Two-Box Brake Layout for Redundant ABS Pressure Control
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Solution Overview
Problem
Existing brake systems for autonomous driving and electric vehicles face challenges in achieving high safety and redundancy requirements, with complex designs, long lengths, and inadequate ABS functions, especially in the event of ESP failure, leading to suboptimal braking distances and pedal feel changes.
Innovation Solution
A two-box brake system design featuring an electric brake booster (X-Boost) connected to a standard ESP unit via hydraulic lines, decoupling the main cylinder piston from the motor drive, and using a parallel pressure supply to maintain consistent pedal travel and redundancy, allowing independent pressure regulation and ABS function, even in ESP failure scenarios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a redundant brake pressure generation system with e-booster and ESP is implemented, then safety and reliability are improved, but device complexity and construction length increase
Solution Approach 1:
The patent combines the e-booster and ESP units into a single integrated brake system. The electric motor-driven pump of the e-booster serves dual purposes: both as a brake booster and as a pressure supply for the ESP unit, eliminating the need for separate redundant pressure generation systems while maintaining safety requirements.
Solution Approach 2:
The e-booster's electric motor-driven pump is designed to perform multiple functions: it acts as both the brake booster pump and the ESP pressure supply pump. This multi-functional design reduces system complexity by eliminating redundant components while ensuring reliable brake pressure generation for both autonomous emergency braking and ABS functions.
2Power
If a coaxial drive with electric motor and gear piston is used, then brake pressure generation is improved, but construction length and weight increase
Solution Approach 1:
The patent transitions from a coaxial (vertical) arrangement to a parallel (horizontal) arrangement of the e-booster and ESP units. This dimensional change allows the units to be positioned side-by-side, reducing the overall construction length in the vertical direction while maintaining the necessary brake pressure generation capability through the electric motor-driven pump.
3Power
If separate pressure supply with electric motor and plunger is implemented, then brake pressure control is improved, but device complexity and length increase
Solution Approach 1:
The patent merges the pressure supply function into the e-booster unit itself. The electric motor-driven pump of the e-booster directly supplies pressure to both the brake booster circuit and the ESP circuit, eliminating the need for a separate pressure supply system with additional motors and plungers, thereby reducing complexity while maintaining effective pressure control.
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 solution provides a compact, cost-effective brake system with consistent pedal feel, improved ABS function, and precise pressure control, enabling axle-by-axle regulation and efficient recuperation control, reducing braking distances and pedal feel changes, while meeting high safety and redundancy standards.
Implementation Method 1
an electric brake booster (X-Boost), connected to a standard ESP unit via hydraulic lines
Data Source
AI summary
A brake system may include an actuating device, in particular a brake pedal; a first piston-cylinder unit having two pistons subjecting the brake circuits to a pressure medium via a valve device, wherein one of the pistons can be actuated by the actuation device; a second piston-cylinder unit having an electric motor drive, a transmission at least one piston to supply at least one of the brake circuits with a pressure medium via a valve device; and a motor pump unit with a valve device to supply the brake circuits with a pressure medium. The brake system may also include a hydraulic travel simulator with a pressure or working chamber which is connected to the first piston-cylinder unit.