| 摘要 |
A filter assembly including a frame having a through passageway between front and rear surfaces surrounded by a perimeter portion; and a filter element including a sheet of flexible filter media with longitudinal attachment strips at opposite ends and extending at about a right angle to opposite edges of the sheet. Structure on the frame receives and positions the filter element with the sheet of filter media extending across the passageway with an inlet surface of the sheet facing the same direction as the front surface of the frame and with the attachment strips of the filter element extending along opposite end parts of the perimeter portion. The structure includes first and second generally parallel spaced linear abutments extending along the perimeter portion between its end parts and laying along the opposite edges of the sheet of filter material, and spaced first and second projections on each of the end parts of said frame engaged in first and second openings on a different one of the attachment strips. The first projection at the first end part is spaced the same first distance from the first linear abutment as the first projection at the second end part is spaced from the second linear abutment, and the second projection at said first end part is spaced the same second distance from the second linear abutment as the second projection at the second end is spaced from the first linear abutment. Those first and second distances are different so that the filter element can be mounted on the frame with either of the attachment strips engaged with the projections at either of the end parts while the filter element can only be mounted on the frame with the inlet surface of the sheet facing the same direction as the front surface of the frame. |
