Position Measuring Device Scale Base Body Connection

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Solution Overview

Problem

Existing position measuring devices face challenges in achieving precise longitudinal position measurement due to thermal expansion and vibrations, often resulting in reduced accuracy and requiring complex adjustments, especially when the scale is housed within a two-part housing.

Innovation Solution

A position measuring device design featuring a base body directly connected to a scale, with a two-part housing that allows the scanning unit to move independently, eliminating direct connections to the housing parts and enabling precise measurement by using a driver with a cable gland and adapter pieces for alignment, thus avoiding misalignment and simplifying the encapsulation process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the scale is connected to a two-part housing, then the housing can be assembled and disassembled for cleaning, but thermal expansion and vibrations cause misalignment and reduce measurement precision

Engineering Contradiction:
Improvehousing assemblyVSAvoidposition measurement accuracy
Core Design Contradiction:
Ease of manufactureVSMeasurement precision

Solution Approach 1:

The housing is divided into two separate parts that can be assembled and disassembled for cleaning, while the scale remains directly connected to the base body. This segmentation allows the housing to be maintained without affecting the scale's positioning or measurement accuracy.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The scale is extracted from the housing structure and directly connected to the base body, eliminating it from the housing's thermal and vibrational influences. This separation ensures that housing assembly/disassembly for cleaning does not affect scale alignment or measurement precision.

Inventive Principle:
Principle #2Taking out (Extraction)

2Device complexity

If the scanning unit is fixed to the housing, then the structure is simpler, but the scanning unit cannot move independently affecting measurement capability

Engineering Contradiction:
Improvestructural complexityVSAvoidscanning unit movement
Core Design Contradiction:
Device complexityVSEase of operation

Solution Approach 1:

The driver is designed with a specific cable guidance structure that allows the scanning unit to move independently along the scale while the housing remains stationary. This localized movement capability enables the scanning unit to track the scale without requiring the entire housing to move, maintaining both structural simplicity and operational flexibility.

Inventive Principle:
Principle #3Local quality

3Adaptability or versatility

If the cable is routed through the driver, then the scanning unit can be supplied with power and signals, but the driver structure becomes more complex requiring recesses and closure elements

Engineering Contradiction:
Improvecable routing capabilityVSAvoiddriver structure
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The driver features an asymmetric design with a recess on one side for cable entry and a closure element on the opposite side. This asymmetric configuration allows the cable to be routed through the driver in a straightforward manner, minimizing structural complexity while maintaining the necessary adaptability for power and signal transmission to the scanning unit.

Inventive Principle:
Principle #4Asymmetry

Data Source

PatentEP4109046B1Position measuring device
Publication Date: 2024.08.07 DR JOHANNES HEIDENHAIN GMBH
  • EP4109046B1 patent drawingFigure 1
  • EP4109046B1 patent drawingFigure 2
  • EP4109046B1 patent drawingFigure 3a~3b

AI summary

A position measuring device comprises a base body (1), a first housing part (10.1) extending in a longitudinal direction (X) and connected to the base body (1), and a second housing part (10.2) extending in a longitudinal direction (X) and connected to the base body (1). A hollow profile (10) is formed by at least the first housing part (10.1) and the second housing part (10.2). The position measuring device has a scale (12) arranged within the hollow profile (10) and a scanning unit (14) for scanning the scale (12). The base body (1) and the scale (12) are directly connected to each other.