Brake Solenoid Valve Current Control via Sine Wave
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing brake systems face challenges in maintaining optimal braking performance due to differences between estimated and actual pressures in the wheel cylinder, leading to rapid degradation of braking performance, especially when the difference between the master cylinder and wheel cylinder pressures increases.
Innovation Solution
The proposed solution involves controlling the solenoid valve current using a combination of sine wave and on/off patterns to adjust the pressure in the wheel cylinder, creating an upward sloping pressure waveform, which helps in maintaining stable pressure control and reducing noise and pulsation, thereby improving braking performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a sensor is not mounted in the wheel cylinder to reduce cost, then cost competitiveness is improved, but the pressure control precision deteriorates because actual pressure cannot be directly measured
Solution Approach 1:
The patent creates a virtual copy of the pressure measurement function by using motor current as a proxy indicator. Instead of directly measuring pressure with a sensor, the system copies the pressure information through electrical measurement of the motor driving the hydraulic pump, thereby avoiding the need for expensive pressure sensors while maintaining control capability.
Solution Approach 2:
The patent introduces motor current as an intermediary parameter between the hydraulic pressure system and the control system. By measuring motor current instead of direct pressure, the system uses an intermediate electrical parameter to infer mechanical pressure state, solving the measurement problem without direct pressure sensing.
2Stress or pressure
If the difference between master cylinder and wheel cylinder pressure increases, then the brake system can handle larger pressure variations, but braking performance degrades rapidly due to estimation errors
Solution Approach 1:
The patent implements a feedback control mechanism where motor current measurements continuously inform the control system about the actual pressure state. By feeding back this electrical parameter and adjusting the motor driving signal accordingly, the system maintains accurate pressure control even when large pressure differences exist between master and wheel cylinders, preventing performance degradation.
Solution Approach 2:
The patent employs dynamic control by continuously adjusting the motor driving signal based on real-time motor current feedback. This dynamic adjustment allows the system to adapt to changing pressure conditions and maintain optimal braking performance across varying pressure differential conditions.
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 allows for stable wheel pressure control, reducing noise and pulsation, and maintaining robust braking performance even when there are errors in pressure estimation, and can be applied to various systems like ABS and ESC, enhancing the overall braking system's efficiency.
Implementation Method 1
An anti-lock braking system (ABS) and an electronic stability control (ESC) system generate a magnetic field by passing a current to a solenoid coil, and operate by opening or closing the corresponding solenoid valve using the magnetic field.
Data Source
AI summary
A method for controlling a solenoid valve current of a brake system may include: determining, by a controller, whether a difference between the pressure of a master cylinder and the pressure of a wheel cylinder is equal to or more than a preset reference value; and forming, by the controller, the pressure of the wheel cylinder by applying a sine wave pattern to an on/off control pattern while applying a current to a solenoid valve for adjusting the pressure of the wheel cylinder such that the pressure of the wheel cylinder is changed in an LMV control manner based on an upward sloping pattern, when the determination result indicates that the difference between the pressure of the master cylinder and the pressure of the wheel cylinder is equal to or more than a preset reference value.