Filter device with micropleats and macropleats

• US 5,098,767 A
• Filed: 03/18/1991
• Issued: 03/24/1992
• Est. Priority Date: 02/15/1989
• Status: Expired due to Fees

• Current Assignee: Pall Corporation (Danaher Corporation)
• Original Assignee: Pall Corporation (Danaher Corporation)
• Inventors: Linnersten, Staffan B.
• Primary Examiner(s): Robinson, Ellis P.
• Assistant Examiner(s): Watkins, III, William P.
• Application Number:
  US07/670,522
• Time in Patent Office: 372 Days
• Field of Search: 428/181, 428/182, 428/184, 428/213, 428/215, 428/220, 428/228, 428/251, 428/252, 428/288, 428/296, 428/311.5, 428/343, 428/349, 428/435, 428/477.7, 210/493.5, 55/97, 55/497, 55/499, 55/500, 55/501, 55/521
• US Class Current: 95/273
• CPC Class Codes: B01D 2265/04 Permanent measures for connecting different parts of the filter, e.g. welding, glueing or moulding
• CPC Class Codes: B01D 46/10 Particle separators, e.g. dust precipitators, using filter plates, sheets or pads having plane surfaces
• CPC Class Codes: B01D 46/121 V-type arrangements
• CPC Class Codes: B01D 46/521 using folded, pleated material
• CPC Class Codes: Y10T 428/24686 Pleats or otherwise parallel adjacent folds
• CPC Class Codes: Y10T 428/24694 Parallel corrugations
• CPC Class Codes: Y10T 428/24711 Plural corrugated components
• CPC Class Codes: Y10T 428/2495 Thickness [relative or absolute]
• CPC Class Codes: Y10T 428/24967 Absolute thicknesses specified
• CPC Class Codes: Y10T 428/28 Web or sheet containing structurally defined element or component and having an adhesive outermost layer
• CPC Class Codes: Y10T 428/2826 Synthetic resin or polymer
• CPC Class Codes: Y10T 428/31623 Next to polyamide or polyimide
• CPC Class Codes: Y10T 428/31765 Inorganic-containing or next to inorganic-containing

Abstract

A high efficiency air filter is described which comprises a depth filter sheet that has been formed with micropleats stabilized by application of a strip of a thermoplastic adhesive across the peaks of the micropleats and then formed into a macropleated structure with the axes of the micropleats and the macropleats being essentially parallel. The micropleats preferably have a bending radius of less than about 0.01 inch.

Claims

1. A filter assembly comprising a frame defining a flow path from inlet to outlet side and a filter disposed within said frame across the flow path, said filter being formed from a sheet of filter material having a thickness no greater than about 0.03 inch and formed into micropleats, and having at least one strip of adhesive material applied across the peaks of the micropleats and oriented at right angles to the axes of the micropleats, a said micropleated sheet defining macropleats with pleat axes generally parallel to those of the micropleats.

2. A filter assembly according to claim 1 in which at least one strip of adhesive material is applied to the peaks of the micropleats on both faces of the micropleated sheet.

3. A filter assembly according to claim 2 in which the adhesive material is a thermoplastic polymer.

4. A filter assembly according to claim 1 in which the sheet has a thickness of less than about 0.02 inch.

5. A filter assembly according to claim 4 in which the sheet is supported on a porous web material.

6. A filter assembly according to claim 5 in which the porous web is formed of a spun-bonded, continuous filament nylon.

7. A filter assembly according to claim 1 in which the sheet is formed from resin-impregnated glass fibers.

8. A filter assembly according to claim 1 in which the depth of the macropleats is at least eight times the depth of the micropleats.

23. A method of filtering airplane cabin air which comprises passing the air through a filter according to claim 1.

9. A filter assembly comprising a frame defining a flow path from inlet to outlet side and, disposed, within said frame, a filter across the flow path, said filter comprising a sheet having a thickness no greater than about 0.03 inch and formed into micropleats having a bending radius of less than the critical radius and a micropleat depth to sheet thickness ratio of about from 10 to 100, said micropleated sheet defining macropleats with the axes of said macropleats substantially parallel to those of the micropleats.

10. A filter assembly according to claim 9 in which the sheet has a thickness of less than 0.02 inch.

11. A filter assembly according to claim 10 in which the depth filter sheet is supported on a porous web material.

12. A filter assembly according to claim 11 in which the porous web is formed of a spun-bonded, continuous filament nylon.

13. A filter assembly according to claim 9 in which the sheet is formed from resin-impregnated glass fibers.

14. A filter assembly according to claim 9 in which the depth of the macropleats is at least eight times the depth of the micropleats.

