Electropneumatic Brake Venting for Fail-Safe Spring Brake Activation

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Solution Overview

Problem

Existing electropneumatic braking systems in vehicles lack a reliable fail-safe braking function with minimal equipment complexity, particularly in the event of a fault or power failure, and require improvements to ensure safe vehicle stopping without additional pressure application.

Innovation Solution

The method involves interrupting the control signal to vent the spring-loaded brake cylinder using the service brake system, triggering a fail-safe braking function through the parking brake system, utilizing existing brake system structures and components to minimize additional equipment. This includes using a service brake venting function to vent the spring-loaded brake cylinder, which is then locked in to maintain braking, and employing existing valves like outlet valves and ABS valves for rapid venting.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a fail-safe braking function is implemented using additional dedicated valves and control units, then the reliability of fail-safe braking is improved, but the device complexity increases

Engineering Contradiction:
Improvereliability of fail-safe brakingVSAvoidequipment complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent makes existing brake system components (service brake valves, parking brake valves, control units) perform dual functions: their primary function plus fail-safe braking function. The service brake system vents spring brake pressure to trigger fail-safe braking, while the parking brake system provides the actual fail-safe braking action, eliminating the need for dedicated fail-safe braking components.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The existing brake system components serve themselves to provide fail-safe functionality. The control unit monitors its own operational status and automatically triggers fail-safe braking when faults are detected, without requiring separate monitoring systems. The service brake system automatically vents pressure when control signal is lost, providing self-activating fail-safe function.

Inventive Principle:
Principle #25Self-service

2Speed

If rapid venting of spring-loaded brake cylinder is achieved using existing valves, then the stopping speed is improved, but the control precision may be compromised

Engineering Contradiction:
Improvestopping speedVSAvoidcontrol precision
Core Design Contradiction:
SpeedVSManufacturing precision

Solution Approach 1:

The patent dynamically adjusts the venting process by initially opening the service brake valve fully for rapid pressure release, then transitioning to controlled venting as the spring brake pressure decreases. The control unit monitors pressure levels and modulates valve opening accordingly, providing both rapid initial response and precise controlled venting.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The venting process is executed in periodic stages: initial rapid venting phase to quickly reduce pressure, followed by controlled venting phases to maintain precision. The control unit activates venting in discrete control cycles, adjusting valve position in steps rather than continuous adjustment, which simplifies control while maintaining effectiveness.

Inventive Principle:
Principle #19Periodic action

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 provides a reliable fail-safe braking function with minimal additional equipment, ensuring rapid vehicle stopping by venting the spring-loaded brake cylinder, maintaining braking pressure even after spring-loaded pressure falls, and utilizing existing valves for efficient venting, thus enhancing safety and reducing complexity.

Implementation Method 1

at least one spring-loaded brake cylinder (442)

Methodology Applied
Scientific EffectSpring pressure: Spring

Implementation Method 2

venting of the spring-loaded brake pressure is carried out by a service brake venting function (FBE) of the service brake system

Methodology Applied
Scientific EffectPressure venting: Depressurisation

Data Source

PatentEP4396049B1Method for operating an electropneumatic brake system, fail-safety valve unit, electropneumatic brake system and vehicle
Publication Date: 2025.07.09 ZF CV SYST GLOBAL GMBH
  • EP4396049B1 patent drawingFigure 1
  • EP4396049B1 patent drawingFigure 2A~2C
  • EP4396049B1 patent drawingFigure 2D

AI summary

The invention relates to a method for operating an electropneumatic brake system (204) for a vehicle (200), preferably a utility vehicle (202), wherein the brake system (204) comprises a service brake system (510) and a parking brake system (520), wherein the parking brake system (520) comprises at least one spring brake cylinder (442). According to the invention, the following steps are provided: providing a control signal (S1, S2) for maintaining a spring accumulator ventilating pressure (pFS), which ventilates the at least one spring brake cylinder (442), by means of a control unit (410, 420), interrupting the provision of the control signal (S1, S2) in a fault situation (FF) and/or a power failure (FS) and/or a diagnostic situation (FT) of the control unit (410, 420), thereby automatically ending the maintaining of the spring accumulator ventilating pressure (pFS) for venting the at least one spring brake cylinder (442), and thereby triggering a spring accumulator failure braking operation (BAF) of the vehicle (200) by means of the parking brake system (520), wherein the spring accumulator ventilating pressure (pFS) is vented by a service brake venting function (FBE) of the service brake system (510).