Vacuum cleaner

Abstract

A vacuum cleaner (1) comprises an inlet (13), an outlet, a fan (14) for creating a flow of air through the vacuum cleaner (1) by drawing air to be cleaned through the inlet (13) into the vacuum cleaner (1) and by exhausting air through the outlet outwardly of the vacuum cleaner (1) and a separator (15, 41). The separator (15, 41) is rotatably arranged around an rotation axis (21), for creating, during use, a column of rotating air to separate at least a portion of the airborne particles (10) from the flow of air. The separator (15, 41) includes a number of vanes (25, 44) for the creation of the column of rotating air, wherein each vane (25, 44) is provided with a leading face (26) and a trailing face (27). The leading faces (26) of the vanes (25, 44) are inclined with respect to the rotation axis (21) for conveying the airborne particles (10) at least in an axial direction.

Claims

1. A vacuum cleaner, comprising: an inlet for receiving air to be cleaned, said air including airborne particles; an outlet for expelling received air externally of the vacuum cleaner; a fan for producing a flow of air through the vacuum cleaner by drawing the air to be cleaned through the inlet into the vacuum cleaner and by exhausting air through the outlet; and a separator rotatably arranged around a rotation axis for, during operation, producing a column of rotating air for separating at least a portion of the airborne particles from the flow of air, the separator including a plurality of vanes for producing the column of rotating air, each of said vanes having a leading face and a trailing face, where the leading faces of the vanes are inclined with respect to the rotation axis for conveying the airborne particles along a path that is at least partially in an axial direction and leads to a zone where a ratio of drag forces tending to guide the airborne particles into the separator relative to centrifugal forces tending to expel said airborne particles away from the separator is smaller than said ratio outside of said zone and where each leading face has a first portion and a second portion, said first portion being inclined in a positive direction and said second portion being oppositely inclined in a negative direction, for guiding airborne particles along said path.

2. A vacuum cleaner according to claim 1 where the fan is coaxially arranged with the separator, each vane having a proximal and a distal end, the proximal ends being between the fan and the distal ends, and where the leading faces are inclined with respect to the rotation axis in a direction for guiding airborne particles towards the distal ends.

3. A vacuum cleaner according to claim 1 where the separator comprises at least one plate extending perpendicular to the rotation axis, the vanes being arranged on at least one side of the plate, and where the leading faces of the vanes are inclined for conveying the airborne particles in an axial direction towards the plate.

4. A vacuum cleaner according to claim 1 where the separator comprises first and second plates extending perpendicular to the rotation axis, said plates being connected to opposite axial ends of the vanes, and where the opposite axial directions extend towards the opposite axial ends.

5. A vacuum cleaner according to claim 3 where the at least one plate has a radius, said radius being larger than a maximum distance between a tip of the vanes and the rotation axis.

6. A vacuum cleaner according to claim 1 where, in at least one plane perpendicular to the rotation axis, each vane is curved from an inner edge to an outer edge in a direction opposite to the direction of rotation and where the inner edge is located closer to the rotation axis than the outer edge.

7. A vacuum cleaner according to claim 1 where each of the vanes has a portion that is helically arranged.

8. A vacuum cleaner according to claim 1 where each inclined leading face has an angle with respect to the rotation axis, said angle increasing along a length of the leading face in the axial direction into which the airborne particles are forced by the inclined faces.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will be explained in more detail with reference to the drawings, in which

(2) FIG. 1 is a schematic cross section of a vacuum device according to the invention,

(3) FIG. 2 is a schematic perspective view of a separator of the vacuum device as shown in FIG. 1,

(4) FIG. 3 is an enlarged side view of a part of the separator as shown in FIG. 2,

(5) FIGS. 4A and 4B are enlarged bottom views of a part of the separator as shown in FIG. 2,

(6) FIG. 5 is an enlarged side view of a part of a separator of another embodiment of the vacuum device according to the invention.

(7) FIG. 6 is a schematic representation of a vane.

(8) Like parts are indicated by the same reference numbers in the figures.

