Self-Centering Sealing Element for Length Measuring Device

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Solution Overview

Problem

Existing length measuring devices face challenges in achieving effective sealing and maintaining reproducible position measurements, especially in harsh environments, due to limitations in sealing technologies and potential interference with the measuring accuracy.

Innovation Solution

A length measuring device featuring a hollow profile with a plate-like sealing element that fills the clear width of the profile, allowing for self-centering and easy alignment, and made of flexible materials for sealing with a more rigid central area to ensure reliable sealing and maintain measuring accuracy, along with a design that accommodates compressed air for overpressure in harsh environments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a seal is inserted between the end face of the hollow profile and the end piece mounted on it, then sealing is achieved, but the sealing element may exert forces on the hollow profile affecting measuring accuracy

Engineering Contradiction:
Improvesealing effectivenessVSAvoidposition measurement accuracy
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

The patent introduces an immersion area as an intermediary element between the end piece and the hollow profile. This immersion area allows the end piece to be inserted into the hollow profile without the sealing element directly contacting and exerting forces on the hollow profile walls. The seal is formed at the end face interface, while the immersion area provides mechanical clearance, preventing measurement interference.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The sealing element is divided into functionally distinct areas: a sealing area that contacts the end face to create the seal, and an immersion area that extends into the hollow profile but does not contact the walls. This segmentation allows the sealing function to be separated from the mechanical support function, preventing force transmission to the hollow profile that would affect measurement accuracy.

Inventive Principle:
Principle #1Segmentation

2Reliability

If the sealing element is made of flexible material, then sealing conformability is improved, but structural rigidity and self-centering capability deteriorate

Engineering Contradiction:
Improvesealing conformabilityVSAvoidself-centering capability
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The sealing element features local quality differentiation with a soft, flexible sealing area that conforms to the end face surface for reliable sealing, and a rigid immersion area that provides structural strength and self-centering capability. This local quality variation allows the single component to simultaneously achieve both sealing conformability and mechanical rigidity without requiring multiple parts.

Inventive Principle:
Principle #3Local quality

3Stability of the object's composition

If the end piece is rigidly fixed to the hollow profile, then structural stability is improved, but alignment flexibility and self-centering capability deteriorate

Engineering Contradiction:
Improvestructural stabilityVSAvoidalignment flexibility
Core Design Contradiction:
Stability of the object's compositionVSEase of operation

Solution Approach 1:

The end piece is designed with dynamic characteristics through the immersion area that can move relative to the hollow profile walls during assembly. This allows the end piece to self-center as it is inserted into the hollow profile, achieving automatic alignment. Once positioned, the end piece can be secured with appropriate fastening elements, providing both initial alignment flexibility and final structural stability.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP2634538B1Length measuring device
Publication Date: 2019.01.09 DR JOHANNES HEIDENHAIN GMBH
  • EP2634538B1 patent drawingFigure 1
  • EP2634538B1 patent drawingFigure 2
  • EP2634538B1 patent drawingFigure 3~4

AI summary

The length measuring device consists of a hollow profile (3) in which a scale (1) is protected. The hollow profile (3) is closed at its end end by an end piece (5). For sealing the end end of the hollow profile (3), a plate-shaped sealing element (7) is attached to the end piece (5). The sealing element has a cross-section that corresponds at least largely to the clear width of the hollow profile (3) and bears against an inner surface (32) of the hollow profile (3) with a circumferential surface (71), sealing it there. The sealing element (7) is self-centering on the end piece (5).