Device For Measuring The Porosity Of A Filter Element

What is this patent about?

'987 is related to the field of measuring the porosity of cylindrical filter elements, particularly those used in filter-tipped cigarettes. The background involves using encapsulation devices with elastic membranes to seal the filter and then measuring airflow to determine porosity. Existing devices have drawbacks in adjusting encapsulation length, automation, and the ability to measure both total and jacket porosity.

The underlying idea behind '987 is to use a series of independently controlled sphincter-like encapsulation modules arranged coaxially. Each module can be activated or deactivated separately, allowing for precise adjustment of the encapsulation length to match different filter lengths. This modular approach overcomes the limitations of prior art devices that rely on a single, adjustable membrane.

The claims of '987 focus on a device for measuring filter porosity that includes an encapsulating mechanism acting as a sphincter, a means for generating airflow through the encapsulated filter, and a means for measuring fluid flow parameters. Critically, the encapsulating mechanism is composed of multiple coaxial modules, each independently controllable to act as a sphincter.

In practice, each encapsulation module consists of a tubular body with an elastic membrane lining its inner wall. The space between the membrane and the wall can be pressurized or evacuated to retract or expand the membrane, effectively encapsulating the filter. By selectively activating these modules, the device can adapt to different filter lengths and perform measurements with varying degrees of encapsulation. This allows for measuring both the overall draw and the porosity of the filter jacket.

The invention differentiates itself from prior solutions by offering a more flexible and automatable approach to filter encapsulation. Instead of mechanically adjusting a single membrane, the modular design allows for electronic control of each module via electrovalves. This enables rapid and precise adjustment of the encapsulation length, facilitating automated measurement processes and enabling the determination of jacket porosity by comparing measurements with full and partial encapsulation.