Spring Brake Diaphragm Structure for Piston Pipe Isolation

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Solution Overview

Problem

The mechanical contact between a metal parking piston pipe and a rubber diaphragm in spring brake actuators leads to wear and influences the performance of the diaphragm, reducing the reliability of the braking system.

Innovation Solution

A diaphragm arrangement comprising an outer diaphragm member, an inner diaphragm member, and a piston plate, where the outer diaphragm member has a central opening covered by the inner diaphragm member and piston plate, allowing the piston pipe to interact mechanically with the inner diaphragm member and piston plate, avoiding direct contact with the rubber.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If a metal parking piston pipe directly contacts a rubber diaphragm to transmit force, then mechanical interaction is achieved, but diaphragm wear increases and reliability decreases

Engineering Contradiction:
Improveforce transmissionVSAvoiddiaphragm wear
Core Design Contradiction:
ForceVSReliability

Solution Approach 1:

The patent introduces a metal plate as an intermediary component between the metal piston pipe and the rubber diaphragm. The piston pipe contacts the metal plate, which in turn contacts the diaphragm, preventing direct metal-to-rubber contact and eliminating wear while maintaining effective force transmission through the intermediate metal-to-metal and metal-to-rubber interfaces

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If a metal plate is introduced between the piston pipe and diaphragm, then diaphragm wear is prevented, but device complexity increases

Engineering Contradiction:
Improvediaphragm wear resistanceVSAvoidnumber of components
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines the metal plate with the piston rod, forming an integrated component where the plate serves as both a protective element and a structural part of the actuation mechanism. This merging approach prevents diaphragm wear while avoiding the complexity of adding a separate, standalone component

Inventive Principle:
Principle #5Merging (Combining)

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 reduces diaphragm wear and enhances the performance of the spring brake actuator by ensuring a robust and reliable mechanical interaction without compressing the diaphragm, thereby improving the braking system's reliability.

Implementation Method 1

the outer diaphragm member is adapted to elastically deform under a mechanical actuation by the piston pipe (255) and/or of the push rod (260)

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP4650234A1Diaphragm arrangement for a spring brake actuator of a pneumatic braking system of a vehicle, in particular utility vehicle, spring brake actuator, pneumatic braking system, and vehicle
Publication Date: 2025.11.19 ZF CV SYST EURO BV
  • EP4650234A1 patent drawingFigure 1
  • EP4650234A1 patent drawingFigure 2~3
  • EP4650234A1 patent drawingFigure 4~5

AI summary

Diaphragm arrangement (100) for a spring brake actuator (250) of a pneumatic braking system (210) of a vehicle (200a), in particular utility vehicle (200b); wherein the diaphragm arrangement (100) is adapted to enable a mechanical interaction between a piston pipe (255) of the spring brake actuator (250) and a push rod (260); and the diaphragm arrangement (100) comprises an outer diaphragm member (110), an inner diaphragm member (120) and a piston plate (130), wherein the outer diaphragm member (110) is at least partially outwardly arranged from the inner diaphragm member (120) and from the piston plate (130); the piston plate (130) is adapted to be deflected together with the pushrod (260); the outer diaphragm member (110) is adapted to be mounted to a housing (251) of the spring brake actuator (250); the outer diaphragm member (110) comprises a central opening (111); the inner diaphragm member (120) and/or the piston plate (130) is arranged to cover the opening (111); and the outer diaphragm member (110), the inner diaphragm member (120) and the piston plate (130) are fixated to each other.