Filter apparatus for a surface cleaning apparatus
A surface cleaning apparatus having an air flow path from a dirty air inlet to a clean air outlet and including an air treatment member, a suction motor and a filter assembly in the air flow path. The filter assembly includes at least two spaced apart physical filter elements with the upstream face of the second filter facing the downstream face of the first filter element. The filter assembly is configured to prevent air from bypassing the first physical filter media. The filter assembly includes a gap between the first filter element and the second filter element that acts as a header and reduces the flow rate of air incident on the second filter element.
1. A surface cleaning apparatus having an air flow path from a dirty air inlet to a clean air outlet and including an air treatment member, a suction motor and a filter assembly provided in the air flow path, the filter assembly comprising:
a) a first longitudinally extending annular physical filter media having an upstream face and a downstream face;
b) a second longitudinally extending annular physical filter media having an upstream face and a downstream face, wherein the upstream face of the second annular physical filter media is positioned interior the first annular physical filter media whereby the upstream face of the second annular physical filter media faces the downstream face of the first annular physical filter media, wherein the first and second longitudinally extending annular physical filter media are discrete elements that are separable from each other; and,
c) a longitudinally extending gap located between the upstream face of the second annular physical filter media and the downstream face of the first annular physical filter media, the gap having first and second longitudinally spaced apart ends wherein the first and second longitudinally spaced apart ends are closed whereby prior to passing through the second longitudinally extending annular physical filter media, air travels through the first longitudinally extending annular physical filter media,
wherein the first longitudinally extending annular physical filter media is maintained in position with respect to the second longitudinally extending annular physical filter media by a compressive force applied by the first longitudinally extending annular physical filter media when the first longitudinally extending annular physical filter media is positioned overlying the second longitudinally extending annular physical filter media.
2. The surface cleaning apparatus of claim 1 wherein the filter assembly is a pre-motor filter.
3. The surface cleaning apparatus of claim 1 wherein the filter assembly is removable from the surface cleaning apparatus as a unit.
4. The surface cleaning apparatus of claim 1 wherein the first annular physical filter media is mounted in a filter housing and the filter housing has an absence of a by-pass passage.
5. The surface cleaning apparatus of claim 4 further comprising an upstream first filter header and the filter housing and the first filter header direct all air flowing through the air flow path at a location immediately upstream of the first filter header through the first annular physical filter media.
6. The surface cleaning apparatus of claim 1 wherein the first annular physical filter media provides the only air passage from a location immediately upstream of the first annular physical filter media to a location downstream of the first annular physical filter media.
7. The surface cleaning apparatus of claim 1 wherein each of the first and second annular physical filter media have an average pore size and the average pore size of the second annular physical filter media is smaller than the average pore size of the first annular physical filter media.
8. The surface cleaning apparatus of claim 7 wherein the first annular physical filter media comprises foam and the second annular physical filter media is selected from the group consisting of felt, electret and foam.
9. The surface cleaning apparatus of claim 1 wherein each of the first and second annular physical filter media has a diameter and the diameter of the first annular physical filter media is up to 25% larger than the diameter of the second annular physical filter media.
10. The surface cleaning apparatus of claim 1 wherein each of the first and second annular physical filter media has a cross-sectional area in a direction transverse to air flow therethrough and the cross-sectional area of the first annular physical filter media is up to 25% larger than the cross-sectional area of the second annular physical filter media.
11. The surface cleaning apparatus of claim 1 further comprising a third annular physical filter media having an upstream face and a downstream face,
wherein the upstream face of the third annular physical filter media is positioned interior the second annular physical filter media whereby the upstream face of the third annular physical filter media faces the downstream face of the second annular physical filter media.
12. The surface cleaning apparatus of claim 11 wherein the third annular physical filter media has an average pore size and the average pore size of the third annular physical filter media is smaller than the average pore size of the second annular physical filter media.
13. The surface cleaning apparatus of claim 12 wherein each of the first and second annular physical filter media comprises foam and the third annular physical filter media is selected from the group consisting of felt, electret and foam.
14. The surface cleaning apparatus of claim 12 wherein the first annular physical filter media comprises foam and the second annular physical filter media is selected from the group consisting of felt, electret and foam.
15. The surface cleaning apparatus of claim 11 wherein each of the first, second and third annular physical filter media has a diameter and the diameter of the first annular physical filter media is up to 25% larger than the diameter of the second annular physical filter media, and the diameter of the third annular physical filter media is up to 25% larger than of the diameter of the second annular physical filter media.
16. The surface cleaning apparatus of claim 11 wherein each of the first, second and third annular physical filter media has a cross-sectional area in a direction transverse to air flow therethrough and the cross-sectional area of the first annular physical filter media is up to 25% larger than the cross-sectional area of the second annular physical filter media, and the cross-sectional area of the third annular physical filter media is up to 25% larger than the cross-sectional area of the second annular physical filter media.
17. A surface cleaning apparatus having an air flow path from a dirty air inlet to a clean air outlet and including an air treatment member, a suction motor and a filter assembly provided in the air flow path, the filter assembly comprising:
a) a first discrete physical filter media having an upstream face and a downstream face; and,
b) a second discrete physical filter media having an upstream face and a downstream face,
wherein the first discrete physical filter media extends around the second discrete physical filter media and wherein the filter assembly inhibits air bypassing the first discrete physical filter media as the air travels to the second discrete physical filter media, and
wherein a compressive force produced by the first and second discrete filter media maintains the first discrete physical filter media in position with respect to the second discrete physical filter media.
18. The surface cleaning apparatus of claim 17 wherein the upstream face of the second discrete physical filter media is spaced from and faces the downstream face of the first discrete physical filter media.
19. The surface cleaning apparatus of claim 17 wherein each of the first and second discrete physical filter media has a diameter and the diameter of the first discrete physical filter media is up to 25% larger than the diameter of the second discrete physical filter media.
20. The surface cleaning apparatus of claim 17 wherein each of the first and second discrete physical filter media have an average pore size and the average pore size of the second discrete physical filter media is smaller than the average pore size of the first discrete physical filter media.