Spring Brake Cylinder Indicator Using Running Nut Force Equilibrium

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Solution Overview

Problem

The manufacturing of spring brake cylinders with brake state indication capabilities is costly and labor-intensive, and existing indicators often lack visibility and require complex manufacturing steps, such as drilling longitudinal through bores, which increases costs and reduces efficiency.

Innovation Solution

A spring brake cylinder design featuring a brake state indicator with an actuation element held in a force equilibrium between an actuation spring and a return spring, where the actuation force is altered by the nut motion of the running nut, causing the indicator pin to move between hidden and extended positions, providing clear visual indication of the brake state without the need for additional space or complex manufacturing steps.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a brake state indicator with an actuation element held in force equilibrium between two springs is used, then the visibility and reliability of brake state indication is improved, but the device complexity and manufacturing effort increases

Engineering Contradiction:
Improvebrake state indication reliabilityVSAvoidindicator mechanism complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The actuation element is held in a force equilibrium between the actuation spring and return spring, allowing it to automatically indicate the brake state without requiring additional actuators or complex control mechanisms. The system uses the existing mechanical movements of the running nut to shift the force equilibrium, which in turn moves the indicator pin to show the brake state.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The running nut serves multiple functions: it actuates the brake release mechanism and simultaneously alters the actuation force on the actuation element to indicate the brake state. This integrates the indication function into the existing mechanical structure, avoiding the need for separate indication mechanisms.

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

2Ease of manufacture

If traditional indicator designs are used, then the manufacturing process is simpler, but the visibility and clarity of brake state indication is reduced

Engineering Contradiction:
Improveindicator manufacturing easeVSAvoidbrake state visibility
Core Design Contradiction:
Ease of manufactureVSDifficulty of detecting and measuring

Solution Approach 1:

The indicator pin is designed to be visually distinct and extend visibly from the housing to provide clear indication of the brake state. The design emphasizes visual detectability through the extension and positioning of the indicator pin rather than relying on color changes.

Inventive Principle:
Principle #32Color changes

Solution Approach 2:

The indicator pin extends in a direction perpendicular to the main axis of the housing, creating a visible protrusion that provides clear visual indication of the brake state from the outside of the brake cylinder.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Adaptability or versatility

If additional space is allocated for brake state indication components, then the indicator functionality is improved, but the compactness and integration of the brake cylinder is reduced

Engineering Contradiction:
Improvebrake state indication capabilityVSAvoidbrake cylinder volume
Core Design Contradiction:
Adaptability or versatilityVSVolume of moving object

Solution Approach 1:

The actuation element and indicator pin are arranged within the existing internal volume of the brake cylinder, nesting the indication mechanism within the housing rather than adding external components. The actuation element is positioned to be actuated by the running nut's movement within the available space.

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

The indicator pin extends perpendicular to the main axis of the housing, utilizing the radial dimension for indication while keeping the axial length compact. This allows clear visual indication without significantly increasing the overall volume of the brake cylinder.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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 allows for reliable and visible indication of the brake state with reduced manufacturing effort and space requirements, enhancing the functionality and cost-effectiveness of the spring brake cylinder while maintaining a compact and integrated design.

Implementation Method 1

the actuation element is axially held in a force equilibrium between an actuation spring, exerting an actuation force on the actuation element, and a return spring, exerting a return force on the actuation element

Methodology Applied
Scientific EffectForce equilibrium:

Implementation Method 2

an actuation spring, exerting an actuation force on the actuation element, and a return spring, exerting a return force on the actuation element

Methodology Applied
Scientific EffectSpring force: Spring

Implementation Method 3

a release screw with an external thread, and a running nut, configured to act against the brake spring chamber, with an internal thread movably engaging to the external thread, such that a rotational motion of the release screw results in an axial nut movement of the running nut

Methodology Applied
Scientific EffectScrew mechanism: Screw

Data Source

PatentEP3953226B1Spring brake, brake system, motor vehicle
Publication Date: 2024.01.03 ZF CV SYST EURO BV
  • EP3953226B1 patent drawingFigure 1
  • EP3953226B1 patent drawingFigure 2A~2B
  • EP3953226B1 patent drawingFigure 3A~3B

AI summary

The invention relates to a spring brake cylinder (100), in particular parking brake cylinder (101), for a brake system (800) of a motor vehicle (1000), comprising: - a brake release mechanism (110), configured to axially contract a brake spring chamber (112) against a brake spring force in a release direction (RD) from a parking position (PP) to a driving position (PD), - wherein the brake release mechanism (110) comprises a release screw (132) with an external thread (133), and a running nut (122), configured to act against the brake spring chamber (112), with an internal thread (123) movably engaging to the external thread (133), such that a rotational motion of the release screw (132) results in an axial nut movement (MN) of the running nut (122), and - a brake state indicator (120), comprising a moveably arranged indicator pin (134), configured to indicate at an external surface (140) a brake state (BS). According to the invention, the spring brake cylinder is characterized in that - the brake state indicator (120) comprises an actuation element (128), wherein the actuation element (128) is axially held in a force equilibrium (EF) between an actuation spring (124), exerting an actuation force (FA) on the actuation element (128), and a return spring (126), exerting a return force (FR) on the actuation element (128), wherein - the actuation force (FA) is altered by the nut motion (MN) of the running nut (122) such as to shift the force equilibrium (FE), resulting in an axial element movement (ME) of the actuation element (128), and - the actuation element (128) is operatively coupled to the indicator pin (134) such as to transfer the element movement (ME) to the indicator pin (134).