Brake Pressure Control Using Actuator Volume Threshold Switching
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Solution Overview
Problem
Brake-by-wire systems in motor vehicles are oversized due to the need to account for various factors affecting brake fluid volume, leading to increased component weight and installation space requirements, especially when a redundant pump is added for synchronous operation with linear actuators.
Innovation Solution
The method involves monitoring the current volume consumption of the linear actuator and switching to synchronous operation with the pump when the consumption exceeds a threshold, allowing the linear actuator to be dimensioned smaller, with the pump providing additional volume as needed for higher pressure requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a redundant pump is added to the brake-by-wire system for synchronous operation with the linear actuator, then the reliability and safety of the braking system is improved, but the device complexity and installation space requirements increase
Solution Approach 1:
The braking system is divided into a primary pressure generation path (linear actuator) and a secondary pressure generation path (pump). This segmentation allows the system to maintain high reliability through redundancy while managing complexity by clearly defining separate functional paths with specific activation conditions.
Solution Approach 2:
The system dynamically switches between single-actuator operation and synchronous dual-actuator operation based on monitored parameters such as volume consumption thresholds. This dynamic adaptation allows the system to maintain reliability only when necessary, reducing overall system complexity during normal operation.
2Reliability
If the linear actuator is dimensioned larger to account for all volume consumption scenarios, then the reliability of achieving blocking pressure is improved, but the weight and installation space requirements increase
Solution Approach 1:
The system changes the operational parameters of the linear actuator by introducing a monitored volume consumption threshold. When this parameter exceeds the threshold, the system activates the pump to supplement pressure generation, allowing the linear actuator to be optimized for normal operation rather than being oversized for worst-case scenarios.
Solution Approach 2:
Instead of designing the linear actuator for excessive capacity to handle all scenarios, the system uses partial action by activating the pump only when volume consumption exceeds the threshold. This allows the linear actuator to be sized for typical operation while the pump provides additional capacity when needed.
3Productivity
If the linear actuator is dimensioned larger to ensure sufficient brake fluid volume delivery, then the productivity of pressure generation is improved, but the device complexity and cost increase
Solution Approach 1:
The system establishes a predetermined volume consumption threshold that triggers pump activation. This preliminary condition allows the linear actuator to be designed for efficient normal operation while ensuring that sufficient brake fluid volume delivery is maintained by activating the pump before volume depletion occurs.
Solution Approach 2:
The control device continuously monitors the volume consumption parameter and provides feedback to determine when to activate the pump. This feedback mechanism ensures that the system maintains sufficient brake fluid volume delivery without requiring the linear actuator to be oversized, as the pump is activated based on real-time volume consumption data.
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 approach reduces the size and weight of the linear actuator, saving space and weight while ensuring sufficient brake pressure is maintained, and allows for a more efficient and optimized braking system design.
Implementation Method 1
a driver's braking request is detected by a specially designed sensor on the brake pedal. Based on this detected braking request, an electro-hydraulic pressure generating device is electronically controlled, which generates the necessary braking pressure in the hydraulic wheel brakes.
Implementation Method 2
the pump is designed to deliver a corresponding volume of brake fluid to the wheel brakes, wherein the sum of the volume delivered by the linear actuator and the volume delivered by the pump corresponds to a required brake fluid volume
Implementation Method 3
A control device is designed to monitor a parameter which describes an actual behavior of the braking system during a braking process and to compare the monitored parameter with a stored threshold value
Implementation Method 4
electro-hydraulic braking systems are characterized by the fact that a driver's braking request is detected by a specially designed sensor on the brake pedal. Based on this detected braking request, an electro-hydraulic pressure generating device is electronically controlled
Data Source
AI summary
The invention relates to a method for controlling a braking system of a motor vehicle, wherein the braking system comprises hydraulically actuated wheel brakes as well as a linear actuator and a pump as electro-hydraulic pressure generating devices, according to which, during a braking process of the motor vehicle, a parameter describing the actual behavior of the braking system of the motor vehicle is monitored and compared with a stored threshold value, wherein, in the event that the monitored parameter has a defined deviation from the threshold value, the linear actuator and the pump are switched to synchronous operation by operating the linear actuator and the pump simultaneously and applying brake pressure to the hydraulically actuated wheel brakes via the linear actuator and the pump.The invention is characterized in that a current volume consumption of the linear actuator is recorded as a parameter describing the actual behavior of the braking system of the motor vehicle.