Method of operating an electropneumatic parking brake system and electropneumatic parking brake system

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Solution Overview

Problem

Existing electropneumatic parking brake systems in vehicles, particularly commercial vehicles, struggle with slow transition from a completely released state to a state with braking effect, necessitating a method to enhance the speed of engaging the spring brake.

Innovation Solution

The method involves subjecting spring brake cylinders to a spring brake holding pressure lower than the reservoir pressure, typically 1 to 5 bar below, ensuring a smaller air mass to be moved during venting, and utilizing a pressure-limiting or pressure-regulating valve arrangement to achieve rapid engagement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the spring brake cylinders are subjected to the full reservoir pressure, then the spring brake can be fully released, but the time required to activate the spring brake increases due to the large air mass to be moved

Engineering Contradiction:
Improvespring brake release reliabilityVSAvoidspring brake activation time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The system pre-charges the spring brake cylinders to a reduced holding pressure (1-5 bar below reservoir pressure) while maintaining the brake in the released state. This preliminary action reduces the air mass that needs to be evacuated during activation, enabling faster response time while still ensuring reliable brake release when needed.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The invention changes the pressure parameter from the full reservoir pressure to a reduced holding pressure range. By adjusting the holding pressure to be 1-5 bar below the reservoir pressure, the system optimizes the balance between brake release reliability and activation speed, reducing the pressure differential that must be overcome during venting.

Inventive Principle:
Principle #35Parameter changes

2Loss of time

If the spring brake holding pressure is reduced to speed up activation, then the activation time decreases, but the risk of unintended brake engagement increases

Engineering Contradiction:
Improvespring brake activation timeVSAvoidbrake system stability
Core Design Contradiction:
Loss of timeVSReliability

Solution Approach 1:

The system incorporates feedback mechanisms through the electropneumatic control module that continuously monitors pressure conditions and system state. This feedback ensures that the reduced holding pressure is maintained within safe parameters and prevents unintended brake engagement by verifying that venting is intentionally initiated before activating the spring brake.

Inventive Principle:
Principle #23Feedback

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 approach significantly reduces the time required to activate the spring brake, providing a faster transition from a released state to a braking state, enhancing safety by minimizing the risk of unintended vehicle movement during uncoupling.

Implementation Method 1

the spring brake cylinders are subjected to a spring brake holding pressure pH as the output pressure pA, which is lower than a reservoir pressure pV

Methodology Applied
Scientific EffectPressure difference: Pressure Gradient

Data Source

PatentEP4304904B1Method of operating an electropneumatic parking brake system and electropneumatic parking brake system
Publication Date: 2025.09.10 ZF CV SYST GLOBAL GMBH
  • EP4304904B1 patent drawingFigure 1
  • EP4304904B1 patent drawingFigure 2
  • EP4304904B1 patent drawingFigure 3

AI summary

The invention relates to a method for operating a parking brake system (FSY) having spring-loaded brake (FSB) and control module (EH, AM), in a motor vehicle (ZG) or trailer vehicle (AG), in which the control module (EH, AM) is connected to a parking brake circuit (BK3, BK4), the parking brake circuit (BK3, BK4) is supplied with reservoir pressure (pV), and spring-loaded brake cylinders (FBA, FBZ) are acted upon by a spring-loaded holding pressure (pH) in order to adopt a release position of the spring-loaded brake (FSB), and wherein the spring-loaded brake cylinders (FBA, FBZ) are acted upon by a spring-loaded holding pressure (pH) which is lower than the reservoir pressure (pV) in the parking brake circuit (BK3, BK4).