Powertrain Controller Brake Fade Mitigation via Engine Braking
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing vehicle braking systems face challenges in managing brake fade, particularly during adaptive cruise control and downhill driving, as they do not effectively account for the thermal capacity of the braking system, leading to reduced stopping power and potential overheating.
Innovation Solution
A controller-based system that predicts brake fade by monitoring temperature, vehicle speed, mass, and inclination, and adjusts the vehicle's speed setpoint and transmission gear to downshift and increase negative torque, thereby reducing brake fade and maintaining braking performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If friction brakes are continuously applied to maintain vehicle speed during downhill driving, then vehicle speed control is maintained, but brake fade occurs and stopping power is reduced
Solution Approach 1:
The system performs preliminary action by predicting brake fade before it occurs. The controller monitors brake temperature and driving conditions (downhill grade, vehicle speed) to anticipate brake capacity degradation, then proactively reduces the speed setpoint and applies engine braking to prevent the brakes from overheating, rather than waiting for brake fade to occur
Solution Approach 2:
The system introduces engine braking as an intermediary mechanism between the vehicle's speed control需求和 the friction brake system. By downshifting the transmission and utilizing engine compression braking, the system provides an alternative means to slow the vehicle, reducing the thermal load on the friction brakes while maintaining speed control
2Reliability
If brake temperature is monitored to prevent brake fade, then brake performance is maintained, but system complexity increases
Solution Approach 1:
The system implements feedback by continuously monitoring brake temperature and using this information to adjust the speed setpoint. The controller receives temperature data from sensors, compares it against thresholds, and automatically modifies cruise control parameters to prevent brake overheating, creating a closed-loop control system that adapts to thermal conditions
Solution Approach 2:
The system performs self-service by automatically adjusting its own operating parameters (speed setpoint, transmission gear) based on brake thermal conditions. The cruise control system monitors its own brake usage patterns and autonomously modifies its behavior to prevent brake fade, without requiring external intervention or complex additional control 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
The system effectively mitigates brake fade by proactively downshifting the transmission and reducing engine speed, thereby alleviating the demand on friction brakes and preventing thermal saturation, ensuring consistent braking performance even under heavy use.
Implementation Method 1
friction between a rotor and a brake lining, where the brake lining is on a brake pad, or friction between a drum and a brake lining
Implementation Method 2
heat can be vented away from the rotor and pads
Implementation Method 3
heat can be vented away from the rotor and pads
Data Source
AI summary
A cruise control system for a vehicle includes a controller configured to maintain a speed of the vehicle about a setpoint, and in response to predicted brake capacity falling below a threshold based on predicted brake fade, reduce the setpoint and downshift a transmission of the vehicle to increase negative torque to reduce brake fade. Also, a powertrain of a vehicle includes an engine, an automatic transmission coupled with the engine, and a controller. The controller is configured to maintain a speed of the vehicle about a setpoint, and in response to a predicted brake capacity falling below a threshold based on predicted brake fade, reduce the setpoint and downshift the transmission to increase a negative torque.