Single-Chamber Master Cylinders for High-Volume Brake Pressure
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Solution Overview
Problem
Existing brake systems with motor-driven master cylinders face challenges in efficiently actuating multiple wheel brakes, particularly in large vehicles, where the volume of pressurized fluid required is substantial, leading to the need for complex and expensive dual-chamber master cylinders.
Innovation Solution
The proposed brake system employs two single-chamber motor-driven master cylinders, each operable during normal braking modes by an electric MC drive motor, generating brake actuating pressure for corresponding pairs of wheel brakes. This configuration is supplemented by a secondary power transmission unit that includes an electric PTU motor and pump pistons, providing pressurized hydraulic fluid to the wheel brakes in both normal and backup braking modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a dual-chamber master cylinder is used to provide sufficient pressurized fluid for large vehicles, then the braking performance is improved, but the device complexity and cost increase
Solution Approach 1:
The brake system divides the master cylinder function into multiple single-chamber master cylinders (first master cylinder and second master cylinder), each serving specific wheel brakes. This segmentation allows the system to provide sufficient pressurized fluid volume without requiring a complex dual-chamber master cylinder, as each single-chamber unit can be independently sized and configured for its specific function.
2Quantity of substance
If a dual-chamber master cylinder is used to provide sufficient pressurized fluid for large vehicles, then the braking performance is improved, but the manufacturing cost increases
Solution Approach 1:
The system uses multiple single-chamber master cylinders instead of one dual-chamber unit. Single-chamber master cylinders are simpler to manufacture, have fewer sealing requirements, and are easier to assemble and maintain. This segmentation approach reduces overall manufacturing cost while achieving the necessary fluid volume for large vehicle braking requirements.
3Reliability
If motor-driven master cylinders are used to actuate multiple wheel brakes, then the braking performance is improved, but the system complexity increases
Solution Approach 1:
The system segments the motor-driven master cylinder functions into separate first and second master cylinders, each with its own electric motor and control. This segmentation allows for simpler individual units that are easier to control and maintain, while collectively providing the comprehensive braking performance needed for multiple wheel brakes in large vehicles.
Solution Approach 2:
The secondary power transmission unit serves multiple functions: it can provide pressurized fluid during normal braking operations and also serves as a backup power source in case of master cylinder or motor failure. This multi-functionality reduces the need for separate backup systems, thereby managing overall system complexity while improving reliability.
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
This configuration effectively addresses the challenge of providing sufficient pressurized fluid for large vehicles by using two single-chamber master cylinders, reducing the complexity and cost associated with dual-chamber systems while ensuring reliable braking performance in both normal and backup modes.
Implementation Method 1
Each master cylinder is operable during a normal non-failure braking mode by actuation of an electric MC drive motor of the master cylinder to generate brake actuating pressure
Implementation Method 2
generate brake actuating pressure at a respective first or second MC output for hydraulically actuating a corresponding one of the first and second pairs of wheel brakes
Implementation Method 3
The secondary power transmission unit includes an electric PTU motor configured to selectively pressurize the hydraulic fluid by transmitting rotary motion to at least two pump pistons
Implementation Method 4
Each pump piston provides pressurized hydraulic fluid to a corresponding one of the first and second PTU outputs
Data Source
AI summary
A brake system includes a reservoir and first and second motor-driven master cylinders. An electronic control unit is provided for controlling at least one of the first and second master cylinders responsive to at least one brake pressure signal. A secondary power transmission unit is configured for selectively providing pressurized hydraulic fluid at first and second PTU outputs for actuating first and second pairs of wheel brakes in at least one of a normal non-failure braking mode and a backup braking mode. Each of the first and second PTU outputs provides fluid to a corresponding one of the first and second pairs of wheel brakes. The secondary power transmission unit is directly fluidly connected to the reservoir.