Vehicle Brake Pressure Control via Gradient Limiting
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Solution Overview
Problem
In vehicle brake devices, when the output pressure reaches a target pressure, the piston may still move, causing overshooting or undershooting due to zero liquid flow rate, leading to deviations from the target pressure.
Innovation Solution
The vehicle brake device includes a pressure adjusting system with electromagnetic valves and a control mechanism to limit pressure gradients, using a limiting necessity judging means to determine when to open or close these valves based on the difference between target and actual output pressures, thereby controlling the flow rate and preventing overshooting or undershooting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If output pressure holding control is executed with zero liquid flow rate when actual output pressure reaches target output pressure, then energy consumption is reduced, but piston movement causes overshooting or undershooting of output pressure
Solution Approach 1:
The control device predicts the piston's future position and the resulting output pressure change before the piston actually moves. By calculating the predicted output pressure based on the piston's current velocity and acceleration, the system takes preliminary action to adjust the liquid flow rate in advance, preventing overshooting or undershooting before they occur.
Solution Approach 2:
The control device dynamically adjusts the liquid flow rate based on the piston's real-time motion state. Instead of using a static zero flow rate control, the system continuously monitors piston velocity and acceleration, and adjusts the flow rate dynamically to counteract the piston's momentum and maintain precise pressure control during the transition to the holding state.
2Loss of time
If liquid flow rate is set to zero for pressure holding control, then response time is improved, but piston inertia causes deviation from target pressure
Solution Approach 1:
The control device performs preliminary calculation of the piston's future position and predicted output pressure before the piston actually moves. By using the piston's current velocity and acceleration to predict future state, the system prepares the appropriate flow rate adjustment in advance, achieving both fast response and accurate pressure control.
Solution Approach 2:
The control device uses feedback from piston position sensors and pressure sensors to continuously monitor the piston's motion state. This feedback information is used to calculate the predicted output pressure and adjust the liquid flow rate in real-time, ensuring that the output pressure remains accurate even during rapid transitions.
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 solution effectively suppresses overshooting and undershooting by adjusting the pressure gradients, ensuring the output pressure remains stable and accurate, improving braking control.
Implementation Method 1
a pressure increasing electromagnetic valve configured to adjust a flow rate of a liquid flowing into the pilot chamber from the high pressure source
Implementation Method 2
a pressure decreasing electromagnetic valve configured to adjust a flow rate of a liquid flowing into the low pressure source from the pilot chamber
Implementation Method 3
a piston driven by a force in difference between a force corresponding to the pilot pressure and a force corresponding to the output pressure
Data Source
AI summary
A vehicle brake device includes a pressure adjusting device wherein as the volume of a pilot chamber is changed by the movement of a piston and the flow rate of liquid flowing in and out of the pilot chamber increases, the amount of movement of the piston increases with reference to the piston position in an equilibrium state where the force corresponding to the pilot pressure and the force corresponding to the output pressure are balanced, whereby the flow rate of the liquid flowing in and out of an output chamber increases. A control device, when judged by a limitation necessity judging portion that the gradient of output pressure should be limited, implements at least one of pressure increasing gradient limit control for opening a pressure decreasing electromagnetic valve under pressure increasing control, or pressure decreasing gradient limit control for opening a pressure increasing electromagnetic valve under pressure decreasing control.