Patent US4902306A successfully refreshed from Google Patents.
US4902306A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Dual-dipole electrostatic air filter
Assignee: AIR PURIFICATION PRODUCTS INTERNATIONAL PO BOX 454 ROYSE CITY TEXAS 75089 A TEXAS CORP
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Filing: 1988-08-09
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Granted: 1990-02-20
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Expires: 2008-08-09
Abstract
Abstract A filter assembly (10) for removing particulate matter from air forced therethrough comprises two pairs of oppositely charged woven electrostatic filtering material. Each pair of electrostatic filtering material comprises a positively charged and a negatively charged layer (22, 24, 28 and 30). An open cell foam layer (26) is disposed between the two pairs. Metal grids (20,32) enclose the filtering elements.
Inventors
- 👤 Gilbert W. Burnett
- 👤 Paul D. Jackson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 23:31
CPC Classifications
B; B03; B03C; B03C3/00; B03C3/02; B03C3/04; B03C3/14; B03C3/155; Y; Y10; Y10S; Y10S55/00; Y10S55/31; Y10S55/45
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
155 words
An air filter assembly comprising: a first filter pair comprising a first positively chargeable woven polypropylene electrostatic filtering element and a first negatively chargeable woven polypropylene electrostatic filtering element, said first positive and negative filtering elements being in contact with each other such that air being filtered must flow through both elements of the first filter pair; a second filter pair comprising a second positively chargeable woven polypropylene electrostatic filtering element and a second negatively chargeable woven polypropylene electrostatic filtering element, said second positive and negative filtering elements being in contact with each other such that air being filtered must also flow through both elements of the second filter pair; an open cell polyurethane foam layer disposed between said first and second filter pairs such that air being filtered must also flow through the foam layer; and first and second metal grids operable to act as grounding planes for said first and second filter pairs.
Claim 2
Dependent Claim
155 words
An air filter assembly comprising: a first filter pair comprising a first positively chargeable woven polypropylene electrostatic filtering element and a first negatively chargeable woven polypropylene electrostatic filtering element, said first positive and negative filtering elements being in contact with each other such that air being filtered must flow through both elements of the first filter pair; a second filter pair comprising a second positively chargeable woven polypropylene electrostatic filtering element and a second negatively chargeable woven polypropylene electrostatic filtering element, said second positive and negative filtering elements being in contact with each other such that air being filtered must also flow through both elements of the second filter pair; an open cell polyurethane foam layer disposed between said first and second filter pairs such that air being filtered must also flow through the foam layer; and first and second metal grids operable to act as grounding planes for said first and second filter pairs.
Claim 3
Dependent Claim
24 words
The air filter assembly of claim 1 wherein said open cell polyurethane foam layer has a thickness of at least one-quarter of an inch.
Claim 4
Dependent Claim
27 words
The air filter assembly of claim 1 wherein said open cell polyurethane foam layer is operable to develop an electrostatic charge in response to air flow therethrough.
Claim 5
Independent Claim
113 words
A method of filtering air comprising the steps of: filtering air through a first positively charged woven polypropylene electrostatic filtering element and a first negatively charged woven polypropylene electrostatic filtering element adjacent said first positively charged woven polypropylene electrostatic filtering element; filtering the air through an open cell polyurethane foam layer after said steps of filtering the air through said first positively charged and said first negatively charged electrostatic filtering elements; and filtering air through a second positively charged woven polypropylene electrostatic filtering element and a second negatively charged woven polypropylene electrostatic filtering element adjacent said first positively chargeable woven polypropylene electrostatic filtering element after filtering the air through said polyurethane foam layer.
Claim 6
Independent Claim
113 words
A method of filtering air comprising the steps of: filtering air through a first positively charged woven polypropylene electrostatic filtering element and a first negatively charged woven polypropylene electrostatic filtering element adjacent said first positively charged woven polypropylene electrostatic filtering element; filtering the air through an open cell polyurethane foam layer after said steps of filtering the air through said first positively charged and said first negatively charged electrostatic filtering elements; and filtering air through a second positively charged woven polypropylene electrostatic filtering element and a second negatively charged woven polypropylene electrostatic filtering element adjacent said first positively chargeable woven polypropylene electrostatic filtering element after filtering the air through said polyurethane foam layer.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-02-19 | 1993-08-21 | 1994-02-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-02-19 | 1997-08-21 | 1998-02-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-02-19 | 2001-08-21 | 2002-02-20 | $7700.00 | Window Closed / Lapsed |