3/2-Way Brake Valve Layout for Fail-Safe Hydraulic Pressure Control
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Solution Overview
Problem
Existing hydraulic actuation systems in braking systems face challenges in ensuring fail-safe operation and cost-effectiveness, particularly due to high safety requirements for valve failure which can affect braking performance and pedal characteristics.
Innovation Solution
The use of a double-stroke piston pump with 3/2-way valves and redundant safety features, allowing hydraulic fluid delivery during forward and return strokes, and incorporating a 3/2-way valve to connect each working chamber to a reservoir, ensuring pressure regulation even in the event of circuit failure, and utilizing a safety shut-off valve to prevent leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a 3/2-way valve is used to connect brake circuit to pressure supply device or tandem master brake cylinder, then the number of valves is reduced by one, but safety requirements for valve failure become more critical
Solution Approach 1:
The patent introduces a check valve that automatically closes in case of 3/2-way valve failure, preventing hydraulic fluid leakage from the brake circuit to the atmosphere. This beforehand cushioning mechanism ensures that even if the 3/2-way valve fails in an open position, the brake system maintains its pressure and braking function, thus addressing the safety concerns while keeping the valve count reduced
2Productivity
If a double-stroke piston is used for pressure supply, then hydraulic fluid can be delivered during forward and return strokes, but the system requires precise pressure regulation control
Solution Approach 1:
The patent incorporates a pressure sensor that continuously monitors the hydraulic pressure in the brake circuit and provides feedback to the control unit. The control unit adjusts the double-stroke piston's operation based on this feedback, enabling precise pressure regulation despite the bidirectional fluid delivery capability of the double-stroke piston
3Reliability
If a safety shut-off valve is added to prevent leakage in case of 3/2-way valve failure, then reliability is improved, but device complexity increases
Solution Approach 1:
The check valve is designed to automatically close in case of 3/2-way valve failure without requiring external control or additional valves. The valve's own mechanical design enables it to prevent leakage passively when pressure differential changes occur, thus improving reliability while minimizing the increase in device complexity
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 provides a more fail-safe and cost-effective solution with precise pressure regulation, maintaining operational integrity even in the event of hydraulic circuit failure, while reducing the need for complex and costly valve designs.
Implementation Method 1
a 3/2-way valve with which the working chamber can be selectively connected in a first switching position to the reservoir and in a second switching position to a brake circuit
Implementation Method 2
the pressure supply device includes a double-stroke piston so that hydraulic fluid can be delivered during forward and return strokes
Implementation Method 3
a specific volume of a hydraulic fluid is displaced by controlled or regulated adjustment of the piston, allowing a specified pressure in a brake circuit to be set or regulated
Data Source
AI summary
In a method for operating a brake system including two hydraulic wheel brakes each assigned a switching valve, and an electrically motor-driven pressure supply device including a piston-cylinder system with a double-stroke piston, a first working chamber connected to a first brake circuit via a first hydraulic connection, and a second working chamber connected to a second brake circuit via a second hydraulic connection, at least the first or second hydraulic connection including a 3/2-way valve with which the first or second working chamber is selectively connectable hydraulically to the reservoir in a first switching position and to the first or second brake circuit, before the 3/2-way valve is switched to its second switching position where the hydraulic connection is established between the first or second working chamber and the hydraulic connection leading to the switching valves, reducing a hydraulic pressure acting at least on a valve to be switched.