Vehicle Behavior Control Device Diagonal Wheel Pressure Adjustment
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Solution Overview
Problem
Conventional vehicle behavior control devices fail to stabilize vehicle behavior during automatic brake control in electric vehicles, as they incorrectly determine brake operation status, leading to reduced hydraulic pressures in diagonal wheels and inadequate suppression of oversteering and understeering.
Innovation Solution
A vehicle behavior control device that adjusts hydraulic pressures in diagonal wheels to the master cylinder pressure during both manual and automatic brake operations, using an electrical hydraulic pressure generator and ECU to ensure appropriate braking pressure application, even when the brake pedal is not operated, thereby maintaining vehicle stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If brake operation determination is based on upstream pressure sensor values in electric vehicles with electric hydraulic brakes, then the brake operation status can be detected, but the determination becomes inaccurate during automatic brake control (regenerative brake cooperative control) when the brake pedal is not operated but brake force is still applied
Solution Approach 1:
The patent introduces a brake operation determination unit that acts as an intermediary between the pressure sensor and the vehicle behavior control. This unit combines multiple information sources (upstream pressure sensor values, driver-requested hydraulic pressure from stroke sensor, and automatic brake control status) to accurately determine brake operation status, resolving the contradiction between detection accuracy and control reliability during automatic brake control
Solution Approach 2:
The brake operation determination mechanism is designed to handle multiple brake control modes (manual brake operation, regenerative brake cooperative control, and other automatic brake controls) through a single unified determination system. The system adapts its determination criteria based on the current brake control mode, ensuring reliable vehicle behavior control across all operating conditions
2Use of energy by moving object
If regenerative brake cooperative control is implemented to increase regenerative energy quantity, then energy efficiency improves, but the brake operation status becomes difficult to determine accurately when the brake pedal is not operated
Solution Approach 1:
The patent employs feedback mechanisms where the brake operation determination unit continuously monitors upstream pressure sensor values and driver-requested hydraulic pressure, and compares them with the automatic brake control status. This feedback loop enables accurate determination of brake operation status during regenerative brake cooperative control, allowing the system to maintain both high regenerative energy utilization and accurate brake status detection
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 enhances the vehicle's ability to suppress oversteering and understeering disturbances by ensuring consistent hydraulic pressure application to diagonal wheels during automatic brake control, improving overall vehicle behavior stabilization performance.
Implementation Method 1
an electrical hydraulic pressure generator that is connected to the master cylinder and electrically generates a hydraulic pressure based on the operation with the brake pedal
Implementation Method 2
a wheel cylinder that is arranged in each wheel of the vehicle for braking
Data Source
AI summary
A vehicle behavior control device is for use in a vehicle including a brake pedal, a master cylinder generating a hydraulic pressure in response to an operation with the brake pedal, an electric hydraulic pressure generator connected to the master cylinder and electrically generating a hydraulic pressure based on the operation with the brake pedal, and a wheel cylinder in each wheel for braking. The device controls a brake hydraulic pressure to be applied to the wheel cylinder to control vehicle behavior. When brake control is executed such that a brake hydraulic pressure not based on the operation with the brake pedal is generated if the brake pedal is not being operated, a hydraulic pressure applied to a wheel cylinder in a diagonal wheel positioned diagonal from a brake wheel for controlling the behavior of the vehicle is adjusted to the hydraulic pressure in the master cylinder.