Pleated filter and method and apparatus for fabricating same

Claim 2

A filter for physically separating constituent components of a fluid, said filter comprising: a sheet-like member having a plurality of adjacent layers, each layer being porous to at least one constituent component of said fluid, at least one of said layers being generally impervious to a second constituent component of said fluid, said sheet-like member being in the form of a hollow peripherally integral and continuous tube having a longitudinal tube axis and a multiplicity of successively adjacent pleats having fold edges oriented generally transversely of said longitudinal tube axis; said sheet-like member being a substantially solid, dimensionally stable body; said at least one of said layers which is generally impervious to said second constituent having a thickness; each of said pleats having a length; each pair of adjacent pleats being separated by a distance by material from ones of said layers which are adjacent to said at least one of said layers which is generally impervious to said second constituent; a ratio of said length to said distance being at least 10:1.

Claim 3

The filter according to claim 1 wherein said plurality of adjacent layers comprises two outer layers and an inner layer disposed between said two outer layers, wherein said inner layer corresponds to said at least one of said layers and is impervious to said second component of said fluid.

Claim 4

The filter according to claim 2 wherein said two outer layers each comprise a respective continuous filamentary tow of substantially continuous thermpolastic fibers.

Claim 5

The filter according to claim 2 wherein said tube has a longitudinally-extending cylindrical configuration with an annular transverse cross-section.

Claim 6

The filter according to claim 2 wherein said tube has a longitudinally-extending configuration with a polygonal transverse cross-section.

Claim 7

The filter according to claim 2 wherein said inner layer and said outer layers are respective sheets of the same material.

Claim 8

The filter according to claim 2 wherein said outer layers are a nylon and said inner layer is a different material having a lower porosity than said nylon.

Claim 9

The filter according to claim 1 wherein each of said layers has a different porosity.

Claim 10

The filter according to claim 1 wherein said tube has a longitudinally-extending cylindrical configuration with an annular transverse cross-section.

Claim 11

The filter according to claim 1 wherein said tube has a longitudinally-extending configuration with a polygonal transverse cross-section.

Claim 12

A filter as claimed in claim 1, wherein said ratio is at least 100:1.

Claim 13

A filter as claimed in claim 1, wherein said tube has a wall thickness of approximately one inch, a circumference of approximately 10 inches, and said ratio is approximately 100; said tube having a filter surface area of approximately 500 square inches per linear inch.

Claim 16

The method according to claim 13 wherein the step of flowing includes flowing said conveying gas into said passage from a plurality of angularly spaced apertures disposed about the transverse periphery of the passage at said conveyor location.

Claim 17

The method according to claim 14, wherein the step of flowing includes delivering the conveying gas into said passage at an angle in the range of 0° to 20° relative to longitudinal.

Claim 18

The method according to claim 13 wherein the step of folding includes the step of withdrawing the sheet-like member from an exit of said passage at an average linear speed which is lower than the linear speed at which said layers are fed to said entrance so as to cause said sheet-like member to be multiply crimped in said passage.

Claim 19

The method according to claim 16 wherein the step of folding further includes the step of: venting said conveying gas from said passage at a passage venting location having a widened transversed cross-section and which is longitudinally downstream of the conveyor location.

Claim 20

The method according to claim 17 further including the step of: introducing a heated gas into said passage and into direct contact with said sheet-like member at a heating location in said passage disposed downstream of said venting location.

Claim 21

The method according to claim 18 wherein the step of introducing heated gas includes flowing the heated gas against both sides of said sheet-like member.

Claim 22

The method according to claim 18 further including the step of delivering cooling gas into direct contact with the sheet-like member at a cooling location in said passage which is downstream of said heating location.

Claim 23

The method according to claim 20 wherein said cooling gas is pressurized air, said conveying gas is pressurized air, and said heating gas is pressurized steam.

Claim 24

The method according to claim 16 further including the step of: introducing heated gas into said passage and into direct contact with said sheet-like member at a passage heating location disposed downstream of said conveyor location.

Claim 25

The method according to claim 22 wherein the step of introducing heated gas includes flowing the heated gas against both sides of said sheet-like member.

Claim 26

The method according to claim 22 further including the step of delivering cooling gas into direct contact with the sheet-like member at a cooling location in said passage which is downstream of said heating location.

Claim 27

The method according to claim 13 wherein the predetermined transverse cross-section of said passage is an annulus having radially inner and outer walls.

Claim 28

The method according to claim 25 wherein said inner and outer walls are generally circular.

