Multi-Stage Master Cylinder for Stable Fallback Brake Pressure
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Solution Overview
Problem
Existing electronic brake systems face challenges in stabilizing braking pressure generation, particularly in fallback modes where component failures occur, leading to potential safety risks.
Innovation Solution
A master cylinder with a multi-stage bore design, featuring a first and second master piston with a pedal simulator in between, which provides a reaction force to the brake pedal and stabilizes braking pressure by adjusting the cross-sectional areas of the pistons and the inner diameters of the chambers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an electronic brake system with hydraulic pressure supply device is used to implement various braking functions, then braking functionality and control precision are improved, but system complexity increases and reliability decreases when electrical components fail
Solution Approach 1:
The master cylinder is divided into two independent master chambers (first master chamber and second master chamber) that can operate independently. Each chamber has its own master piston and can generate hydraulic pressure separately, allowing the system to function even if one chamber fails due to electrical component failure.
Solution Approach 2:
The cross-sectional areas of the first and second master pistons are designed with different values (first piston area > second piston area). This parameter differentiation allows each chamber to generate different hydraulic pressures based on the same pedal force, enabling diverse braking functions while maintaining reliability through independent operation.
2Reliability
If a multi-stage bore design with dual master chambers is implemented, then braking pressure stability in fallback mode is improved, but device complexity increases
Solution Approach 1:
Two master chambers are merged into a single master cylinder body, sharing common structural elements such as the cylinder block, seal structures, and return springs. This integration reduces the overall number of separate components while maintaining the independent pressure generation capability of each chamber.
Solution Approach 2:
The master cylinder structure serves multiple functions: it generates hydraulic pressure under normal electrical control operation, provides fallback braking capability through independent chamber operation, and offers progressive braking through differential piston areas. This multi-functionality reduces the need for separate backup systems.
3Ease of operation
If the cross-sectional area of the first master piston is made larger than the second master piston, then braking pressure distribution and pedal feel are improved, but manufacturing precision requirements increase
Solution Approach 1:
Different cross-sectional areas are assigned to the first and second master pistons based on their specific functional requirements. The first piston has a larger area for primary braking force generation, while the second piston has a smaller area for supplemental pressure. This localized differentiation optimizes pedal feel and pressure distribution while allowing each piston to be manufactured to appropriate tolerances for its specific function.
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 achieves miniaturization and lightweight of the brake system while ensuring stable braking pressure in fallback modes, reducing the risk of safety failures and enhancing overall system reliability.
Implementation Method 1
a first master piston provided to move in connection with an operation of a brake pedal and to pressurize the first master chamber
Implementation Method 2
a second master piston provided to be displaceable by a displacement of the first master piston or a hydraulic pressure in the first master chamber and to pressurize the second master chamber
Implementation Method 3
a pedal simulator interposed between the first master piston and the second master piston to provide a reaction force to the brake pedal
Data Source
AI summary
The present disclosure relates to a master cylinder and an electronic brake system having the same. The master cylinder includes a cylinder block having a bore of a multi-stage form in a longitudinal direction therein, a first master chamber and a second master chamber sequentially arranged in series in the bore, a first master piston provided to move in connection with an operation of a brake pedal and to pressurize the first master chamber, a second master piston provided to be displaceable by a displacement of the first master piston or a hydraulic pressure in the first master chamber and to pressurize the second master chamber, and a pedal simulator interposed between the first master piston and the second master piston to provide a reaction force to the brake pedal, wherein a cross-sectional area of the first master piston is provided to be relatively larger than a cross-sectional area of the second master piston.