Electric Parking Brake Control for Voltage Dip Prevention
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Solution Overview
Problem
Electrically supported brake systems face challenges in ensuring sufficient braking force when the electrical support fails, leading to increased pedal travel and force requirements, which can result in insufficient braking forces, especially when using low-volume tandem main cylinders and potentially causing rear-wheel axle lockup and high current uptake during maximum braking efforts.
Innovation Solution
The method involves pre-energizing the parking brake actuators upon detection of impending brake pedal actuation, using pulse-width modulation to limit and control the braking force, and monitoring wheel slip to avoid lockup, thereby reducing current supply load and maintaining a standby state to enhance response speed and prevent current peaks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the electric parking brake is used as an additional service brake to provide maximum braking force, then the braking force is improved, but the current uptake increases and may cause voltage dips
Solution Approach 1:
The parking brake actuators are pre-energized upon detection of impending brake pedal actuation, placing them in a standby state before full braking is required. This preliminary action allows the actuators to be ready for rapid response while managing current consumption by not applying full braking force immediately
Solution Approach 2:
The control system dynamically adjusts the energization state of the parking brake actuators based on detected braking conditions. The actuators transition between different operational states (standby, partial braking, full braking) to optimize the balance between providing necessary braking force and managing current uptake from the electrical system
2Speed
If the parking brake actuators are rapidly energized to build up maximum braking force, then the response speed is improved, but current peaks occur
Solution Approach 1:
The actuators are pre-energized to a standby state before full braking is needed, allowing magnetic fields to begin building without immediately applying full mechanical braking force. This reduces inrush current peaks while maintaining readiness for rapid response when braking is actually required
Solution Approach 2:
The control system uses periodic or pulsed energization patterns during the braking process, particularly during the initial phase, to build up braking force while managing current consumption. This allows the system to achieve rapid response without sustained high current peaks
3Device complexity
If the electrically supported brake system uses low-volume tandem main cylinders, then the device complexity is reduced, but the braking force becomes insufficient when electrical support fails
Solution Approach 1:
The parking brake actuators are designed to serve multiple functions: traditional parking brake operation and additional service brake support. When the electrically supported brake system experiences failures or insufficient braking force, the parking brake actuators can be activated to provide supplementary braking force, making the system more versatile and reliable without adding complex backup systems
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 ensures rapid and controlled braking force buildup, reduces the risk of rear-wheel lockup, and minimizes current peaks, allowing the parking brake to function effectively as an additional service brake, even when the regular service brake or electric support is limited, while maintaining efficient energy use and preventing voltage dips.
Implementation Method 1
providing an actuator (12, 14) having an electric motor (200)
Implementation Method 2
The conversion of the motor rotation into a linear motion is usually carried out through a reduction gear and a self-locking worm gear, and so the braking force can be maintained in a currentless state
Implementation Method 3
the actuators selectively press a brake shoe onto the brake disk or release the brake disk
Data Source
AI summary
A method for controlling an electric parking brake for a motor vehicle including a brake actuator having an electric motor disposed directly on the brake caliper. When the parking brake is utilized as an additional service brake, depending on a brake pedal brake command, the electric motor is initially energized on detection of an imminent or commencing brake-pedal actuation however the electric motor generates no braking force until a predetermined or specific brake command is received. As a result, an overload of the vehicle voltage source is avoided if simultaneous utilization of multiple parking-brake actuators occurs.