Filter element with zig-zag pleats

Claim 2

A filter element including a generally ring-like structure including a plurality of generally radial sections each converging generally radially inwardly and having a plurality of generally circumferential zigzag pleats of a filtering sheet material, said radial sections being circumferentially arranged such that the radially inner ends of said radial sections cooperate to define a central space disposed substantially centrally of said ring-like structure and generally radial spaces are defined between said radial sections, the zigzag pleats of each radial section having circumferential dimensions which are substantially gradually decreased radially inwardly of said ring-like structure, some of said radial spaces being radially inwardly open to said central space and being closed at the radially outer ends by said filtering sheet material, the other radial spaces being closed at the radially inner ends by said filtering sheet material, said radially inwardly open radial spaces and the other radial spaces being circumferentially alternately arranged, and said radially inwardly open radial spaces being closed at the axially opposite ends by end walls.

Claim 3

A filter element according to claim 1, wherein said the other radial spaces are radially outwardly open to the outside of said ring-like structure.

Claim 4

A filter element according to claim 1, wherein said end walls are fluid permeable.

Claim 5

A filter element according to claim 3, wherein each end wall is formed of a layer of a foamed plastic material.

Claim 6

A filter element according to claim 3, wherein the end walls of at least one of said radially inwardly open radial spaces have a fluid permeability different from the fluid permeability of the end walls of the other radially inwardly open radial spaces.

Claim 7

A filter element according to claim 1, wherein said ring-like structure further includes at least one additional radial section formed by a filtering material having a fluid-permeability different from those of the other radial sections.

Claim 8

A filter element according to claim 6, wherein said additional radial section is formed of another filtering sheet material and has a plurality of generally circumferentially zigzag pleats.

Claim 9

A filter element according to claim 6, wherein said additional radial section is formed of another filtering sheet material and has a plurality of generally radially zigzag pleats.

Claim 10

A filter element according to claim 1, wherein each of said radially inwardly open radial spaces is closed at the radially outer end by a generally circumferentially extending and generally arcuate section formed of said filtering sheet material and having a plurality of generally radial zigzag pleats, the arcuate sections being circumferentially arranged with their circumferential ends disposed in cricumferentially spaced relationship to each other so that the arcuate sections from a circumferentially discontinuous ring of radial pleats outside the circumferentially zigzag pleats.

Claim 11

A filter element according to claim 1 wherein the respective circumferential ends of the zigzag pleats of each circumferentially adjacent pair of radial sections are located close to each other and disposed in circumferentially adjacent relationship.

Claim 12

A filter element including a generally ring-like structure including a plurality of generally radial sections each having a plurality of generally circumferential zigzag pleats of a filtering sheet material, each of at least some said radial sections converging generally radially inwardly, all of said radial sections being circumferentially arranged such that the radially inner ends of said radial sections cooperate to define a central space disposed substantially centrally of said ring-like structure and generally radial spaces are defined between said radial sections, some of said radial spaces being radially inwardly open to said central space and being closed at the radially outer ends by said filtering sheet material, the other radial spaces being closed at the radially inner ends by said filtering sheet material, said radially inwardly open radial spaces and the other radial spaces being circumferentially alternately arranged, the axially opposite ends of said ring-like structure being provided with end walls in which radial slits are formed in communication with said the other radial spaces and said the other radial spaces having radially outer ends in the form of substantially axial slits open in the outer periphery of said ring-like structure, said raial and axial slits forming passages for a fluid to be filtered.

Claim 13

A filter element including a generally ring-like structure including a plurality of generally radial sections each having a plurality of generally circumferential zigzag pleats of a filtering sheet material, each of at least some said radial sections converging generally radially inwardly, all of said radial sections being circumferentially arranged such that the radially inner ends of said radial sections cooperate to define a central space disposed substantially centrally of said ring-like structure and generally radial spaces are defined between said radial sections, some of said radial spaces being radially inwardly open to said central space and being closed at the radially outer ends by said filtering sheet material, the other radial spaces being closed at the radially inner ends by said filtering sheet material, said radially inwardly open radial spaces and the other radial spaces being circumferentially alternately arranged, the axially opposite ends of said ring-like structure being provided with end walls in which radial slits are formed in communication with said the other radial spaces and said the other radial spaces having radially outer ends in the form of substantially axial slits open in the outer periphery of said ring-like structure, said raial and axial slits forming passages for a fluid to be filtered.

Claim 14

A filter element including a generally ring-like structure including a plurality of generally radial sections each converging generally radially inwardly and having a plurality of generally circumferential zigzag pleats of a filtering sheet material, said radial sections being circumferentially arranged such that the radially inner ends of said radial sections cooperate to define a central space disposed substantially centrally of said ring-like structure and generally radial spaces are defined between said radial sections the zigzag pleats of each radial section having circumferential dimensions which are substantially gradually decreased radially inwardly of said ring-like structure, some of said radial spaces being radially inwardly open to said central space and being closed at the radially outer ends by said filtering sheet material, the other radially spaces being closed at the radially inner ends by said filtering sheet material, said radially inwardly open radial spaces and the other radial spaces being circumferentially alternately arranged, and said radially inwardly open radial spaces being closed at the axially opposite ends by end walls, said ring-like structure further including at least one additional radial section formed of a block of a fluid-permeable material having a fluid-permeability different from those of the other radial sections.

Claim 15

A filter element including a generally ring-like structure including a plurality of generally radial sections each converging generally radially inwardly and having a plurality of generally circumferential zigzag pleats of a filtering sheet material, said radial sections being circumferentially arranged such that the radially inner ends of said radial sections cooperate to define a central space disposed substantially centrally of said ring-like structure and generally radial spaces are defined between said radial sections the zigzag pleats of each radial section having circumferential dimensions which are substantially gradually decreased radially inwardly of said ring-like structure, some of said radial spaces being radially inwardly open to said central space and being closed at the radially outer ends by said filtering sheet material, the other radially spaces being closed at the radially inner ends by said filtering sheet material, said radially inwardly open radial spaces and the other radial spaces being circumferentially alternately arranged, and said radially inwardly open radial spaces being closed at the axially opposite ends by end walls, said ring-like structure further including at least one additional radial section formed of a block of a fluid-permeable material having a fluid-permeability different from those of the other radial sections.

Claim 16

A filter element according to claim 12, wherein said end wall is fluid-permeable.

Claim 17

A filter element according to claim 13, wherein said end wall is formed of a layer of a foamed plastic material.

Claim 18

A filter element according to claim 13, wherein the end wall of at least one of said radially inwardly open radial spaces has a fluid-permeability different from the fluid permeability of the end walls of the other radially inwardly open radial spaces.

Claim 19

A filter element according to claim 12, wherein said the other radial spaces are radially outwardly open to the outside of said ring-like structure.

Claim 20

A filter element according to claim 12, wherein said additional radial section is formed of another filtering sheet material and has a plurality of generally circumferentially zigzag pleats.

Claim 21

A filter element according to claim 12, wherein said additional radial section is formed of another filtering sheet material and has a plurality of generally radially zigzag pleats.

Claim 22

A filter element according to claim 12, wherein each of said radially inwardly open radial spaces is closed at the radially outer end by a generally circumferentially extending and generally arcuate section formed of said filtering sheet material and having a plurality of generally radial zigzag pleats, the arcuate sections being circumferentially arranged with their circumferential ends disposed in circumferentially spaced relationship to each other so that the arcuate sections form a circumferentially discontinuous ring of radial pleats outside the circumferentially zigzag pleats.