Vehicle Braking System with Segmented Hydraulic Circuits
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Solution Overview
Problem
Existing braking systems in electric and hybrid vehicles face challenges in providing a consistent braking torque that matches driver input, especially when transitioning between recuperative and hydraulic braking, and often require complex and costly brake-by-wire systems to adapt to varying driving conditions.
Innovation Solution
A braking system with a variable and switchable idle travel mechanism, utilizing a first valve to control the brake actuation element's idle travel and a second valve to manage pressure in the master brake cylinder, allowing for adjustable braking torque distribution between recuperative and hydraulic braking modes, and including a control device to switch between modes based on valve states, ensuring efficient energy recuperation and safe braking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a brake-by-wire system is used to adapt braking torque to driver input, then the consistency of braking feel is improved, but the device complexity and cost increase significantly
Solution Approach 1:
The braking system is segmented into two independent brake circuits: a first brake circuit connected to a brake medium reservoir for recuperative braking, and second brake circuits connected to the master brake cylinder for direct hydraulic braking. This segmentation allows each circuit to operate independently, eliminating the need for complex brake-by-wire systems while maintaining consistent braking feel through the direct hydraulic connection in the second circuits.
Solution Approach 2:
The system uses the driver's direct actuation of the brake pedal to self-regulate the hydraulic braking torque. When the driver presses the brake pedal, brake medium is directly pressurized in the master brake cylinder and transmitted to the second brake circuits, providing immediate and consistent braking feedback without requiring complex electronic sensors, controllers, or actuators.
2Loss of energy
If the generator is activated as a recuperative brake to ensure high energy savings, then the energy recuperation efficiency is improved, but the total braking torque may not match the driver's brake pedal actuation
Solution Approach 1:
The braking system is divided into two independent brake circuits: a first brake circuit for recuperative braking connected to the generator and a brake medium reservoir, and second brake circuits for direct hydraulic braking connected to the master brake cylinder. This segmentation allows the recuperative brake to operate independently to maximize energy recovery while the direct hydraulic brake circuits maintain consistent braking torque matching driver input.
Solution Approach 2:
The system merges two braking mechanisms (recuperative braking and direct hydraulic braking) into a unified braking system where both can operate simultaneously or independently. The first brake circuit handles energy recovery through the generator, while the second brake circuits provide direct hydraulic braking torque, and their effects are combined at the wheels to achieve both high energy savings and consistent braking feel.
3Device complexity
If a fixed pedal free travel is implemented, then the hydraulic brake system structure is simplified, but the ability to adapt to different braking modes (recuperative vs. direct braking) is reduced
Solution Approach 1:
The system segments the braking function into two independent circuits: the first brake circuit with variable free travel for recuperative braking, and the second brake circuits with fixed or minimal free travel for direct hydraulic braking. This segmentation allows each circuit to be optimized for its specific function while maintaining overall system simplicity.
Solution Approach 2:
The first brake circuit implements dynamic free travel adjustment through a control device that can vary the free travel distance between the brake actuation element and the brake medium reservoir based on operating conditions. This dynamic adjustment allows the system to adapt between recuperative and direct braking modes without requiring complex brake-by-wire systems, maintaining structural simplicity while enhancing versatility.
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 enables efficient energy recuperation, reduces the need for complex electronics, and provides a cost-effective alternative to brake-by-wire systems by allowing adjustable braking torque distribution and safe braking even in case of electronic failures, while maintaining a consistent braking feel across different driving conditions.
Implementation Method 1
a first valve, via which a brake circuit with at least one wheel brake cylinder is hydraulically connected to the master brake cylinder
Implementation Method 2
a second valve, via which the master brake cylinder is hydraulically connected to at least one wheel brake cylinder
Implementation Method 3
into which a predetermined storage volume of a brake medium can be transferred without counter-pressure
Data Source
AI summary
The invention relates to a braking system for a vehicle, having a main brake cylinder (10) having a main brake cylinder floating piston that can be at least partially shifted into the main brake cylinder (10), and having a brake medium storage device (12, 20) into which a predetermined storage volume of a brake medium can be transferred without backpressure, wherein the brake medium storage device (12, 20) is hydraulically connected to the main brake cylinder (10) by means of an electrically controllable first valve (18) in such a way that when the main brake cylinder floating piston is shifted partially into the main brake cylinder (10) by a shift travel that is less than a shift travel limit corresponding to the storage volume, a volume of brake medium that is less than the predetermined storage volume can be transferred from the main brake cylinder (10) without backpressure into the brake medium storage device (12, 20) via the at least partially opened first valve (18). The invention further relates to a method for operating a braking system for a vehicle.