Evacuable Balance Housing With Column-Mounted Weighing System
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Solution Overview
Problem
Precision balances with evacuable housings face measurement uncertainties due to mechanical stresses and distortions caused by negative pressure and temperature changes during evacuation, which affect the delicate components of the weighing system.
Innovation Solution
The weighing system is mounted indirectly via a stable vertical column rising from the housing base, redirecting all deformations into purely vertical movements, minimizing horizontal stress and ensuring precise vertical application of weight force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the housing is evacuated to eliminate buoyancy effects, then measurement precision is improved, but mechanical stresses and distortions increase causing measurement uncertainties
Solution Approach 1:
A column is introduced as an intermediary element between the housing base and the weighing system base. This column acts as a mediator that decouples the weighing system from direct contact with the deforming housing base, allowing the weighing system to be isolated from mechanical stresses and distortions caused by evacuation while still maintaining the benefits of vacuum measurement.
Solution Approach 2:
The mounting structure is segmented into separate components: the housing base, the column, and the weighing system base. This segmentation allows each component to respond independently to evacuation forces, with the column serving as a stable support that does not deform with the housing base, thereby protecting the weighing system from distortion.
2Device complexity
If the weighing system is fixed directly to the housing base, then device complexity is reduced, but measurement precision deteriorates due to stress transfer
Solution Approach 1:
The column serves as an intermediary mounting element that adds minimal complexity while significantly improving measurement precision. It provides a stable, isolated mounting point for the weighing system that prevents stress transfer from the housing base without requiring complex isolation mechanisms.
3Productivity
If evacuation is performed rapidly, then productivity is improved, but temperature changes cause dimensional variations reducing measurement precision
Solution Approach 1:
The patent replaces mechanical/thermal isolation methods with a vacuum isolation approach. By evacuating the housing, thermal exchange between the weighing system and the external environment is minimized, reducing temperature-induced dimensional variations even during rapid evacuation, thereby maintaining measurement precision while improving productivity.
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 approach eliminates internal stresses within the weighing system, maintaining measurement accuracy by ensuring all components move uniformly, reducing measurement uncertainties and rapid temperature stabilization.
Implementation Method 1
Any warping of the housing base, particularly manifest as curvature, is deflected into a purely vertical movement by the column
Implementation Method 2
the actual weighing device (and of course the weight to be weighed) is placed in an airtight housing, which is evacuated before the measurement
Implementation Method 3
This can lead to changes in dimensions within the weighing system due to thermal expansion
Data Source
Figure 1
AI summary
The invention relates to a balance (10) comprising a housing (12) which can be evacuated and has a bottom (121), side walls (122) and a cover (123), and comprising a weighing device (14) which is arranged in the housing (12) and has a sample carrier (142), a weighing system (141) and a weighing sensor, wherein the weighing system (141) comprises a base which is fixed to the housing, and a load receiver which is connected to the sample carrier (142) and which is coupled both to the base, so as to be vertically movable, via a connecting-rod assembly which is hinged to the base, and coupled force-transmittingly to the weighing sensor, which is fixed to the base, via a lever assembly. The invention is characterized in that a vertical column (124) extends from the center of the bottom (121) of the housing (12), at the free end of which column the base of the weighing system (141) is fixed.