Brake Booster Layout for Redundant Pressure Control
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Solution Overview
Problem
Existing braking systems for autonomous and electric vehicles are cumbersome, heavy, and complex, with long dimensions and high weight, failing to provide optimal redundancy and safety, especially in cases of system failures, and do not allow for precise control of braking pressure across all wheels.
Innovation Solution
A compact 2-box braking system with a simplified electric brake booster design, decoupled from the engine drive, featuring a short and narrow master cylinder with a parallel pressure supply, allowing independent control of each axle and precise pedal characteristics, and redundant power supplies, enabling efficient pressure modulation and reduced weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a redundant brake booster function with ESP unit and pump is implemented, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent combines the brake booster function and ESP unit into a single integrated system. The master cylinder piston is directly coupled to the wheel cylinders, eliminating the need for separate booster and ESP components while maintaining redundant braking capability through the direct mechanical connection
Solution Approach 2:
The master cylinder piston serves multiple functions: it provides both the brake booster function for normal braking and the ESP function for stability control. This multi-functional design eliminates the need for separate dedicated components for each function, reducing overall system complexity
2Stress or pressure
If a coaxial drive with gearbox and piston is used, then brake pressure generation is improved, but length increases
Solution Approach 1:
The patent removes the gearbox and intermediate transmission components from the system. The electric motor is directly coupled to the master cylinder piston, eliminating the need for a gearbox while maintaining effective brake pressure generation through direct mechanical action
Solution Approach 2:
Instead of using a complex coaxial drive with gearbox, the patent inverts the approach by using a direct linear actuation mechanism where the electric motor moves the master cylinder piston directly, achieving the same pressure generation function with reduced length
3Reliability
If pedal travel is made independent of fading and brake circuit failure, then reliability is improved, but device complexity increases
Solution Approach 1:
The master cylinder piston automatically compensates for brake fading and circuit failures through its direct mechanical coupling to the wheel cylinders. The system self-regulates pedal travel characteristics without requiring external sensors, actuators, or complex control mechanisms
Solution Approach 2:
The master cylinder piston acts as a mechanical intermediary that directly transmits pedal force to the wheel cylinders, ensuring consistent pedal travel characteristics regardless of system conditions. This direct mechanical mediation eliminates the need for complex electronic control systems
4Device complexity
If common pressure control for all four wheels is implemented, then device complexity is reduced, but braking distance increases
Solution Approach 1:
The patent segments the brake system into independent wheel cylinder controls while maintaining a simple master cylinder design. Each wheel cylinder can be independently actuated, allowing for individual wheel pressure control that optimizes braking distance without complicating the master cylinder mechanism
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 cost-effective, reliable, and compact braking system with consistent pedal travel characteristics, improved redundancy, and precise control of braking pressure, reducing braking distances and enhancing safety by decoupling the pedal from system failures and allowing for efficient recuperation control.
Implementation Method 1
an electric motor with a direct movement of a master cylinder piston into the brake circuit
Implementation Method 2
allowing independent control of each axle and precise pedal characteristics, and redundant power supplies, enabling efficient pressure modulation
Data Source
Figure 1
Figure 1a~2
Figure 3
AI summary
The inventions relate to a brake system comprising: - an actuation device (1), in particular a brake pedal, - a first piston-cylinder unit (TH2) with two pistons (12, 16), in particular an auxiliary piston (16) and a second piston (12), in order to supply brake circuits (Bk1, Bk2) with a pressure medium via a valve device, wherein one of the pistons (16), in particular the auxiliary piston, can be actuated by means of the actuation device (1), - a second piston-cylinder unit (25) comprising an electric motor-powered drive (8), a transmission, and at least one piston (10) in order to supply pressure medium to at least one of the brake circuits (Bk1) via a valve device, and - a motor pump unit (ESP) with a valve device (EV,AV, HSV,USV) in order to supply pressure medium to the brake circuits (Bk1, Bk2). According to the first invention, the brake system comprises a hydraulic travel simulator (WS) which is connected to a pressure or working chamber of the first piston-cylinder unit (TH2). According to the second invention, the brake system comprises a controller (ECU) by means of which the motor of the electric motor-powered drive (8) of the second piston-cylinder unit (25) and the motor (M) of the motor-pump unit (ESP) can be used together or independently of each other. According to the third invention, a four-wheel blending process is carried out in order to control a recuperation, wherein pressure is controlled via the piston (10) of the second piston-cylinder unit (25) when the valves of the motor-pump unit (ESP) are open. According to the fourth invention, along with the breather hole passage of a line which leads to the storage container (VB), said passage being provided with two seals (D4, D5), the cylinder of the first piston-cylinder unit (TH2) has an additional passage at the level of the second piston (12), said additional passage being provided with an additional seal (D4r) and being connected to the line leading to the storage container (VB).