Brake-by-Wire Parking Force Distribution Under Actuator Heat Limits
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Solution Overview
Problem
Conventional Brake-by-Wire (B-b-W) technology with independent axle architecture limits the maximum permissible vehicle parking gradient due to temperature-dependent performance of electro-hydraulic or electro-mechanical actuators, leading to potential damage and reduced operational time.
Innovation Solution
A method and system for controlling braking force distribution in a B-b-W braking system that adjusts target braking forces based on the working temperature of actuators, road gradient, friction coefficient, and vehicle weight, using a network of actuator modules and control units to optimize force distribution across axles, thereby extending operational limits and preventing thermal damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If electro-hydraulic or electro-mechanical actuators are used for parking brake function in B-b-W system, then service braking and parking brake functions are integrated, but the maximum permissible vehicle gradient is limited due to temperature-dependent performance
Solution Approach 1:
The control method dynamically adjusts the distribution of braking forces between axles based on real-time operating conditions including temperature, gradient, and friction coefficients. The system transitions from static force distribution to dynamic adaptation, allowing the parking brake to maintain reliability across varying thermal conditions while preserving functional integration.
Solution Approach 2:
The system changes the parameter of braking force distribution based on temperature conditions. When temperature increases, the control unit modifies the braking force allocation to reduce load on heated actuators, thereby maintaining parking capability on gradients while preventing thermal damage to the integrated actuators.
2Reliability
If electro-hydraulic or electro-mechanical actuators hold parking force, then parking function is achieved, but thermal damage occurs after maximum time limit
Solution Approach 1:
The control unit continuously monitors the temperature of the electric motor and adjusts the braking force distribution in real-time based on this feedback. This closed-loop control extends the holding time by dynamically reducing the load on actuators when temperature thresholds are approached, preventing thermal damage while maintaining parking force.
Solution Approach 2:
The system implements periodic temperature monitoring and adjusts braking force distribution in cycles based on temperature conditions. This periodic control allows the actuators to operate within safe thermal limits over extended periods, effectively extending the maximum holding time without causing thermal damage.
3Force
If electric motor delivers continuous torque, then parking force is maintained, but temperature rises causing material damage
Solution Approach 1:
The control method changes the braking force parameter based on temperature conditions. When the electric motor temperature approaches critical levels, the system reduces the braking force delivered by the affected actuator and redistributes the load to other actuators, thereby maintaining sufficient parking force while preventing thermal damage to motor materials.
Solution Approach 2:
The system segments the parking brake function across multiple actuators and axles. When one actuator experiences excessive temperature, the control unit redistributes the parking force to other actuators, effectively segmenting the thermal load and allowing the overheated actuator to cool while maintaining overall parking capability.
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
Enhances the braking system's operability by allowing higher maximum parking gradients and longer holding times without incurring thermal damage to electric motors, leveraging temperature and friction data for improved force management.
Implementation Method 1
the current temperature of the electric motor adapted to convert electrical energy into mechanical energy, thus adapted to actuate the mechanism of the electro-hydraulic or electro-mechanical actuator
Implementation Method 2
the braking action of a brake caliper on a wheel
Data Source
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AI summary
A method (600) for controlling a braking system of a vehicle for the distribution of braking forces for parking the vehicle, comprising steps of: receiving (601), by a control system of a braking system for the distribution of braking forces for parking a vehicle, a first piece of information representative of a first working temperature of a first front axle of the vehicle; receiving (602), by the system, a second piece of information representative of a second working temperature of a second axle of the vehicle; receiving (603), by the system, a third piece of information representative of a gradient of the vehicle; receiving (604), by the system, a fourth piece of information representative of a coefficient of friction between the vehicle and the road; receiving (605), by the system, a fifth piece of information representative of a weight of the vehicle; determining (606), by the system, a first target braking force to be applied to the first front axle of the vehicle to obtain the parking and a second target braking force to be applied to the second rear axle based on the first piece of information representative of a first working temperature of a first front axle of the vehicle, the second piece of information representative of a second working temperature of a second axle of the vehicle, the third piece of information representative of a gradient of the vehicle, the fourth piece of information representative of a coefficient of friction between the vehicle and the road, the fifth piece of information representative of a weight of the vehicle.