Brake Slack Adjuster Clutch Layout for Stronger Wear Compensation

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Solution Overview

Problem

Conventional automatic slack adjusters for vehicle brakes face challenges with complex designs, stress on components, and difficulties in manufacturing and repair due to the small size of one-way clutch components, which affects their strength and reliability.

Innovation Solution

The automatic slack adjuster locates the one-way clutch along the axis of the driving worm screw, allowing for larger component sizes that simplify design, manufacturing, and repair, while reducing stress on the control worm wheel, and incorporates a wear adjustment mechanism with a spring and gear system for robust performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the one-way clutch is located along the axis of the control worm screw, then the clutch components can be made larger and stronger, but the design becomes more complex and places undue stress on the control worm wheel

Engineering Contradiction:
Improveclutch component strengthVSAvoidslack adjuster design complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The patent relocates the one-way clutch from the control worm screw axis to the driving worm screw axis, utilizing a different spatial dimension and arrangement. This dimensional change allows the clutch components to be larger and stronger while distributing stresses more effectively through the gear train, avoiding the complexity and stress concentration issues of the conventional arrangement.

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

2Volume of stationary object

If the control worm screw is made small to fit within the housing, then the overall device size is reduced, but the clutch components become too small for easy design, manufacturing, and repair

Engineering Contradiction:
Improvehousing volumeVSAvoidclutch component manufacturability
Core Design Contradiction:
Volume of stationary objectVSEase of manufacture

Solution Approach 1:

By moving the clutch to the driving worm screw axis, the patent creates a different spatial arrangement where clutch components can be made larger without increasing the overall housing volume. This dimensional reconfiguration allows for larger, more manufacturable clutch components while maintaining compact device dimensions through optimized space utilization.

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

3Ease of repair

If the one-way clutch components are made larger, then design, manufacturing, and repair become easier, but the device occupies more space and may increase stress on other components

Engineering Contradiction:
Improveclutch component serviceabilityVSAvoidslack adjuster volume
Core Design Contradiction:
Ease of repairVSVolume of stationary object

Solution Approach 1:

The patent achieves larger clutch components by relocating them to the driving worm screw axis, utilizing a different spatial dimension. This reconfiguration allows larger components that are easier to service while maintaining compact overall device volume through optimized arrangement of the gear train and clutch elements.

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

Solution Approach 2:

The patent divides the slack adjuster into distinct functional segments: the driving worm screw assembly with clutch, the control worm screw assembly, and the gear train. This segmentation allows the clutch components to be larger and more accessible for repair while the overall device remains compact through efficient modular arrangement.

Inventive Principle:
Principle #1Segmentation

4Reliability

If conventional slack adjuster designs are used, then the basic function is achieved, but the design is overly complex and places undue stress on the control worm wheel

Engineering Contradiction:
Improvebrake actuation reliabilityVSAvoidwear adjustment mechanism complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent simplifies the overall design by relocating the one-way clutch to the driving worm screw axis, which redistributes mechanical stresses more favorably. This dimensional change reduces undue stress on the control worm wheel while maintaining reliable brake actuation, resulting in a less complex but equally reliable design.

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 enhances the strength and reliability of the slack adjuster, simplifies assembly, and maintains consistent performance by allowing for larger clutch components and reduced stress on the control worm wheel, improving the overall efficiency of brake actuation and wear compensation.

Implementation Method 1

a spring configured to apply a biasing force to the first shaft portion of the driving worm screw

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Implementation Method 2

a wrap spring engaging surfaces of the control worm wheel and the clutch ring

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP3969777B1Automatic slack adjuster
Publication Date: 2023.12.20 BENDIX COMMERCIAL VEHICLE SYSTEMS LLC
  • EP3969777B1 patent drawingFigure 1
  • EP3969777B1 patent drawingFigure 2~3
  • EP3969777B1 patent drawingFigure 4~5

AI summary

A clearance sensing vehicle brake slack adjuster includes a housing (12) coupled to a brake actuator and supporting a driving worm wheel (14) engaging the brake cam shaft and a driving worm screw (16) having a threaded portion meshed with the driving worm wheel (14) and transferring a brake actuating force, imparted by the brake actuator to the housing (12), to the driving worm wheel (14) and cam shaft. A wear adjustment mechanism (18) for the adjuster includes a control worm wheel (78) and a clutch ring (80) disposed about the driving worm screw (16) and a wrap spring (82) engaging surfaces of the control worm wheel (78) and the clutch ring (80). The control worm wheel (78) is in mesh with a control worm screw (72). The clutch ring (80) is disposed on a side of the control worm wheel (78) opposite the threaded portion of the driving worm screw (16) and includes teeth engaging corresponding teeth on the driving worm screw.