| 摘要 |
A filter element (202, 250) includes pleated filter media (26) having a plurality of pleats (28) in a closed annular loop having an outer perimeter (30) defined by a plurality of outer pleat tips (32), an inner perimeter (34) defined by a plurality of inner pleat tips (36), the loop having a hollow interior (38) extending along an axis (40), wherein fluid to be filtered flows laterally through the filter media and flows axially in the hollow interior (38). The filter element has an axial flow passage (56a) along the axis (40) and circumscribing the hollow interior (38) and has a flow perimeter (218) greater than the inner perimeter (34) of the filter element defined by the inner pleat tips (36), and in the preferred embodiment substantially the same as the outer perimeter (30) defined by the outer pleat tips (32), to provide axial flow (58) through the hollow interior (38) and additional axial flow (59 and 59a) through the axial ends (68) of the pleats.
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