Parallel-Guided Coupling for Calibration Weight Force Transmission

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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 transmission to the measuring sensor, leading to inaccurate correction values due to small deviations in calibration weight placement and lever arm geometry.

Innovation Solution

A force transmission device with a parallel-guided coupling mechanism that includes a calibration lever with two arms and a coupling means, where only compressive or tensile forces are transmitted, allowing for precise calibration by compensating transverse movements and maintaining consistent geometric relationships, thus minimizing the impact of geometric deviations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If a calibration weight is placed on a calibration weight arm coupled to the load-receiving area, then the mass of the calibration weight can be kept small, but small deviations in calibration weight placement lead to incorrect correction values due to extended or shortened effective lever arms

Engineering Contradiction:
Improvemass of calibration weightVSAvoidcorrection value accuracy
Core Design Contradiction:
Quantity of substanceVSMeasurement precision

Solution Approach 1:

A parallel-guided coupling means is introduced as an intermediary component between the calibration lever and the load-receiving area. This coupling means includes a parallel-guided sub-coupling means and a fixed sub-coupling means that are aligned to transmit only compressive or tensile forces, preventing transverse movements from affecting the calibration weight placement accuracy and ensuring consistent force transmission to the measuring sensor.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Device complexity

If the calibration weight arm is always coupled to the load-carrying area, then the structure is simplified, but the calibration weight force transmission is affected by changing geometric conditions

Engineering Contradiction:
Improvestructure complexityVSAvoidcalibration weight force transmission accuracy
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The parallel-guided coupling means is designed to dynamically adapt to geometric changes while maintaining consistent force transmission. The parallel-guided sub-coupling means can move relative to the fixed sub-coupling means along a defined path, allowing the system to compensate for changing geometric conditions during calibration without sacrificing force transmission accuracy.

Inventive Principle:
Principle #15Dynamics

3Measurement precision

If points of contact between calibration weight and calibration weight arm or knife-edge bearing are manufactured with greatest precision, then measurement accuracy is improved, but manufacturing cost increases

Engineering Contradiction:
Improvemeasurement accuracyVSAvoidmanufacturing cost
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

The parallel-guided coupling means changes the geometric parameters of the force transmission path by introducing parallel guidance elements. This allows standard manufacturing tolerances to be sufficient because the parallel-guided sub-coupling means compensates for minor deviations through its guided movement, eliminating the need for ultra-precise manufacturing of contact points while maintaining measurement accuracy.

Inventive Principle:
Principle #35Parameter changes

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 ensures accurate calibration by balancing relative transverse movements and maintaining consistent force transmission, reducing bending moments and improving measurement accuracy in both EMFC and string load cells.

Implementation Method 1

The parallel-guided coupling means is divided into two parts, a fixed sub-coupling means and a parallel-guided sub-coupling means, which are aligned with one another in such a way that only a compressive or tensile force can be transmitted between them

Methodology Applied
Scientific EffectForce transmission: Mechanical Force

Implementation Method 2

The calibration lever includes a first and a second calibration lever arm, the parallel guided coupling means being arranged between the second calibration lever arm of the calibration lever and the at least one coupling element or a lever arm of the at least one lever

Methodology Applied
Scientific EffectLever mechanism: Lever

Implementation Method 3

The parallel-guided partial coupling means comprises a first and a second parallel element, which are arranged parallel to one another and via which the parallel-guided partial coupling means is fixed either on the second calibration arm or on the load-receiving area, on the coupling element or on the lever arm, so that relative transverse movements occur during force transmission through the parallel-guided coupling means are balanced by the first and second parallel element

Methodology Applied
Scientific EffectParallel guidance: Geometry

Data Source

PatentEP2434264B1Power transmission device with attachable calibration weight
Publication Date: 2014.04.02 METTLER TOLEDO GMBH
  • EP2434264B1 patent drawingFigure 1
  • EP2434264B1 patent drawingFigure 2
  • EP2434264B1 patent drawingFigure 3

AI summary

The power transmission device (110) has a fixed area (111) and a load-receiving area (112) which is directly connected with a measuring feeder through a coupling element (119) and a lever (116) in a power transmitting manner. The measuring feeder is arranged at the fixed area. The power transmitting device has a parallel-guided coupling unit (124) and a calibrating lever (120) with a hinge point and two calibrating lever arms (121,122). An independent claim is also included for a gravimetric measuring instrument with a weight.