Nested Clean Chamber Filtration for Stable Positive Pressure
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Solution Overview
Problem
Conventional mini environment structures in clean chambers rely on a single filtration by a fan filter unit (FFU), making cleanliness dependent on external environment conditions, which can lead to insufficient cleanliness if external disturbances occur.
Innovation Solution
A mini environment apparatus with a clean chamber maintained at positive pressure by an inner FFU, independent of the external FFU, ensures higher cleanliness by filtering air within the chamber through double dust collecting filters before entering the clean chamber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If air is fed from external environment through a single FFU, then device complexity is reduced, but cleanliness reliability deteriorates
Solution Approach 1:
The air supply system is segmented into two independent FFUs: an outer FFU for the semi-clean chamber and an inner FFU for the clean chamber. This segmentation allows each FFU to independently control its respective chamber's cleanliness, ensuring that the clean chamber maintains target cleanliness even if the external environment or outer FFU performance degrades.
Solution Approach 2:
The clean chamber is nested within the semi-clean chamber, and the inner FFU is positioned within the clean chamber. This nested structure enables the inner FFU to draw air from the semi-clean chamber and filter it further, creating a hierarchical cleanliness control system where the inner chamber benefits from both the outer chamber's filtered air and its own additional filtration.
2Ease of manufacture
If single FFU filtration is used, then ease of manufacture is improved, but manufacturing precision deteriorates
Solution Approach 1:
The manufacturing system is divided into two independent air supply units (outer FFU and inner FFU), each responsible for a specific chamber. This segmentation allows each unit to be manufactured and tested independently, simplifying the overall manufacturing process while achieving higher precision cleanliness control through the combined effect of two filtration stages.
3Use of energy by moving object
If positive pressure is maintained by single FFU, then energy consumption is reduced, but cleanliness stability deteriorates
Solution Approach 1:
The pressure control system is segmented into two independent positive pressure maintenance systems, each operated by its own FFU. This allows each chamber to maintain its positive pressure independently, ensuring that cleanliness stability in the inner chamber is not compromised by fluctuations in the outer chamber's pressure or air supply.
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 effectively suppresses the influence of external environment cleanliness, maintaining target cleanliness within the specific space by ensuring the clean chamber operates at a more positive pressure than the semi-clean chamber, even in less-than-ideal airtight conditions.
Implementation Method 1
a fan filter unit, so as to feed an air within the casing to the clean chamber
Implementation Method 2
keeping an inner side of the clean chamber at a more positive pressure with respect to the space within the casing
Data Source
AI summary
An outer dust collecting filter covers a casing an intake port and an outer fan flows air from an external environment into the casing via the outer dust collecting filter. A clean chamber has an intake port within the casing, an inner dust collecting filter for covering the intake port, and an inner fan for flowing the air within the casing. A control unit controls fan rotating speeds so that a measured pressure within the casing becomes higher at a set value than a measured pressure in the external environment, and a measured pressure within the clean chamber becomes higher at a set value than the measured pressure within the casing.