Flexible Joint Assembly for Angle Measurement Tolerance Compensation

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Solution Overview

Problem

Existing angle measuring devices face significant measurement errors due to dimensional tolerances in machine parts, particularly shafts, leading to inaccuracies in rotary movement measurements.

Innovation Solution

A structural unit for an angle measuring device featuring a flexible axial joint and a flexible radial joint, combined with a self-centering assembly unit that allows for large tolerance compensation, ensuring precise alignment and minimizing eccentricity and wobbling errors through a clamping mechanism without play, wear, or lubrication.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a clamping ring presses the hub shaft against the machine part, then the angle measuring device can be mounted on the machine part, but non-negligible measurement errors occur due to dimensional deviations

Engineering Contradiction:
Improvemounting reliabilityVSAvoidmeasurement accuracy
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

The hub shaft is divided into multiple segments (first hub shaft segment, second hub shaft segment) connected by flexible joints. This segmentation allows each segment to independently accommodate dimensional deviations while maintaining the overall mounting function, thereby preserving measurement accuracy despite variations in machine part dimensions.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The flexible joints introduce controlled flexibility parameters into the hub shaft structure. By changing the rigidity parameter locally at the joint regions, the system can adapt to dimensional deviations in the machine part without transmitting these deviations to the angle measuring device, thus maintaining measurement precision while ensuring reliable mounting.

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If dimensional tolerances of the machine part are reduced to achieve high measurement accuracy, then measurement precision improves, but manufacturing complexity and cost increase

Engineering Contradiction:
Improvemeasurement accuracyVSAvoiddimensional tolerance requirement
Core Design Contradiction:
Measurement precisionVSManufacturing precision

Solution Approach 1:

The flexible joint structure enables the hub shaft to self-adjust and self-center relative to the machine part. This self-service mechanism automatically compensates for dimensional deviations without requiring external adjustment mechanisms or highly precise manufacturing, allowing the system to achieve high measurement accuracy with relaxed tolerance requirements.

Inventive Principle:
Principle #25Self-service

3Stability of the object's composition

If the hub shaft is rigidly connected to the machine part, then structural stability is improved, but eccentricity and wobbling errors increase due to dimensional tolerances

Engineering Contradiction:
Improvestructural stabilityVSAvoidmeasurement accuracy
Core Design Contradiction:
Stability of the object's compositionVSMeasurement precision

Solution Approach 1:

The hub shaft transitions from a completely rigid structure to a dynamic structure with flexible joints that can adaptively adjust to dimensional deviations. The flexible joints provide controlled compliance that maintains structural stability for mounting while allowing the necessary movement to eliminate eccentricity and wobbling errors during operation.

Inventive Principle:
Principle #15Dynamics

4Measurement precision

If flexible joints are introduced to compensate for dimensional deviations, then measurement precision is maintained, but device complexity increases

Engineering Contradiction:
Improvemeasurement accuracyVSAvoidstructural complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The flexible joints replace complex mechanical adjustment mechanisms (such as threaded adjustments, shims, or alignment devices) with a simpler elastic deformation mechanism. This substitution achieves the same function of compensating for dimensional deviations and maintaining measurement accuracy while significantly reducing structural complexity and eliminating the need for additional adjustment components.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 enhances measuring accuracy by effectively compensating for dimensional deviations, reducing measurement errors and maintaining high precision even with large tolerances, thus improving the reliability and accuracy of angle measurements.

Implementation Method 1

the first joint is designed to be flexible in the axial direction, while the second joint is designed to be flexible in the radial direction

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Data Source

PatentEP2561318B1Assembly for an angle-measuring device
Publication Date: 2013.12.11 DR JOHANNES HEIDENHAIN GMBH
  • EP2561318B1 patent drawingFigure 1
  • EP2561318B1 patent drawingFigure 2~3

AI summary

The invention relates to a assembly for an angle-measuring device, comprising a first section (1) having an angle scale (1.1) for measuring a rotary movement about an axis (Z), and a second section (2) for fastening the assembly to a machine part (4). The assembly further comprises a third section (3) which connects the first section (1) to the second section (2). The third section (3) has a first and a second joint (3.11, 3.21, 3.31; 3.11'; 3.12, 3.22, 3.32), wherein the first joint (3.11, 3.21, 3.31; 3.11') is designed to be flexible in the axial direction, and the second joint (3.12, 3.22, 3.32) is designed to be flexible in the radial direction.