Vehicle Brake Control for Stable Front-Rear Force Ratio
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Solution Overview
Problem
Existing braking control systems for vehicles with regenerative braking devices struggle to maintain a constant ratio between front and rear wheel braking forces, which is crucial for directional stability during regenerative braking, especially when one of the regenerative braking devices falls into disorder.
Innovation Solution
A braking control device that includes an actuator and a controller, where the actuator supplies brake fluid pressure to both front and rear wheel cylinders, ensuring the rear wheel brake fluid pressure is equal to or greater than the front wheel pressure, and the controller calculates and adjusts the required braking forces to maintain a constant ratio between the rear and front wheel braking forces, utilizing both regenerative and friction braking forces as needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the rear wheel brake fluid pressure is set equal to or greater than the front wheel brake fluid pressure in a single pressurizing system, then the system complexity is reduced and ease of manufacture is improved, but the ability to maintain a constant ratio between front and rear wheel braking forces deteriorates
Solution Approach 1:
The patent applies dynamics by making the braking force distribution adaptive rather than fixed. The controller dynamically adjusts the braking force ratio based on real-time conditions, allowing the system to maintain optimal front-rear braking force distribution despite the physical constraint of a single pressurizing system. This is achieved through continuous monitoring and adjustment of brake fluid pressure distribution to front and rear wheel cylinders.
Solution Approach 2:
The patent changes the parameter of brake fluid pressure distribution dynamically. By adjusting the pressure parameters supplied to front and rear wheel cylinders independently through the single pressurizing system, the controller can maintain the desired braking force ratio. This involves changing pressure levels based on vehicle speed, deceleration demand, and regenerative braking availability.
2Loss of energy
If regenerative braking force is maximized for energy recovery, then energy efficiency is improved, but the reliability of braking force distribution deteriorates when regenerative braking devices fall into disorder
Solution Approach 1:
The patent applies beforehand cushioning by preparing backup friction braking capability alongside regenerative braking systems. When regenerative braking devices fall into disorder, the friction braking system immediately compensates to maintain reliable braking force distribution. This dual-system approach ensures energy efficiency during normal operation while providing reliability assurance when regenerative braking fails.
Solution Approach 2:
The controller acts as an intermediary that coordinates between regenerative braking devices and friction braking systems. It monitors the status of regenerative braking and dynamically switches or blends between regenerative and friction braking forces to maintain reliable braking performance. This intermediary control ensures smooth transition and maintains braking force ratio even when regenerative braking is compromised.
3Stability of the object's composition
If independent control of front and rear wheel braking forces is implemented, then braking force distribution is optimized, but the device complexity increases
Solution Approach 1:
The patent applies universality by using a single pressurizing system to perform multiple functions: generating brake fluid pressure for both front and rear wheel cylinders, and providing both regenerative and friction braking capabilities. This multi-functional approach achieves independent control of front and rear wheel braking forces without requiring separate pressurizing systems, thus optimizing braking force distribution while limiting device complexity increase.
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 configuration optimizes the relationship between front and rear wheel braking forces, ensuring vehicle stability by maintaining a constant ratio even when one regenerative braking device is compromised, allowing for efficient energy regeneration and improved directional stability.
Implementation Method 1
front and rear wheel regenerative braking devices (KCf, KCr) that generate front and rear wheel regenerative braking forces (Fgf, Fgr)
Implementation Method 2
an actuator (HU) that supplies a front wheel brake fluid pressure (Pwf) to a front wheel cylinder (CWf) and a rear wheel brake fluid pressure (Pwr)
Implementation Method 3
generates front and rear wheel frictional braking forces (Fmf, Fmr) on the front and rear wheels (WHf, WHr)
Data Source
AI summary
An actuator supplies a front wheel brake fluid pressure and a rear wheel brake fluid pressure equal to generate front and rear wheel frictional braking forces. A controller calculates a braking force required as a whole of a vehicle, and calculates front and rear wheel required braking forces so that a sum of the front and rear wheel required braking force matches a target vehicle body braking force and the ratio of the rear wheel required braking force to the front wheel required braking force is a constant value. A rear wheel restricted regenerative braking force is calculated by multiplying the maximum front wheel regenerative braking force by a constant value, and the smaller one of maximum rear wheel regenerative braking force and the rear wheel restricted regenerative braking force is determined as the rear wheel reference regenerative braking force.