Hydraulic Brake Pressure Control with Reduced Activation Threshold
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Solution Overview
Problem
Hydraulic brakes in vehicles experience reduced effectiveness at high temperatures due to decreased friction between brake pads and discs, leading to prolonged stopping distances and ineffective FBS function activation, as the existing FBS method fails to consistently support brake pressure during high thermal loads and saline exposure.
Innovation Solution
The method involves switching on the energy supply unit when the brake pressure exceeds a first activation threshold and switching it off at a bottom threshold, with a counter checking for a new pressure rise using a reduced activation threshold or pressure gradient, allowing for quicker reactivation of the FBS function.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the energy supply unit is switched on when brake pressure exceeds the first activation threshold, then the brake pressure is increased to compensate for fading, but the FBS function deactivates too early when pressure drops below the threshold, causing long phases with reduced braking effectiveness
Solution Approach 1:
The patent introduces a second, reduced activation threshold (pAT,red) that is lower than the first activation threshold (pAT). This parameter change allows the FBS function to reactivate at lower brake pressures, preventing long deactivation phases and maintaining continuous braking support during high thermal load conditions.
2Reliability
If the activation threshold is set high to ensure adequate brake pressure, then the FBS function activates reliably, but it fails to reactivate after pressure drops, especially at very high temperatures where pressure cannot rise sufficiently
Solution Approach 1:
The patent adapts the activation threshold parameter based on operating conditions by introducing a reduced threshold (pAT,red) for reactivation scenarios. This allows the system to respond appropriately to varying temperature conditions, ensuring FBS function reactivation even when brake pressure cannot reach the original high threshold due to thermal effects.
Solution Approach 2:
The patent makes the activation threshold dynamic by using different threshold values depending on the operational context: the first threshold (pAT) for initial activation and the second reduced threshold (pAT,red) for reactivation. This dynamic approach allows the system to adapt to changing thermal conditions and maintain effectiveness throughout the braking process.
3Reliability
If the pump runs continuously to maintain brake pressure, then braking effectiveness is consistently improved, but energy consumption increases significantly
Solution Approach 1:
The patent uses periodic activation of the FBS function based on brake pressure threshold comparisons. The energy supply unit is activated only when needed (when pressure drops below thresholds) rather than running continuously, achieving periodic action that balances braking effectiveness with energy efficiency.
Solution Approach 2:
The patent implements feedback control by continuously monitoring brake pressure and comparing it against activation thresholds. The FBS function is activated or deactivated based on this feedback, ensuring energy is used only when braking support is actually needed rather than consuming energy continuously.
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 shortens phases with deactivated FBS function, enhancing braking effectiveness and reducing stopping distances by reactivating the FBS function more promptly, even at low pressure rises, thus improving the overall braking performance.
Implementation Method 1
hydraulic fluid is pumped out of the master brake cylinder into the wheel brakes
Implementation Method 2
hydraulic fluid flows back into the master brake cylinder
Implementation Method 3
a pressure sensor adapted to sense the brake pressure in the master brake cylinder
Data Source
AI summary
Disclosed is a method for increasing the braking effect in a motor vehicle having a hydraulic brake system. An energy supply unit, which is used to increase the brake pressure in at least one wheel brake, is switched on when the brake pressure adjusted by the driver in a master brake cylinder exceeds a first activation threshold value, which is determined depending on a detected vehicle deceleration, and the energy supply unit is switched off when the brake pressure reaches a predetermined bottom threshold value at a specific instant. According to the method, within an interval beginning at that specific instant, it is checked whether the brake pressure (pTMC) rises again using a comparison between the brake pressure and a second activation threshold (pAT,red) that is reduced compared to the first activation threshold (pAT) and/or using a comparison between a brake pressure gradient and a predetermined threshold value, and in that the energy supply unit is switched on again when a new rise of the brake pressure (pTMC) has been detected. Also disclosed is a device that is suitable for implementing the method.