Open flow filter with safety element

A filter comprising a pleated main filter element having a plurality of pleats in a closed loop having an outer perimeter defined by a plurality of outer pleat tips, and an inner perimeter defined by a plurality of inner pleat tips, said loop having a hollow interior extending along a given axis, wherein fluid to be filtered flows through said main filter element from an upstream dirty side to a downstream clean side, and flows axially in said hollow interior, said main filter element having an axial flow passage extending along said axis and circumscribing said hollow interior and having a flow perimeter greater than said inner perimeter, a safety filter element downstream of said main filter element and filtering both the axial flow in said hollow interior and additional flow between said flow perimeter and said inner perimeter, wherein said main filter element has first and second axial ends, said first axial end being open and providing said axial flow passage therethrough, said safety filter element includes a portion at said first axial end of said main filter element and outside of said hollow interior and axially aligned with the area between said flow perimeter and said inner perimeter, and wherein said safety filter element has first and second closed loop portions, said first closed loop portion of said safety filter element is in said hollow interior of said main filter element, said second closed loop portion of said safety filter element is exterior of said hollow interior of said main filter element and covers the area between said flow perimeter and said inner perimeter at said first axial end of said main filter element.

A filter comprising a pleated main filter element having a plurality of pleats in a closed loop having an outer perimeter defined by a plurality of outer pleat tips, and an inner perimeter defined by a plurality of inner pleat tips, said loop having a hollow interior extending along a given axis, wherein fluid to be filtered flows through said main filter element from an upstream dirty side to a downstream clean side, and flows axially in said hollow interior, said main filter element having an axial flow passage extending along said axis and circumscribing said hollow interior and having a flow perimeter greater than said inner perimeter, a safety filter element downstream of said main filter element and filtering both the axial flow in said hollow interior and additional flow between said flow perimeter and said inner perimeter, wherein said main filter element has first and second axial ends, said first axial end is open and provides an axial flow exit passage therethrough, said safety filter element is in said hollow interior downstream of said main filter element and has first and second axial ends, said first axial end of said safety filter element is adjacent said first axial end of said main filter element, said first axial end of said safety filter element is open and provides an axial flow exit passage therethrough, and comprising a first end cap at said first axial end of said main filter element, and a second end cap at said first axial end of said safety filter element, and wherein said filter is mounted in a housing having an axial end with a flange extending axially between said first and second end caps and sealed respectively thereagainst, said flange having an outer surface sealed against said first end cap, said flange having an inner surface sealed against said second end cap.

A filter comprising a pleated main filter element having a plurality of pleats in a closed loop having an outer perimeter defined by a plurality of outer pleat tips, and an inner perimeter defined by a plurality of inner pleat tips, said loop having a hollow interior extending along a given axis, wherein fluid to be filtered flows through said main filter element from an upstream dirty side to a downstream clean side, and flows axially in said hollow interior, said main filter element having first and second axial ends, said first axial end being open and providing an axial flow exit passage therethrough, a safety filter element in said hollow interior downstream of said main filter element and having first and second axial ends, said first axial end of said safety filter element being adjacent said first axial end of said main filter element, said first axial end of said safety filter element being open and providing an axial flow exit passage therethrough, said safety filter element being tapered along said axis from a wider radial width at said first axial end to a narrower radial width at said second axial end, to provide lateral clearance of said second axial end of said safety filter element within said hollow interior at said second axial end of said main filter element to facilitate lateral rocking back and forth of said second end of said main filter element to facilitate removal of the latter without removing said safety filter element during servicing.

