Isolation Valve Fail-Safe for Electrohydraulic Brake Systems
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Solution Overview
Problem
Modern electrohydraulic antilock brake systems fail to operate properly in the event of an electrical failure or controller malfunction, posing a safety hazard as they cannot convert to a purely hydraulic braking system effectively.
Innovation Solution
Incorporating a normally open isolation valve that shifts to an open position in the event of a loss of electrical current, allowing pressurized hydraulic fluid to bypass the electrohydraulic components and enable the brake system to function in a purely hydraulic manner, ensuring continued operation during electrical failures or controller malfunctions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an electrohydraulic antilock brake system is used to improve braking control precision, then wheel slippage can be limited to a safe level, but the system fails to operate properly in the event of an electrical failure or controller malfunction
Solution Approach 1:
The isolation valve serves as an intermediary component that mediates between the electrohydraulic control system and the purely hydraulic brake system. During normal operation, the valve remains closed, allowing the electrohydraulic system to provide precise wheel deceleration monitoring and control. Upon detection of electrical failure or controller malfunction, the valve automatically opens, switching the system to a purely hydraulic mode and ensuring continued brake operation despite the loss of electronic control functions.
Solution Approach 2:
The system changes its operational parameter state based on electrical system integrity. When electrical power and controller functions are normal, the isolation valve is closed, enabling electrohydraulic operation with precise electronic monitoring of wheel deceleration. When electrical failure or controller malfunction is detected, the isolation valve opens, transitioning the system to a purely hydraulic operational state, thereby adapting the system's functional parameters to match the available resources and maintain reliability.
2Productivity
If electrohydraulic components are added to enable antilock braking control, then braking performance is improved, but system complexity increases and safety hazards arise from electrical failures
Solution Approach 1:
The brake system is segmented into two distinct operational modes: an electrohydraulic mode for normal operation with precise antilock control, and a purely hydraulic mode for failure conditions. The isolation valve acts as the segmentation boundary, physically separating the electrohydraulic control circuit from the hydraulic brake actuation circuit. This segmentation allows the system to enjoy the benefits of electrohydraulic control when available while maintaining a simple, reliable hydraulic backup that can operate independently of the complex electronic systems.
3Reliability
If the isolation valve is designed to be normally open for automatic fail-safe operation, then reliability under electrical failure is improved, but the electrohydraulic system cannot function during normal operation
Solution Approach 1:
Instead of designing a normally open isolation valve that would ensure fail-safe operation but prevent normal electrohydraulic function, the patent inverts the approach by using a normally closed valve that is actively held closed during normal operation. The valve is designed to fail open upon loss of electrical power or controller malfunction, thereby achieving both goals: maintaining antilock braking functionality during normal operation while ensuring automatic fail-safe operation during electrical failures. This inversion of the default valve state resolves the contradiction between normal operation productivity and failure condition 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 design enhances the safety of antilock brake systems by providing a reliable means to convert from an electrohydraulic to a hydraulic system, reducing the risk of system failure and maintaining braking functionality even in the absence of electrical power.
Implementation Method 1
The isolation valve may also be linked to the controller which may maintain the isolation valve in a closed position during normal operating conditions by supplying current to the isolation valve. The isolation valve may shift to an open position in the event current supplied by the controller is interrupted.
Data Source
AI summary
An antilock brake system for a vehicle may include a controller that is linked to a brake pedal sensor. The brake pedal sensor may be linked to a brake pedal. The brake pedal may be coupled to a normally closed brake pedal valve. The brake pedal valve may include an inlet in communication with a source of pressurized hydraulic fluid and an outlet in communication with a normally opened isolation valve. The isolation valve may be in communication with one or more main control valve systems and may be linked to a controller which maintains the isolation valve in a closed position during normal operating conditions. The isolation valve then shifts to an open position in the event current supply by the controller is interrupted as a result of an electrical failure or malfunction of the controller.