Electropneumatic Parking Brake Module With Bistable Fail-Safe Control
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Solution Overview
Problem
Existing electronically controllable pneumatic brake systems in commercial vehicles, particularly for autonomous driving, lack a simple and efficient fail-safe mechanism that ensures reliable deceleration in the event of a fault or power failure while minimizing system complexity and installation space.
Innovation Solution
An electropneumatic parking brake module with a pilot valve assembly featuring a bistable valve and a monostable holding valve, which automatically switches to release air from the control port in case of a fault or power failure, allowing independent actuation of parking brake cylinders using an additional control pressure from existing brake system components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fail-safe mechanism is implemented using dual controllers and solenoid valves, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent extracts the fail-safe function from the complex dual-controller system and implements it through a simple normally-open solenoid valve that automatically closes upon power loss or fault, providing fail-safe operation without requiring complex control logic or multiple controllers
Solution Approach 2:
The solenoid valve is designed to automatically switch to the safe state (closing the circuit) when electrical power is lost or a fault occurs, without requiring any active control signal or intervention from controllers, thus providing self-service fail-safe protection
2Reliability
If additional valves and control components are added to the brake system, then reliability is improved, but installation space and weight increase
Solution Approach 1:
The normally-open solenoid valve integrates multiple functions: it serves as the primary control element for brake activation, provides fail-safe protection upon power loss, and eliminates the need for separate safety valves or additional control components, thereby reducing overall system weight and installation space
Solution Approach 2:
The control and safety functions are merged into a single solenoid valve component, combining the advantages of electrical control with inherent fail-safe capability, thus avoiding the need for separate safety mechanisms and reducing system 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
Ensures reliable deceleration and fail-safe operation of the vehicle by maintaining control pressure at the main valve unit, even in the absence of electrical actuation, thus providing a low-complexity and space-efficient solution for autonomous vehicle braking.
Implementation Method 1
a holding valve (76) which is arranged in a control line (82) of the main valve unit (50), wherein the holding valve (76) is to maintain a control pressure (pS) in the control line (82)
Implementation Method 2
the pilot valve assembly (70) has a bistable valve (72) which is switchable between a first air admission position and a second air release position
Implementation Method 3
Each of the controllers thereby switches only one of the two conductors of the supply line of the solenoid
Data Source
AI summary
The disclosure relates to a method for operating an electropneumatic parking brake module for an electronically controllable pneumatic brake system for a vehicle, in particular a commercial vehicle, having a supply port for receiving a supply pressure, at least one parking brake port for the connection of at least one parking brake cylinder, a main valve assembly which receives the supply pressure and is configured to output a spring brake pressure at the parking brake port in dependence on a control pressure, and a pilot valve assembly which receives the supply pressure and is to provide the control pressure, wherein the pilot valve assembly has a bistable valve which can be switched between a first air admission position and a second air release position, and a control unit for providing first and second switch signals to the pilot valve assembly.