US4976858A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Multi-layer filter medium
Assignee: Roki Co Ltd
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Filing: 1990-02-01
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Granted: 1990-12-11
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Expires: 2010-02-01
Abstract
Abstract A filter medium comprises nonwoven fabric of a lower fiber density and filter paper of a higher fiber density, the nonwoven fabric and the filter paper being superposed in a laminated structure. The nonwoven fabric and the filter paper are disposed upstream and downstream, respectively, in a direction in which a fluid to be filtered flows. Since the nonwoven fabric of a lower density is disposed upstream and the filter paper of a higher density is disposed downstream, relatively large particles are trapped by the upstream nonwoven fabric to promote the formation of a dust cake layer on the surface of the filter paper. Such surface trapping may prevent the particles from being embedded within the filter medium, thus preventing the filter medium from being clogged therein.
Inventors
- 👤 Teruichi Kadoya
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 21:29
CPC Classifications
F; F02; F02M; F02M35/00; F02M35/02; F02M35/024; B; B01; B01D; B01D39/00; B01D39/14; B01D39/16; B01D39/1607; B01D39/1623; B01D39/18; B01D2239/00; B01D2239/04; B01D2239/0464; B01D2239/06; B01D2239/0604; B01D2239/0636; B01D2239/065; B01D2239/0668; B01D2239/12; B01D2239/1291
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
143 words
A filter medium for an oil filter or an air filter for an internal combustion engine to remove dust particles from a fluid to be filtered; said filter medium comprising a nonwoven fabric of a lower fiber density which comprises at least two layers, and a filter paper of a higher fiber density, said nonwoven fabric and said filter paper being superposed in a laminated structure, one of said layers of the nonwoven fabric, which is closer to said filter paper, having a fiber density lower than that of the other of said layers of the nonwoven fabric which is located opposite to said filter paper with respect to the one of said layers, the one of said layers being a thermally fusible layer, said nonwoven fabric and said filter paper being joined together through the thermally fusible layer of the nonwoven fabric.
Claim 2
Dependent Claim
143 words
A filter medium for an oil filter or an air filter for an internal combustion engine to remove dust particles from a fluid to be filtered; said filter medium comprising a nonwoven fabric of a lower fiber density which comprises at least two layers, and a filter paper of a higher fiber density, said nonwoven fabric and said filter paper being superposed in a laminated structure, one of said layers of the nonwoven fabric, which is closer to said filter paper, having a fiber density lower than that of the other of said layers of the nonwoven fabric which is located opposite to said filter paper with respect to the one of said layers, the one of said layers being a thermally fusible layer, said nonwoven fabric and said filter paper being joined together through the thermally fusible layer of the nonwoven fabric.
Claim 3
Dependent Claim
57 words
A filter medium according to claim 1, wherein the other of said layers has a fiber density of 0.15 to 0.25 g/cm 3 , while the one of said layers has a fiber density of 0.1 to 0.2 g/cm 3 and said filter paper has a relatively high fiber density of 0.2 to 0.3 g/cm 3 .
Claim 4
Dependent Claim
178 words
A filter which has a filter medium for an oil filter or an air filter for an internal combustion engine to remove dust particles from a fluid to be filtered; said filter medium comprising a nonwoven fabric of a lower fiber density which comprises at least two layers, and a filter paper of a higher fiber density, said nonwoven fabric and said filter paper being superposed in a laminated structure, one of said layers of the nonwoven fabric, which is closer to said filter paper, having a fiber density lower than that of the other of said layers of the nonwoven fabric which is located opposite to said filter paper with respect to the one of said layers, the one of said layers being a thermally fusible layer, said nonwoven fabric and said filter paper being joined together through the thermally fusible layer of the nonwoven fabric, said filter medium being arranged such that said nonwoven fabric and said filter paper are disposed upstream and downstream, respectively, in a direction in which said fluid to be filtered flows.
Claim 5
Dependent Claim
178 words
A filter which has a filter medium for an oil filter or an air filter for an internal combustion engine to remove dust particles from a fluid to be filtered; said filter medium comprising a nonwoven fabric of a lower fiber density which comprises at least two layers, and a filter paper of a higher fiber density, said nonwoven fabric and said filter paper being superposed in a laminated structure, one of said layers of the nonwoven fabric, which is closer to said filter paper, having a fiber density lower than that of the other of said layers of the nonwoven fabric which is located opposite to said filter paper with respect to the one of said layers, the one of said layers being a thermally fusible layer, said nonwoven fabric and said filter paper being joined together through the thermally fusible layer of the nonwoven fabric, said filter medium being arranged such that said nonwoven fabric and said filter paper are disposed upstream and downstream, respectively, in a direction in which said fluid to be filtered flows.
Claim 6
Dependent Claim
56 words
A filter according to claim 3, wherein the other of said layers has a fiber density of 0.15 to 0.25 g/cm 3 , while the one of said layers has a fiber density of 0.1 to 0.2 g/cm 3 and said filter paper has a relatively high fiber density of 0.2 to 0.3 g/cm 3 .
References Cited (Backward Citations)
US3003643A
Cited
US3452877A
Cited
US3591010A
Cited
US3690852A
Cited
US3815341A
Cited
US4073732A
Cited
US4093437A
Cited
US4111815A
Cited
US4257791A
Cited
US4528008A
Cited
US4564376A
Cited
US4522876A
Cited
US4619674A
Cited
US4707269A
Cited
US4668393A
Cited
US4793923A
Cited
US4759782A
Cited
US4687697A
Cited
US4925560A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-12-10 | 1994-06-11 | 1994-12-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-12-10 | 1998-06-11 | 1998-12-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-12-10 | 2002-06-11 | 2002-12-11 | $7700.00 | Window Closed / Lapsed |