Filter with tri-flow path combinations

1. A filter comprising:

a housing extending axially along an axial direction and directing fluid along an axial flow path therethrough from upstream to downstream,

a plurality of annular filter elements in said housing, the axis of the annulus of each annular filter element extending axially along said axial direction, said annular filter elements being arranged in axially staggered relation in said housing, said plurality of annular filter elements comprising at least a first annular filter element, and a second annular filter element axially downstream of said first annular filter element,

said housing having a plurality of flow path segments comprising a first flow path segment flowing axially through said first annular filter element and filtered thereby, a second flow path segment flowing axially along a path laterally adjacent first annular filter element and unfiltered thereby, said second flow path segment being laterally adjacent said first flow path segment, a third flow path segment flowing axially through said second annular filter element and filtered thereby, a fourth flow path segment flowing axially along a path laterally adjacent said second annular filter element and unfiltered thereby, said fourth flow path segment being laterally adjacent said third flow path segment, said third and fourth flow path segments being axially downstream of said first and second flow path segments, said first flow path segment flowing serially into said fourth flow path segment, said second flow path segment flowing serially into said third flow path segment, and

an outer annular filter element concentrically surrounding said first and second annular filter elements and providing additional filtration capacity in addition to said first and second annular filter elements.

2. The filter according to claim 1 wherein said outer annular filter element receives fluid flow laterally thereinto.

3. A filter for a housing extending axially along an axial direction and directing fluid along an axial flow path therethrough from upstream to downstream, the filter comprising:

a plurality of annular filter elements for positioning in said housing, the axis of the annulus of each annular filter element extending axially along said axial direction, said annular filter elements being arranged in axially staggered relation in said housing, said plurality of annular filter elements comprising at least a first annular filter element, and a second annular filter element axially downstream of said first annular filter element, and

an outer filter element surrounding the plurality of annular filter elements,

said housing having a plurality of flow path segments comprising a first flow path segment flowing axially through said first annular filter element and filtered thereby, a second flow path segment flowing axially along a path laterally adjacent first annular filter element and unfiltered thereby, said second flow path segment being laterally adjacent said first flow path segment, a third flow path segment flowing axially through said second annular filter element and filtered thereby, a fourth flow path segment flowing axially along a path laterally adjacent said second annular filter element and unfiltered thereby, said fourth flow path segment being laterally adjacent said third flow path segment, said third and fourth flow path segments being axially downstream of said first and second flow path segments, said first flow path segment flowing serially into said fourth flow path segment, said second flow path segment flowing serially into said third flow path segment,

wherein at least one of the following conditions is satisfied:

a) said first flow path segment concentrically surrounds said second flow path segment;

b) said fourth flow path segment concentrically surrounds said third flow path segment.

4. The filter according to claim 3 wherein said first flow path segment concentrically surrounds said second flow path segment.

5. The filter according to claim 3 wherein said fourth flow path segment concentrically surrounds said third flow path segment.

6. The filter according to claim 3 wherein in combination said first flow path segment concentrically surrounds said second flow path segment, and said fourth flow path segment concentrically surrounds said third flow path segment.

7. A method for filtering fluid including passing the fluid through a filter in a housing extending axially along an axial direction, the method comprising:

directing fluid along an axial flow path from upstream to downstream,

providing a plurality of annular filter elements for positioning in said housing, the axis of the annulus of each annular filter element extending axially along the axial direction, arranging said annular filter elements in axially staggered relation in said housing, the plurality of annular filter elements including a first annular filter element a second annular filter element axially downstream of said first annular filter element,

providing an outer filter element surrounding the plurality of annular filter elements,

providing a plurality of flow path segments including a first flow path segment flowing axially through said first annular filter element and filtered thereby, a second flow path segment flowing axially along a path laterally adjacent said first annular filter element and unfiltered thereby, said second flow path segment being laterally adjacent said first flow path segment, a third flow path segment flowing axially through said second annular filter element and filtered thereby, and a fourth flow path segment flowing axially along a path laterally adjacent said second annular filter element and unfiltered thereby, said fourth flow path segment being laterally adjacent said third flow path segment, providing said third and fourth flow path segments axially downstream of said first and second flow path segments,

flowing said first flow path segment serially into said fourth flow path segment,

flowing said second flow path segment serially into said third flow path segment,

arranging said flow path segments to satisfy at least one of the following conditions:

a) concentrically surrounding said second flow path segment with said first flow path segment; and

b) concentrically surrounding said third flow path segment with said fourth flow path segment.

8. The method according to claim 7 comprising concentrically surrounding said second flow path segment with said first flow path segment.

9. The method according to claim 7 comprising concentrically surrounding said third flow path segment with said fourth flow path segment.

10. The method according to claim 7 comprising in combination concentrically surrounding said second flow path segment with said first flow path segment, and concentrically surrounding said third flow path segment with said fourth flow path segment.