A fluid filter comprising a housing extending axially along an axis, a pleated main filter element having a plurality of pleats in a closed loop having an outer perimeter defined by a plurality of outer pleat tips, and an inner perimeter defined by a plurality of inner pleat tips, said loop having a hollow interior extending along said axis, wherein fluid to be filtered flows through said main filter element from an upstream dirty side to a downstream clean side, said pleats forming wall segments extending in serpentine manner between said inner and outer pleat tips, said wall segments extending axially between upstream and downstream ends, said wall segments defining axial flow channels therebetween, said upstream ends of said wall segments being alternately sealed to each other to define a first set of flow channels open at their upstream ends, and a second set of flow channels interdigitated with said first set of flow channels and closed at said upstream ends, said downstream ends of said wall segments being alternately sealed to each other such that said first set of flow channels have closed downstream ends, and said second set of flow channels have open downstream ends, such that fluid flows substantially directly axially through said main filter element, through said open upstream ends of said first set of flow channels then through said wall segments then through said open downstream ends of said second set of flow channels, a safety filter element in said housing downstream of said main filter element, wherein said safety filter element is a closed loop member having at least a portion thereof axially aligned with said flow channels, and wherein said closed loop safety filter element has a hollow interior axially aligned with said hollow interior of said main filter element.

A fluid filter comprising a housing extending axially along an axis, a pleated main filter element having a plurality of pleats in a closed loop having an outer perimeter defined by a plurality of outer pleat tips, and an inner perimeter defined by a plurality of inner pleat tips, said loop having a hollow interior extending along said axis, wherein fluid to be filtered flows through said main filter element from an upstream dirty side to a downstream clean side, said pleats forming wall segments extending in serpentine manner between said inner and outer pleat tips, said wall segments extending axially between upstream and downstream ends, said wall segments defining axial flow channels therebetween, said upstream ends of said wall segments being alternately sealed to each other to define a first set of flow channels open at their upstream ends, and a second set of flow channels interdigitated with said first set of flow channels and closed at said upstream ends, said downstream ends of said wall segments being alternately sealed to each other such that said first set of flow channels have closed downstream ends, and said second set of flow channels have open downstream ends, such that fluid flows substantially directly axially through said main filter element, through said open upstream ends of said first set of flow channels then through said wall segments then through said open downstream ends of said second set of flow channels, a safety filter element in said housing downstream of said main filter element, wherein said second set of flow channels are interior flow channels facing inwardly toward said hollow interior and are open at said inner perimeter such that fluid additionally flows through said inner perimeter, and wherein said safety filter element has a first portion filtering fluid flow in said hollow interior crossing said inner perimeter, and a second portion filtering said flow through said open downstream ends of said second set of flow channels.

A fluid filter comprising a housing extending axially along an axis, a pleated main filter element having a plurality of pleats in a closed loop having an outer perimeter defined by a plurality of outer pleats, and an inner perimeter defined by a plurality of inner pleats, said loop having a hollow interior extending along said axis, wherein fluid to be filtered flows through said main filter element from an upstream dirty side to a downstream clean side, said pleats forming wall segments extending in serpentine manner between said inner and outer pleat tips, said wall segments extending axially between upstream and downstream ends, said wall segments defining axial flow channels therebetween, said upstream ends of said wall segments being alternately sealed to each other to define a first set of flow channels open at their upstream ends, and a second set of flow channels interdigitated with said first set of flow channels and closed at said upstream ends, said downstream ends of said wall segments being alternately sealed to each other such that said first set of flow channels have closed downstream ends, and said second set of flow channels have open downstream ends, such that fluid flows substantially directly axially through said main filter element, through said open upstream ends of said first set of flow channels then through said wall segments then through said open downstream ends of said second set of flow channels, a safety filter element in said housing downstream of said main filter element, wherein said main filter element has first and second axial ends, said first axial end is open and provides an axial flow exit passage therethrough, said safety filter element is in said hollow interior downstream of said main filter element and has first and second axial ends, said first axial end of said safety filter element is adjacent said first axial end of said main filter element, said first axial end of said safety filter element is open and provides an axial flow exit passage therethrough, and comprising a first end cap at said first axial end of said main filter element, and a second end cap at said first axial end of said safety filter element, and wherein said filter is mounted in a housing having an axial end with a flange extending axially between said first and second end caps and sealed respectively thereagainst, said flange having an outer surface sealed against said first end cap, said flange having an inner surface sealed against said second end cap.