Weighing Cell Sealing via Overpressure and Membrane
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Solution Overview
Problem
Existing sealing methods for load cells in the pharmaceutical industry fail to prevent residual liquid penetration during cleaning and disinfection, and do not allow for rapid cooling and measurement after the process, especially when using hot liquids and warm to hot air.
Innovation Solution
Generating a slight overpressure in the housing using cooled, filtered air and regulating its discharge after the seal is opened, which prevents residual liquid and dust from entering and allows for controlled cooling and measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a labyrinth seal is used to seal the receiver axle passage during cleaning, then the seal structure can be closed to prevent cleaning medium penetration, but the structure becomes relatively complicated and cannot prevent residual liquid penetration due to adhesion
Solution Approach 1:
The invention extracts the sealing function from the complex labyrinth seal structure and implements it through a simple membrane that selectively blocks liquid while allowing gas exchange. The membrane is a separate, simple component that replaces the complicated labyrinth seal mechanism.
Solution Approach 2:
The membrane acts as an intermediary element between the housing interior and exterior, selectively permitting certain substances (gas) while blocking others (liquid). This simple intermediary component solves the sealing problem without requiring complex structures.
2Reliability
If a bellows seal is used to seal the power transmission passage, then the housing can be sealed during cleaning, but it creates a permanent connection that acts as a force shunt affecting measurement precision
Solution Approach 1:
The invention removes the bellows seal that creates force shunting and replaces it with a membrane that seals the receiver axle passage without creating a permanent flexible connection. This eliminates the force shunt effect while maintaining sealing functionality.
3Ease of operation
If a permanently open gap is provided in the sensor axis for humidity entry, then the housing can be vented, but cleaning liquids can penetrate and quickly use up the desiccant supply
Solution Approach 1:
The membrane serves as an intermediary that allows gas (humidity) to pass through while blocking liquid penetration. This selective permeability maintains humidity venting capability while preventing cleaning liquids from entering and compromising the desiccant.
4Reliability
If hot liquids and warm to hot air are used for cleaning and drying, then cleanability and disinfection are improved, but the housing requires extended cooling time before subsequent weighing
Solution Approach 1:
The membrane allows continuous gas exchange between the housing interior and exterior, enabling continuous cooling air flow through the housing during and after cleaning. This continuous action accelerates cooling without interrupting the cleaning process or requiring extended cooling time before weighing.
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 solution effectively prevents the ingress of unwanted substances and enables rapid cooling and measurement by maintaining a controlled overpressure during and after the cleaning process without affecting the measurement results.
Implementation Method 1
a cooled gas is fed into the housing via an air inlet to generate an overpressure
Implementation Method 2
the gas is at least partially discharged from the housing via the passage of the housing after the seal has been opened
Implementation Method 3
enables rapid cooling and measurement by maintaining a controlled overpressure during and after the cleaning process
Data Source
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AI summary
The invention relates to a weighing cell (1), comprising a weighing system (4) arranged in a housing (3), a load cell (2) disposed outside the housing (3) and connected to the weighing system (4) via a supporting axis (6), and a sealing (8) by means of which the passage (7) of the housing (3) for the supporting axis (6) can be sealed during a cleaning process, wherein an air inlet (9) leading into the housing (3) is provided via which a gas can be guided into the housing (3) by means of a pressure generating device (5) for generating an over-pressure. The invention also relates to a method for sealing a weighing cell (1), comprising a weighing system (4) arranged in a housing (3), a load cell (2) disposed outside the housing (3) and connected to the weighing system (4) via a supporting axis (6), and a sealing (8) by means of which the passage (7) of the housing (3) for the supporting axis (6) can be sealed during and/or after a cleaning process as to prevent the entry of liquid and/or dirt, wherein a gas is guided via an air inlet (9) into the housing (3) for generating an over-pressure.