ESC Regenerative Braking Control for Linear Hydraulic Pressure
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Solution Overview
Problem
Conventional ESC integrated regenerative braking systems face challenges in generating linear hydraulic pressure during rear-wheel regenerative braking, resulting in non-uniform braking forces due to high spring force in the split valve, which limits the ability to match the driver's desired braking force.
Innovation Solution
An apparatus and method that include a pedal cylinder unit, a motor driven by an electric signal, a master cylinder unit, and oil pressure relief valves, controlled by a unit to manage oil pressure across wheel cylinders, allowing for front-wheel pressure control, reverse pressure control, and drive pressure control to achieve linear hydraulic pressure generation during rear-wheel regenerative braking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high spring force is applied in the split valve to prepare for circuit failure, then system reliability is improved, but hydraulic pressure generation linearity deteriorates
Solution Approach 1:
The patent segments the brake system into front-wheel hydraulic braking and rear-wheel regenerative braking zones. The split valve is configured to isolate front-wheel hydraulic pressure generation from rear-wheel operations, allowing independent optimization of each zone. This segmentation enables the spring force in the split valve to be optimized for reliability without compromising rear-wheel pressure linearity.
Solution Approach 2:
The patent extracts the function of rear-wheel hydraulic pressure generation from the main brake circuit by implementing a dedicated rear-wheel pressure control path. This extraction allows the rear-wheel regenerative braking system to operate independently, generating hydraulic pressure through a separate mechanism that does not suffer from the spring force non-linearity affecting the main circuit.
2Use of energy by moving object
If regenerative braking force is applied at rear wheels, then energy recovery is improved, but braking force uniformity deteriorates
Solution Approach 1:
The patent implements dynamic control of the motor operating as a generator during regenerative braking. The control unit adjusts the motor's electromagnetic braking torque in real-time based on feedback from pressure sensors and current sensors, ensuring uniform braking force distribution. This dynamic adjustment compensates for the non-linear characteristics of the split valve spring force.
Solution Approach 2:
The patent employs a feedback control mechanism where pressure sensors monitor hydraulic pressure in both front and rear wheel circuits, and current sensors monitor motor current. The control unit processes this feedback information and adjusts the motor's regenerative braking torque accordingly, maintaining uniform braking force despite the non-linear spring force characteristics.
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 enables linear oil pressure control on rear wheels, improving regenerative braking coordinated control performance without the need for additional valves, reducing noise from valve control, and ensuring the desired braking force is applied uniformly.
Implementation Method 1
a motor that is operated in response to displacement of the brake pedal
Implementation Method 2
generate a braking oil pressure through a master piston that is moved forward or backward
Data Source
AI summary
Provided are an apparatus and method for performing rear-wheel regenerative braking control of an ESC integrated regenerative braking system. The apparatus includes: a pedal cylinder unit connected with a reserve unit in which oil is stored and configured to generate an oil pressure as a brake pedal is pressed; a motor driven by an electric signal that is output in response to displacement of the brake pedal; a master cylinder unit connected with the pedal cylinder unit; a control unit configured to perform reverse pressure control on the motor as much as a variation in a rear-wheel regenerative braking force if transition of the rear-wheel regenerative braking force occurs, and perform drive pressure control on the motor if the transition of the rear-wheel regenerative braking force is completed; and oil pressure relief valves provided on oil pressure lines that connect from the reserve unit to wheel cylinders.