Regenerative Braking Fluid Pilot Control for Backup Transition
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Solution Overview
Problem
Conventional regenerative braking systems face challenges in maintaining reliable braking torque when transitioning to a backup level, leading to reduced braking comfort and safety due to sudden losses in generator braking torque.
Innovation Solution
The method involves pilot control of brake fluid volumes to compensate for increased intake in wheel brake cylinders, ensuring sufficient brake pressure can be maintained by transferring fluid to the wheel brake cylinders, even when generator braking torque is lost, using a hydraulic actuator to close air gaps and establish a setpoint volume considering estimated increased volume intake, friction values, or warning information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the regenerative braking system transitions to backup level due to loss of generator braking torque, then the vehicle can still be braked using friction brakes, but the braking comfort and safety are reduced due to sudden loss of generator braking torque
Solution Approach 1:
The control unit performs preliminary actions by detecting warning information about imminent transition to backup level and activating the hydraulic actuator to transfer brake fluid to the wheel brake cylinders in advance. This preliminary fluid transfer ensures that sufficient brake pressure is available immediately when generator braking torque is lost, preventing the sudden braking comfort degradation that would otherwise occur during transition to backup level.
2Ease of operation
If brake fluid is transferred to wheel brake cylinders to close air gaps and maintain brake pressure, then braking comfort is improved, but brake fluid volume in the system is redistributed which requires precise control
Solution Approach 1:
The control unit employs feedback mechanisms by continuously monitoring the braking state, generator braking torque availability, and brake fluid pressure. Based on this feedback, the control unit determines when warning information about imminent backup level transition is present and calculates the appropriate amount of brake fluid to transfer to wheel brake cylinders, ensuring precise fluid volume control that maintains braking comfort while managing system complexity.
3Reliability
If the hydraulic actuator is activated to transfer brake fluid in advance, then sufficient brake pressure is available during backup level transition, but energy is consumed during the fluid transfer process
Solution Approach 1:
The system applies preliminary anti-action by detecting warning information about imminent transition to backup level and pre-transferring brake fluid to wheel brake cylinders before the actual transition occurs. This preliminary action ensures that when generator braking torque is suddenly lost, sufficient brake pressure is already available in the wheel brake cylinders, preventing the harmful effect of brake pressure deficiency during backup level transition. The hydraulic actuator is activated only when warning information is present, not during normal 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
This approach enhances braking comfort and safety by allowing drivers to maintain effective braking without significant pedal travel, even after the regenerative braking system transitions to its backup level, thereby increasing acceptance and safety standards.
Implementation Method 1
activating the at least one hydraulic actuator of the regenerative braking system in such a way that at least sufficient brake fluid is transferable via the at least one hydraulic actuator to the at least one wheel brake cylinder
Data Source
AI summary
A method for operating a regenerative braking system of a vehicle by activating at least one motor employable in generator mode taking into consideration a first information with regard to a requested setpoint total braking torque and a second information with regard to an available generator braking torque which is maximally executable by the at least one motor employable in generator mode, if the setpoint total braking torque exceeds a threshold value and/or a piece of warning information regarding a transition to a backup level that is potentially imminent or has occurred of the regenerative braking system, even if the setpoint total braking torque is less than or equal to the maximally executable available generator braking torque, sufficient brake fluid is transferred via at least one hydraulic actuator to a wheel brake cylinder of the regenerative braking system that an air gap of the particular wheel brake cylinder is closed.