Brake Hydraulic Pressure Control Device Turning Point Offset
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Solution Overview
Problem
Conventional brake hydraulic pressure control devices using normally open linear solenoid valves experience significant changes in turning point current values due to varying time intervals of pressure reduction, leading to inconsistent brake feel and performance.
Innovation Solution
A brake hydraulic pressure control device that adjusts the power supply to normally open and closed solenoid valves to control hydraulic pressure, determining a turning point target hydraulic pressure by subtracting an offset pressure from the previous pressure reduction start, ensuring stable and favorable brake feel by maintaining consistent braking patterns across cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the turning point current value is calculated based on the current value at the end of previous increasing cycle and a predetermined ratio, then the brake hydraulic pressure control device can adapt to pressure reduction, but the turning point current value changes greatly when pressure reduction amount varies, causing inconsistent brake feel
Solution Approach 1:
The patent changes the calculation method of the turning point current value from using a predetermined ratio of current variation to using a predetermined pressure value offset from the pressure reduction start point. This parameter change in the calculation approach ensures that the turning point current value remains stable and does not vary greatly with different pressure reduction amounts, thereby maintaining consistent brake feel while still adapting to pressure reduction conditions.
2Duration of action of moving object
If the power supply amount is lowered at a steep gradient to the turning point current value, then high caliper pressure is maintained for longer time, but the turning point current value instability causes brake feel deterioration
Solution Approach 1:
The patent changes the definition of the turning point current value from being ratio-based to being offset-based (subtracting a predetermined pressure value from the pressure reduction start point). This ensures that the turning point current value remains stable across different pressure reduction scenarios, allowing the system to maintain high caliper pressure for longer durations without compromising brake feel consistency.
3Adaptability or versatility
If the turning point current value varies significantly with different pressure reduction amounts, then the brake control adapts to different conditions, but the braking pattern changes greatly and brake feel becomes unfavorable
Solution Approach 1:
The patent implements a parameter change in the turning point current value calculation by using a fixed pressure offset method instead of a variable ratio method. This ensures that while the brake control remains adaptable to different pressure reduction conditions, the turning point current value itself remains stable, thereby maintaining consistent and favorable brake feel across all operating 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
The solution ensures a stable and favorable brake feel by maintaining consistent turning point target hydraulic pressures, allowing for prolonged high braking force application and improved control according to road surface conditions.
Implementation Method 1
a normally open linear solenoid valve (1) arranged in a hydraulic pressure passage from the master cylinder to the wheel brake, the normally open linear solenoid valve being configured to adjust a valve closing force depending on an power supply amount
Implementation Method 2
a normally closed solenoid valve (2) arranged in a hydraulic pressure passage from the wheel brake to the master cylinder
Data Source
AI summary
A brake hydraulic pressure control device includes: a normally open linear solenoid valve configured to adjust a valve closing force depending on an power supply amount; a normally closed solenoid valve; and a controller configured to control switching of a hydraulic pressure within the wheel brake between a pressure increasing state, a pressure holding state, or a pressure reducing state, wherein: when shifting to the pressure increasing state from the pressure reducing state or the pressure holding state is made, the controller controls the power supply amount so that increasing is made at a first gradient up to a turning point target hydraulic pressure, and increasing is made at a second gradient gentler than the first gradient from the turning point target hydraulic pressure up to the end of the increasing; and the controller determines the turning point target hydraulic pressure.