Rotary Viscometer Gap Calibration for Accurate Hot Sample Testing

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Solution Overview

Problem

Existing rotary viscosimeters suffer from manual gap setting errors, especially under thermal conditions, leading to viscosity measurement inaccuracies.

Innovation Solution

A method and device utilizing an adjusting drive to automate the setting of the measuring gap between the spindle and measuring cup, accompanied by a correction table to account for manufacturing tolerances and thermal expansion, and a spindle extraction mechanism to handle hot parts safely.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If manual setting of the measuring gap is used, then the device construction remains simple, but measurement precision deteriorates due to user error and susceptibility to thermal conditions

Engineering Contradiction:

Improveviscosity measurement accuracyVSAvoidadjusting drive mechanism

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The control unit automatically determines the measuring gap based on stored reference values and thermal expansion coefficients, eliminating the need for manual adjustment by the user. The system self-regulates the gap setting based on temperature conditions, thereby improving measurement precision without requiring complex manual intervention mechanisms.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent replaces manual mechanical adjustment with an automated control system that uses stored reference values and thermal expansion calculations to determine the optimal measuring gap. This substitution of mechanical manual operation with automated control improves precision while keeping the physical adjusting drive mechanism relatively simple.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If manual setting of the measuring gap is used, then the device construction remains simple, but reliability deteriorates under special thermal conditions

Engineering Contradiction:

Improvemeasurement consistency under thermal conditionsVSAvoidautomated gap adjustment system

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The control unit automatically compensates for thermal expansion effects by retrieving reference values stored during calibration and applying thermal expansion coefficient calculations. This self-service approach ensures consistent reliable measurements under varying thermal conditions without requiring complex real-time sensor systems or manual intervention.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

Reference values for the measuring gap are predetermined and stored in the control unit during calibration at specific temperatures. These pre-stored values are then retrieved and applied during actual measurements, allowing the system to anticipate and compensate for thermal effects without requiring complex real-time adjustment mechanisms.

Inventive Principle:

Principle #10Preliminary action

3Measurement precision

If dimensional tolerances of measuring parts are not compensated, then manufacturing remains simple, but measurement precision deteriorates due to gap deviations

Engineering Contradiction:

Improveviscosity value accuracyVSAvoidmeasuring part dimensional tolerance

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent replaces strict mechanical dimensional tolerance control with a software-based compensation system. The control unit stores reference values determined during calibration and uses these along with thermal expansion coefficients to calculate the actual measuring gap, thereby compensating for manufacturing variations without requiring ultra-precise manufacturing processes.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system incorporates feedback through stored reference values that capture the actual dimensions of specific measuring part pairings. During measurement, the control unit retrieves these reference values and applies corrections based on thermal expansion calculations, creating a feedback loop that compensates for dimensional tolerances and improves measurement accuracy.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS20260009712A1Method for ascertaining the viscosity of a sample using a rotary viscosimeter

Publication Date: 2026.01.08 ANTON PAAR GMBH

AI summary

A method ascertains the viscosity of a sample using a rotary viscosimeter. A measuring body is arranged on a measuring shaft, and a second measuring part is arranged on the rotary viscosimeter. The distance between the measuring body and the second measuring part is reduced until a flow can pass between the measuring body and the second measuring part, thus defining a zero distance between the measuring body and the second measuring part. The distance between the measuring body and the second measuring part is increased from the zero distance such that a defined measuring gap is set. The second measuring part is removed, a sample is introduced into the second measuring part, and the second measuring part is repositioned. A viscosity measurement is carried out on the sample, and the viscosity of the sample is determined by an analysis unit.