Electro-hydraulic Brake System with Independent Circuit Control
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Solution Overview
Problem
Hybrid electric vehicles face challenges in efficiently controlling hydraulic brake force in conjunction with regenerative brake force, as existing systems lack a robust mechanism to manage the difference between driver-demanded braking and regenerative braking, leading to suboptimal energy utilization and braking performance.
Innovation Solution
An electro-hydraulic brake system is developed, featuring a high-pressure accumulator, flow-rate control valves, and mode switching valves to independently control brake oil flow to each wheel circuit, allowing for precise regulation of hydraulic brake force based on driver input and regenerative brake force, with backup paths for emergency braking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single hydraulic circuit is used to control brake force for multiple wheels, then device complexity is reduced, but braking performance and control precision deteriorate due to inability to independently regulate each wheel circuit
Solution Approach 1:
The hydraulic brake system is divided into multiple independent circuits, with each circuit equipped with its own flow-rate control valve. This segmentation allows independent control of brake force for each wheel circuit, improving braking performance while maintaining manageable system complexity through modular architecture.
Solution Approach 2:
The system employs dynamic flow-rate control valves that can adjust their opening degree in real-time based on driving conditions, regenerative brake force availability, and driver input. This dynamic adjustment capability enables precise brake force regulation for each circuit, transforming a static single-circuit system into a dynamically controllable multi-circuit system.
2Device complexity
If hydraulic brake force is controlled without considering regenerative brake force variations, then system simplicity is maintained, but energy utilization efficiency deteriorates
Solution Approach 1:
The control system continuously monitors regenerative brake force output and uses this feedback to dynamically adjust the flow-rate control valves. When regenerative brake force is sufficient, hydraulic brake force is reduced or eliminated; when regenerative force is insufficient, hydraulic supplementation is automatically provided. This feedback mechanism optimizes energy utilization by maximizing regenerative braking while maintaining required braking performance.
Solution Approach 2:
The system dynamically changes the flow rate parameter of brake oil to each circuit based on real-time conditions including regenerative brake force capacity, vehicle speed, and driver braking demand. By adjusting this critical parameter, the system optimizes the balance between regenerative and hydraulic braking, improving overall energy efficiency without compromising safety or performance.
3Device complexity
If flow rate of brake oil is not controlled in each circuit, then device complexity is reduced, but braking performance deteriorates due to inability to independently brake each wheel
Solution Approach 1:
The brake system is segmented into multiple independent hydraulic circuits, each with its own flow-rate control valve. This segmentation enables independent control of brake force application to each wheel or wheel group, improving braking performance and vehicle stability while keeping each control module relatively simple and manageable.
Solution Approach 2:
Flow-rate control valves serve as intermediary devices between the hydraulic power source and the wheel cylinders. These valves mediate the brake oil flow, regulating the amount and timing of hydraulic pressure delivered to each circuit. This intermediary control mechanism enables precise brake force management without requiring complex direct actuation systems at each wheel.
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 system effectively manages hydraulic brake force in conjunction with regenerative braking, enhancing braking performance, reducing costs by using a single circuit for each set of wheels, and ensuring reliable operation through tactile feedback and efficient energy utilization.
Implementation Method 1
a high-pressure accumulator to transmit brake oil independently of the master cylinder
Implementation Method 2
the first circuit includes a first flow-rate control valve to control a flow rate of the brake oil transmitted from the high-pressure accumulator into the first circuit, and the second circuit includes a second flow-rate control valve to control a flow rate of the brake oil introduced into the second circuit
Implementation Method 3
a first pressure sensor provided at an exit side of the first flow-rate control valve to measure pressure of oil introduced into the first circuit, and a second pressure sensor provided at an exit side of the second flow-rate control valve to measure pressure of oil introduced into the second circuit
Data Source
AI summary
Disclosed herein is an electro-hydraulic brake system. The electro-hydraulic brake system includes a master cylinder to transmit brake oil, a high-pressure accumulator to transmit brake oil independently of the master cylinder, first and second circuits connected respectively to the master cylinder, at least one first wheel to be braked by the first circuit, and at least one second wheel to be braked by the second circuit. The first circuit is connected to the high-pressure accumulator, to control the first wheel. The second circuit is connected to the first circuit, to control the second wheel.