanical actuator or bursting of the system
Solution Approach 1:
The patent extracts the harmful post-displacement volume of pressure medium from the closed system by opening the outlet valve of a selected wheel brake, allowing the excess pressure medium to be discharged from the pressure chamber through the outlet valve to the wheel brake and back to the reservoir, thereby eliminating the high back pressure that would otherwise damage the electromechanical actuator
Solution Approach 2:
The outlet valve of a selected wheel brake serves as an intermediary pathway for the pressure medium. Instead of directly confronting the harmful back pressure in the closed system, the outlet valve provides a controlled release path that mediates between the pressure chamber and the reservoir, allowing safe discharge of the post-displacement volume
2Productivity
If the electromechanical actuator is operated highly dynamically during panic braking to achieve high-pressure build-up gradients, then safety is improved, but the inertia of the actuator causes post-displacement of pressure medium, leading to high back pressure
Solution Approach 1:
The control unit determines in advance, before the harmful back pressure builds up, that the outlet valve of a selected wheel brake should be opened. This preliminary action prepares the discharge path for the pressure medium, ensuring that when the electromechanical actuator's inertia causes post-displacement, the pressure medium has a ready pathway to escape, preventing the development of dangerous back pressure
Solution Approach 2:
The patent converts the harmful effect of the electromechanical actuator's inertia, which causes unwanted post-displacement of pressure medium, into a beneficial controlled discharge process. By opening the outlet valve, the system allows the inertia-driven movement to safely expel pressure medium through the selected wheel brake's outlet valve to the reservoir, transforming a potential damage source into a controlled pressure management mechanism
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 solution effectively prevents damage to the brake system by ensuring pressure medium is discharged safely, maintaining system integrity and preventing bursting, while allowing for efficient pressure build-up and release during critical operating states.
Implementation Method 1
an electrically controlled pressure supply device which is formed by a cylinder-piston assembly with a hydraulic pressure chamber
Implementation Method 2
owing to the inertia of the electromechanical actuator
Data Source
AI summary
A method for operating a brake system for motor vehicles comprises in a normal control mode of the system, a displacement of a piston for a pressure supply device is terminated, and inlet valves of the wheel brakes are closed in the event of a specified brake condition. The normal control mode is switched to a special control mode in the event of a specified condition for the pressure supply device. In the event of the specified brake condition in the special control mode, a displacement of the piston of the pressure supply device is terminated by outputting an actuation signal to the pressure supply device, and for at least one selected wheel brake, the corresponding inlet valve is kept open and the corresponding outlet valve is opened at least temporarily while the inlet valves of the remaining wheel brakes are closed.