Calibration Lever With Unidirectional Coupling For Gravimetric Instruments

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Solution Overview

Problem

Existing gravimetric measuring instruments face challenges in minimizing the influence of changing geometric conditions on calibration weight force, leading to error-prone correction values due to small deviations in calibration weight placement and lever arm geometry.

Innovation Solution

A force transmission device with a calibration lever and unidirectional coupling elements, where the articulation point is supported on a fixed area, allowing for precise coupling or decoupling of the calibration weight, minimizing geometric errors by transmitting forces through flexible thin-point bending bearings rather than contact points.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a calibration weight is placed directly on the load receiving area, then the calibration force is straightforward to apply, but small deviations in placement position lead to changes in lever arm geometry and introduce geometric errors

Engineering Contradiction:
Improvecalibration accuracyVSAvoidplacement precision requirement
Core Design Contradiction:
Measurement precisionVSEase of operation

Solution Approach 1:

The patent introduces a calibration lever as an intermediary component between the calibration weight and the load receiving area. The calibration lever includes a first calibration lever arm connected to the calibration weight and a second calibration lever arm connected to the load receiving area, with an articulation point that serves as a pivot. This intermediary lever system allows the calibration weight to be placed at a standardized position while still transmitting the calibration force to the load receiving area, thereby eliminating the need for precise direct placement and reducing geometric errors.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If the calibration weight is coupled permanently to the load receiving area, then the calibration lever is always positioned correctly, but the calibration weight cannot be easily removed or replaced

Engineering Contradiction:
Improvecalibration lever positioning stabilityVSAvoidcalibration weight attachability
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent implements a dynamic coupling mechanism that allows the calibration weight to be selectively attached and detached from the load receiving area. The unidirectional coupling element provides a reliable connection during calibration operations while allowing easy removal when calibration is complete. This dynamic system maintains the calibration lever in a correct position during use but enables flexible attachment and detachment of the calibration weight as needed.

Inventive Principle:
Principle #15Dynamics

3Force

If contact points are used to transmit calibration weight force, then the force transmission is direct, but bending moments and tilting forces arise due to misalignment

Engineering Contradiction:
Improvecalibration force transmissionVSAvoidbending moments and tilting forces
Core Design Contradiction:
ForceVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the traditional contact point mechanism with a lever-based mechanical system. Instead of relying on direct contact between the calibration weight and the load receiving area, the calibration lever transmits the force through its articulation point and lever arms. This substitution eliminates bending moments and tilting forces by providing a standardized force transmission path that is insensitive to small positioning variations.

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

This configuration maintains consistent geometric relationships, reducing bending moments and tilting forces, thereby enhancing the accuracy of calibration and measurement values in gravimetric measuring instruments.

Implementation Method 1

The unidirectional coupling element is divided into a first sub-coupling element and a second sub-coupling element. The first sub-coupling element is fixed to the load bearing area or to the coupling element or to the lever arm by means of a first thin point flexure bearing and the second sub-coupling element is fixed to the second calibration lever arm by means of a second thin point flexure bearing.

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP2336736B1Power transmission device with attachable calibration weight
Publication Date: 2015.04.15 METTLER TOLEDO GMBH
  • EP2336736B1 patent drawingFigure 1
  • EP2336736B1 patent drawingFigure 2
  • EP2336736B1 patent drawingFigure 3

AI summary

A force transmission device of a gravimetric measuring instrument comprises a stationary section and a load-bearing section, the latter being connected directly or by means of at least one coupling element and at least one lever to a sensor arranged on the stationary section. Furthermore, the force transmission device includes a calibration lever whose pivot point is supported on the stationary section, whose first calibration lever arm is rigidly connected to a calibration weight, and whose second calibration lever arm is connected by a unidirectional coupling element to the load-bearing section, to the at least one coupling element, or to a lever arm of the at least one lever.The unidirectional coupling element is divided into a first partial coupling element and a second partial coupling element, so that as a result of this division, only a tensile force or only a compressive force can be transmitted with the unidirectional coupling element.