Electro-Hydraulic Brake Timing Control for Rear Wheel Inversion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The rear wheel inversion phenomenon occurs when emergency braking is required, causing the braking pressures of rear wheels to increase earlier than those of front wheels, which degrades the braking stability of a vehicle during electronic brake-force distribution (EBD) implementation.
Innovation Solution
A method is introduced to control the electro-hydraulic brake system by closing the inlet valve connected to the rear wheel brake for a predetermined time until a motor reaches a certain speed, then opening it, to prevent premature pressure increase in rear wheels and maintain stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the EBD function is implemented to adjust braking forces of rear wheels, then braking performance is improved, but rear wheel inversion occurs causing braking stability to degrade
Solution Approach 1:
The inlet valve connected to the rear wheel brake is closed in advance for a predetermined time period before the motor reaches a certain rotational speed. This preliminary action prevents brake fluid from being supplied to the rear wheel brake too early, thereby preventing the rear wheel inversion phenomenon and maintaining braking stability while still allowing the EBD function to improve braking performance.
2Speed
If the inlet valve is opened immediately to supply brake fluid to rear wheel brake, then braking force is generated earlier, but rear wheel inversion occurs degrading stability
Solution Approach 1:
The inlet valve is closed in advance for a predetermined time period to control the timing of brake fluid supply. This preliminary timing control ensures that brake fluid is supplied to the rear wheel brake at the appropriate moment, preventing rear wheel inversion while still enabling timely generation of braking force.
Solution Approach 2:
The inlet valve switching timing is dynamically adjusted based on the motor's rotational speed. The valve is closed for a predetermined time until the motor reaches a certain speed, then opened. This dynamic timing control optimizes both the speed of braking force generation and the stability of braking by adapting to the real-time operating conditions of the motor.
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 effectively prevents rear wheel inversion, thereby enhancing the braking stability of the vehicle during EBD by ensuring that the braking pressures of rear and front wheels are synchronized, improving overall vehicle stability during emergency braking.
Implementation Method 1
a motor connected to a main master cylinder to increase hydraulic pressure
Implementation Method 2
closing an inlet valve connected to a rear wheel brake for a predetermined time so that a pressure of the rear wheel brake is not increased earlier
Data Source
AI summary
According to at least one aspect, the present disclosure provides a method of controlling an electro-hydraulic brake including an electronic brake-force distribution (EBD) control function, the method comprising: an emergency braking determination operation of determining whether emergency braking is required for a vehicle; a motor control operation of controlling a current flowing in a motor connected to a main master cylinder to increase hydraulic pressure supplied to wheel brakes when it is determined that the emergency braking is required; a rear wheel inlet valve closing operation of closing an inlet valve connected to a rear wheel brake for a predetermined time so that a pressure of the rear wheel brake is not increased earlier than a pressure of a front wheel brake; a closed time period calculation operation of calculating a time during which the inlet valve is maintained in a closed state; and a rear wheel inlet valve opening operation of determining whether a time during which the inlet valve is closed exceeds a closed time period (t), maintaining the inlet valve in the closed state until the time reaches the closed time period (t), and opening the inlet valve when the time exceeds the closed time period (t).