Active Brake Torque Variation Cancellation via Decoupled Actuation
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Solution Overview
Problem
Brake torque variation in vehicle brake systems due to circumferential variation in disc brake rotor thickness or drum cylindricity leads to vibrations and brake roughness, which existing technologies fail to effectively mitigate without affecting the brake pedal feel.
Innovation Solution
A de-coupled electro-mechanical brake actuation system that adjusts the output time and volume of pressurized brake fluid based on the frequency and phase of detected brake torque variation to cancel out vibrations, using a controller that receives signals from sensors to modulate hydraulic fluid pressure and flow accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a coupled brake actuation system is used to suppress rotor resonant vibration, then brake torque variation is reduced, but the brake pedal feel becomes extremely hard or soft
Solution Approach 1:
The brake actuation system is divided into two independent parts: a coupled actuation system for normal braking operation and a separate active cancellation system for suppressing brake torque variation. The active cancellation system includes independent actuators that apply counteracting forces without affecting the brake pedal mechanism, thus resolving the contradiction between BTV reduction and pedal feel maintenance
Solution Approach 2:
An active cancellation system acts as an intermediary between the brake pads and rotor. This system uses sensors to detect BTV and applies compensating forces through independent actuators, effectively canceling out the harmful vibrations without interfering with the driver's brake pedal input or the hydraulic brake system
2Power
If hydraulic pressure is increased to improve braking force, then deceleration performance is improved, but brake torque variation and vibrations are exacerbated
Solution Approach 1:
The active cancellation system applies periodic counteracting forces at the same frequency as the detected brake torque variation but in the opposite phase. This periodic action effectively cancels out the harmful vibrations caused by disc thickness variation, allowing high hydraulic pressure to be used for improved braking force without exacerbating BTV
Solution Approach 2:
The system uses sensors to continuously monitor brake torque variation and feeds this information back to the active cancellation actuators. The actuators then adjust their output in real-time to counteract the detected vibrations, enabling the system to maintain high braking force while actively suppressing BTV through closed-loop control
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
Effectively reduces brake torque variation by compensating for disc thickness variations without altering the brake pedal feel, thereby minimizing vibrations and improving braking stability.
Implementation Method 1
A de-coupled electro-mechanical brake actuation system that adjusts the output time and volume of pressurized brake fluid based on the frequency and phase of detected brake torque variation to cancel out vibrations
Data Source
AI summary
Systems and methods for cancelling brake torque variation in a motor vehicle are disclosed. Signals indicative of brake torque variation are received at a controller. Based on the signals, a frequency associated with the indicated brake torque variation is determined. At least one of an output time and output volume of pressurized brake fluid is adjusted based on the frequency to cancel the indicated brake torque variation.