Multistage cyclone and surface cleaning apparatus having same
A surface cleaning apparatus includes an air flow path, a cyclone, and an air flow passage. The air flow path extends from a dirty air inlet to a clean air outlet. A suction motor is positioned in the air flow path. The cyclone is positioned in the air flow path, and has a cyclone chamber, a cyclone chamber sidewall, a plurality of tangential air inlets, a cyclone air outlet, and a longitudinal cyclone axis. Air rotates in a direction of rotation in the cyclone chamber. Each tangential air inlets includes an inlet port provided in the cyclone chamber sidewall, each inlet port having an upstream edge and a downstream edge in the direction of rotation. The air flow passage extends parallel to the cyclone axis and upstream from the tangential air inlets. The air flow passage has a terminal end at which the plurality of tangential air inlets are located.
1. A surface cleaning apparatus comprising:
(a) an air flow path extending from a dirty air inlet to a clean air outlet with a suction motor positioned in the air flow path;
(b) a cyclone positioned in the air flow path, the cyclone having a cyclone chamber, a cyclone chamber sidewall, a plurality of tangential air inlets, a cyclone air outlet and a longitudinal cyclone axis about which the air rotates in the cyclone chamber, the cyclone chamber having a length in a direction of the longitudinal cyclone axis wherein air rotates in a direction of rotation in the cyclone chamber, each of the tangential air inlets comprises an inlet port provided in the cyclone chamber sidewall, each inlet port has an upstream edge and a downstream edge in the direction of rotation; and,
(c) an air flow passage extending parallel to the cyclone axis and upstream from the tangential air inlets, the air flow passage having a terminal end at which the plurality of tangential air inlets are located,
wherein each of the tangential air inlets has a terminal end wall and a flow directing member is provided at the downstream edge of one of the air inlet ports, the flow directing member extends longitudinally from the terminal end wall and also extends into the air flow passage.
2. The surface cleaning apparatus of claim 1 wherein the flow directing members are generally linear.
3. The surface cleaning apparatus of claim 1 wherein the flow directing members are configured to induce a rotational air flow within the cyclone chamber.
4. The surface cleaning apparatus of claim 1 wherein the flow directing members have a directing surface that generally faces an air flow in the air flow passage.
5. The surface cleaning apparatus of claim 1 wherein the air flow in the air flow passage comprises a rotational flow.
6. The surface cleaning apparatus of claim 1 wherein the air flow passage is positioned exterior to the cyclone chamber sidewall.
7. The surface cleaning apparatus of claim 6 wherein the cyclone is a downstream cyclone and a portion of the air flow passage is positioned between the cyclone chamber sidewall and a screen for an upstream cyclone.
8. The surface cleaning apparatus of claim 7 wherein the downstream cyclone is at least partially nested in the upstream cyclone.
9. The surface cleaning apparatus of claim 8 wherein the downstream cyclone is fully nested in the upstream cyclone.
10. The surface cleaning apparatus of claim 7 wherein the air flow passage has a passage length in the longitudinal direction, the screen has a screen length in the longitudinal direction, the downstream cyclone has a cyclone length in the longitudinal direction and each of the passage length and the screen length are at least 50% of the cyclone length.
11. The surface cleaning apparatus of claim 1 wherein the cyclone comprises 4 to 8 cyclone air inlets.
12. The surface cleaning apparatus of claim 1 wherein a combined cross-sectional area of the cyclone air inlets in a direction transverse to a flow direction therethrough is about equal to a cross sectional area of the cyclone air outlet in a direction transverse to a flow direction therethrough.
13. The surface cleaning apparatus of claim 7 wherein a combined cross-sectional area of the cyclone air inlets in a direction transverse to a flow direction therethrough is about equal to a cross sectional area of a cyclone air inlet of the upstream cyclone in a direction transverse to a flow direction therethrough.
14. The surface cleaning apparatus of claim 1 wherein the cyclone air outlet is located at a same end of the cyclone as the cyclone air inlets.
15. A surface cleaning apparatus comprising:
(a) a first stage cyclone having a first stage cyclone chamber, a first stage cyclone air inlet, a first stage cyclone air outlet and a first stage longitudinal cyclone axis about which the air rotates in the first stage cyclone chamber, the first stage cyclone air outlet comprising a longitudinally extending screen;
(b) a second stage cyclone downstream from the first stage cyclone and at least substantially nested in the first stage cyclone, the second stage cyclone having a second stage cyclone chamber, a second stage cyclone chamber sidewall, a plurality of second stage tangential air inlets, a second stage cyclone air outlet and a second stage longitudinal cyclone axis about which the air rotates in the second stage cyclone chamber, the second stage cyclone chamber having a length in a direction of the longitudinal cyclone axis wherein air rotates in a direction of rotation in the cyclone chamber, each of the tangential air inlets comprises an inlet port provided in the cyclone chamber sidewall, each inlet port has an upstream edge and a downstream edge in the direction of rotation; and,
(c) an air flow passage positioned between the screen and the second stage cyclone chamber sidewall, the air flow passage having a terminal end at which the plurality of tangential air inlets are located,
wherein each of the tangential air inlets has a flow directing member that is provided at the downstream edge of one of the air inlet ports and that extends into the air flow passage.
16. The surface cleaning apparatus of claim 15 wherein the air flow in the air flow passage comprises a rotational flow and the flow directing members have a directing surface that generally faces an air flow in the air flow passage.
17. The surface cleaning apparatus of claim 15 wherein a combined cross-sectional area of the second stage tangential air inlets in a direction transverse to a flow direction therethrough is about equal to a cross sectional area of the second stage cyclone air outlet in a direction transverse to a flow direction therethrough.
18. The surface cleaning apparatus of claim 15 wherein a combined cross-sectional area of the second stage tangential air inlets in a direction transverse to a flow direction therethrough is about equal to a cross sectional area of the first stage cyclone air inlet in a direction transverse to a flow direction therethrough.
19. The surface cleaning apparatus of claim 15 wherein the second stage cyclone air outlet is located at a same end of the second stage cyclone as the second stage tangential air inlets.