24. A method of filtering airplane cabin air which comprises passing the air through a filter according to claim 9.

15. A filter assembly comprising a frame defining a flow path from inlet to outlet sides and disposed within said frame a filter across the flow path, said filter comprising a micropleated sheet formed of spun-bonded glass fibers supported on a porous web of spun-bonded nylon, said sheet having a thickness of from about 0.01 to 0.02 inch, and from 12 to 15 micropleats to the linear inch formed therein, said micropleats having a bending radius of less than about 0.01 inch and a ratio of the depth of the micropleats to the sheet thickness of from 20 to 30, said micropleated sheet defining macropleats with pleat axes generally parallel to the axes of the micropleats.

18. An air filter assembly according to claim 15 wherein at least one strip of adhesive material is applied across the peaks of the micropleats and oriented generally perpendicular to the axes of the micropleats.

19. An air filter assembly according to claim 18 wherein the adhesive material is a thermoplastic polymer and the strips are applied on both faces of the micropleated sheet.

25. A method of filtering airplane cabin air which comprises passing the air through a filter according to claim 15.

27. A method of filtering airplane cabin air which comprises passing the air through an air filter according to claim 18.

16. An air filter assembly comprising a frame defining a flow path from inlet to outlet sides and a filter disposed within said frame across the flow path, said filter comprising a sheet having a thickness no greater than about 0.03 inch and from 12 to 15 micropleats per linear inch, each micropleat having a bending radius of less than about 0.01 inch and a micropleat depth to sheet thickness ratio of from about 20 to 30, said micropleated sheet defining macropleats with pleat axes generally parallel to the axes of the micropleats.

17. An air filter assembly according to claim 16 having inlet and outlet sides wherein the distance between adjacent peaks of the macropleated sheets on the inlet side is from 0.5 to 2.0 times the corresponding spacing on the outlet side.

20. An air filter assembly according to claim 16 wherein said sheet has a thickness of less than about 0.02 inch and is supported on a porous web.

26. A method of filtering airplane cabin air which comprises passing the air through a filter according to claim 16.

21. An air filter assembly comprising a frame having a generally regular box shaped configuration with one dimension shorter than the other two, said shorter dimension being the direction of air flow through the filter assembly and, disposed within said frame, a composite sheet of a glass fiber filter with a thickness of less than about 0.02 inch supported upon a porous web of continuous nylon filaments, said composite sheet having from 12 to 15 micropleats per linear inch with the bending radius of the micropleats being less than 0.01 inch and the ratio of the depth of the micropleats to the sheet thickness being from about 20 to 30, and said micropleated sheet defining a macropleated structure with the axes of the macropleats being generally parallel to the axes of the micropleats.

22. An air filter assembly according to claim 21 having inlet and outlet sides in which the distance between adjacent peaks of the macropleats on the inlet side is from 0.5 to 2.0 times the corresponding opening on the outlet side.

28. A method of filtering airplane cabin air which comprises passing the air through an air filter according to claim 21.

29. A method of filtering airplane cabin air which comprises passing the air through an air filter according to claim 22.

30. A filter assembly for removing particulate matter from a gas, the filter assembly comprising a frame including an inlet, an outlet, and an impervious side wall defining a gas flow path between the inlet and the outlet;

a filter means disposed across the gas flow path within the frame and including edges sealed against the side wall of the frame, the filter being formed into micropleats having peaks and axes, the axes extending generally parallel to the peaks, and further formed into macropleats having V-shaped configurations and axes generally parallel to the axes of the micropleats; and

a plurality of strips of adhesive material extending across the peaks of the micropleats and generally oriented at right angles to the axes of the micropleats.

31. A filter assembly comprising a frame defining a flow path from inlet to outlet side, and a filter disposed within said frame across the flow path, said filter comprising a sheet having micropleats, and the micropleated sheet defining macropleats, wherein the bending radius of said micropleats is less than the critical radius.

32. The filter assembly according to claim 31 wherein said micropleats have at least one strip of adhesive material applied across the peaks of said micropleats.

33. The filter assembly according to claim 31 wherein said macropleats have pleat axes generally parallel to those of said micropleats.

34. The filter assembly according to claim 31 wherein the critical radius is between about 0.01 inch and about 0.015 inch.

35. A filter assembly comprising a frame defining a flow path from inlet to outlet side and a filter disposed within said frame across the flow path, said filter being formed from a sheet of filter material and formed into micropleats, and having at least one strip of adhesive material applied across the peaks of the micropleats, said micropleated sheet defining macropleats.