Claim 29

The method according to claim 25 wherein said inner and outer walls are polygonal.

Claim 30

The method according to claim 13 further comprising the step of pre-crimping at least one of said layers before feeding that layer into said passage.

Claim 31

The method according to claim 13 wherein the step of forming comprises the step of extruding a layer of fine fibers of a first material between two layers of a second material perform three layers of said sheet-like member.

Claim 34

The method according to claim 30 wherein the step of folding further includes the step of: venting said conveying gas from said passage at a passage venting location having a widened transverse cross-section and which is located longitudinally downstream of the conveyor location.

Claim 35

The method according to claim 31 further including the steps of: introducing a heated gas into said passage and into direct contact with said sheet-like member at a heating location in said passage disposed downstream of said venting location; and delivering cooling gas into direct contact with the sheet-like member at a cooling location in said passage which is downstream of said heating location.

Claim 38

The method according to claim 33 wherein the step of conveying includes flowing a conveyor gas into said passage at a conveyor location with a flow component directed longitudinally downstream of said passage.

Claim 39

The method according to claim 34 wherein the step of folding further includes the step of: venting said conveying gas from said passage at a passage venting location having a widened transversed cross-section and which is longitudinally downstream of the conveyor location.

Claim 40

The method according to claim 35 further including the step of: introducing a heated gas into said passage and into direct contact with said sheet-like member at a heating location in said passage disposed downstream of said venting location.

Claim 41

The method according to claim 36 further including the step of delivering cooling gas into direct contact with the sheet-like member at a cooling location in said passage which is downstream of said heating location.

Claim 42

The method according to claim 33 further including the step of: introducing heated gas into said passage and into direct contact with said sheet-like member at a passage heating location disposed downstream of said conveyor location.

Claim 43

The method according to claim 38 further including the step of delivering cooling gas into direct contact with the sheet-like member at a cooling location in said passage which is downstream of said heating location.

Claim 44

Apparatus for fabricating a multi-layer filter comprising: a longitudinally-extending passage of predetermined cross-sectional configuration, said passage having an entrance and an exit; a delivery means for delivering a sheet-like member having plural layers into said passage via said entrance at a predetermined speed, with said plural layers disposed in successively adjacent relation to one another, said plural layers being disposed transversely of the longitudinal direction of said passage; a conveyor means for translating said sheet-like member longitudinally through said passage; a forming means in said passage for forming said sheet-like member into an elongated hollow tube member having an continuous transverse periphery; said forming means including a pleating means for pleating said sheet-like member while it is conveyed from said passage to form multiple successively adjacent transverse pleats in said sheet-like member, such that each pleat includes said plural layers and a fold line oriented transversely to the longitudinal direction of said passage; and a means for withdrawing said tube member from said passage at a speed lower than said predetermined speed.

Claim 45

Apparatus for fabricating a multi-layer filter comprising: a longitudinally-extending passage of predetermined cross-sectional configuration, said passage having an entrance and an exit; a delivery means for delivering a sheet-like member having plural layers into said passage via said entrance at a predetermined speed, with said plural layers disposed in successively adjacent relation to one another, said plural layers being disposed transversely of the longitudinal direction of said passage; a conveyor means for translating said sheet-like member longitudinally through said passage; a forming means in said passage for forming said sheet-like member into an elongated hollow tube member having an continuous transverse periphery; said forming means including a pleating means for pleating said sheet-like member while it is conveyed from said passage to form multiple successively adjacent transverse pleats in said sheet-like member, such that each pleat includes said plural layers and a fold line oriented transversely to the longitudinal direction of said passage; and a means for withdrawing said tube member from said passage at a speed lower than said predetermined speed.

Claim 46

The apparatus according to claim 40 wherein said conveyor means comprises means for flowing a conveyor gas through said passage from a conveyor location in a downstream longitudinal direction to carry said sheet-like member through said passage.

Claim 47

The apparatus according to claim 41 wherein said pleating means includes a venting location located downstream of said conveyor location and wherein the cross-section of said passage is enlarged, said venting location including a plurality of vent openings for venting said conveyor gas from said passage.

Claim 48

The apparatus according to claim 42 further comprising means for introducing a heated gas into said passage at a heating location disposed downstream of said venting location, said means for introducing comprising a plurality of nozzles arranged to issue said heated gas into direct contact with said sheet-like member.

Claim 49

The apparatus according to claim 43 further comprising means for introducing a cooling gas into direct contact with said sheet-like member in said passage at a cooling location located downstream of said heating location.