Vehicle Brake System Dynamic Dead Zone Control
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Solution Overview
Problem
Existing vehicle brake systems face challenges in balancing responsiveness and quietness, particularly during emergency braking, where they need to stop the vehicle in a short distance while maintaining stable and quiet operation.
Innovation Solution
A vehicle brake system that incorporates an input piston, an assist piston moved by an electric motor, a master cylinder generating brake fluid pressure, and a control unit that adjusts the electric motor's responsiveness based on the vehicle's state, using a DC brushless motor for enhanced control and quietness, and a ball screw mechanism for precise fluid pressure regulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the electric motor controls the assist piston with high responsiveness to brake pedal operation, then the braking force can be quickly generated, but the system produces unwanted vibrations and noise during low-speed operation
Solution Approach 1:
The control unit dynamically changes the dead zone width based on vehicle speed, making the system characteristics adaptable to different operating conditions. At low speeds, a larger dead zone suppresses vibrations and noise, while at high speeds, a smaller dead zone ensures quick response to brake pedal operations.
Solution Approach 2:
The control parameters (dead zone width) are changed according to vehicle speed. This parameter adjustment allows the system to optimize between responsiveness and vibration suppression depending on the operating condition, resolving the contradiction between these two requirements.
2Object-generated harmful factors
If the dead zone width is increased to suppress vibrations and noise, then quietness is improved, but the responsiveness of brake control deteriorates
Solution Approach 1:
The dead zone width is not fixed but dynamically adjusted based on vehicle speed. This dynamic adjustment allows the system to have large dead zone at low speeds for vibration suppression, and small dead zone at high speeds for responsive control, eliminating the need to choose between these conflicting requirements.
Solution Approach 2:
The control system periodically adjusts the dead zone parameter based on speed conditions, applying different control strategies at different phases of vehicle operation to optimize both quietness and responsiveness in their respective operating ranges.
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 achieves compatibility between responsiveness and quietness by effectively controlling brake fluid pressure, ensuring stable and quiet operation even under emergency braking conditions, while maintaining compactness and reliability.
Implementation Method 1
a brake system has been proposed recently, which performs a boosting operation by using an electric motor instead of negative pressure
Implementation Method 2
an assist piston 21, a ball screw mechanism 32, and a motor 31
Implementation Method 3
a master cylinder 3 that generates a brake fluid pressure based on both of the input piston 11a and assist piston 21
Data Source
AI summary
A brake system which can secure quietness in a passenger compartment is provided. A vehicle brake system 1 includes a brake assist device 2 which boosts a pressing force on a brake pedal 5 by drive of a motor 31, and an assist control unit 6 which controls the motor 31. The assist control unit 6 changes responsiveness of the motor 31 in accordance with a vehicle speed, and sets a dead zone amount and a filtering value to large values in a region with a low vehicle speed. Thereby, responsiveness of a boosting operation of the motor 31 to the operation of the brake pedal is made low, and a rotational variation and a vibration are prevented from occurring to the motor 31 by a minute variation of a detection signal of a stroke sensor 14 during low-speed traveling or stoppage of traveling.