DETAILED DESCRIPTION OF EMBODIMENTS

(9) In FIG. 6 a cross-section of a vane 25 of a separator 15 is schematically depicted. The vane 25 is rotating in a clockwise direction around an axis of rotation 21 of the separator 15. The direction of rotation is indicated by a curved arrow R. A practical embodiment of the separator 15 is in general equipped with a number of such vanes; however, in FIG. 6 only one vane is depicted. If a trajectory 32 of an air molecule flowing into the separator, i.e. a flow line, is considered, a distinction can be made between a so-called leading face 26 and trailing face 27 of the vane 25. This leads to a side or part of the vane that first approaches the air flowing along flow line 32 when the separator is rotating; this side is referred to as the leading face of the vane. As the air continues its path around the vane it will subsequently reach the other side of the vane which is referred to as the trailing face 27 of the vane. The leading face 26 of a vane is the side of the vane which faces the air that flows towards the separator and the vane; the trailing face 27 of a vane is the rearmost side of the moving vane as seen in the direction of the airflow.

(10) FIG. 1 shows a vacuum cleaner 1 comprising a housing 2 in which two brushes 3, 4 are rotatably mounted around axles 5, 6. The brushes 3, 4 are driven by a motor (not shown). The brush 3 is rotatable in a clockwise direction, indicated by arrow P3 and the brush 4 is rotatable in a counter clockwise direction, indicated by arrow P4 around the respective horizontal axles 5, 6. The brushes 3, 4 are fully enclosed except at the bottom by the housing 2. The housing 2 is provided with wheels (not shown) keeping the axles 5, 6 at a predetermined distance of the surface to be cleaned. The housing 2 is provided with a handle 7 at a side remote of the brushes 3, 4. Between the handle 7 and the brushes 3, 4 the vacuum cleaner 1 is provided with a reservoir 8 for a cleansing fluid like water and a debris collecting container 9 for fluid and particles 10 picked up from the surface 11 to be cleaned. The debris collecting container 9 is provided with a hollow tube 12 extending from an air inlet opening 13 between the brushes 3, 4 into the debris collecting container 9. At a side of the debris collecting container 9 opposite the tube 12 there is provided a vacuum fan 14 and a rotatable separator 15.

(11) In use, the vacuum cleaner 1 is being moved in a direction as indicated by arrow P1 over the surface to be cleaned 11. During said movement, the brushes 3, 4 are being rotated in the opposite directions P3, P4 directed towards each other near the surface to be cleaned 11. Cleansing fluid from the reservoir 8 is applied via the brush 3 on the surface 11. By moving the brushes 3, 4 over the surface to be cleaned 11 particles like dirt and other materials are being disconnected from the surface 11. Simultaneously, the surface 11 is being cleaned by the cleansing fluid. By further moving the vacuum cleaner 1 in the direction as indicated by arrow P1, the disconnected particles 10 and the cleansing fluid on the surface are being moved upwards into the air inlet opening 13 due to the rotational movement of the brushes 3, 4, i.e. the fluid and particles 10 picked up from the surface 11 to be cleaned will become airborne. Furthermore, the air with the airborne particles 10 and cleansing fluid is being moved from the air inlet opening 13 into the tube 12 towards the debris collecting container 9 by means of the vacuum fan 14. In the debris collecting container 9 most of the particles will fall directly downwards towards the bottom of the debris collecting container 9 into dirty fluid 16 that has already been picked up or that was already present in the container 9. Instead of falling directly to the bottom of the container 9 there are also particles that tend to move towards the vacuum fan 14. These particles that tend to move upwards to the fan 14 are prevented there from by the separator 15 which acts counterproductive to the vacuum fan 14. The relatively heavy particles will be moved away from the separator 15 and will fall downwards into the dirty fluid 16. The relatively light air will pass the separator 15 and be moved through the vacuum fan 14 and the cleaned air will leave the vacuum cleaner via an air outlet opening.

(12) FIGS. 2-4B show different views of the separator 15 being rotatable about a rotation axis 21. The separator 15 comprises two round plates 22, 23 having different diameters. The central axis of the plates 22, 23 forms the rotation axis 21. The plate 22 is of a smaller diameter than plate 23 and is provided with a centrally located hole 24. This plate 22 is located closer to the vacuum fan 14 than the plate 23. The plates 22, 23 are located at a distance of each other and are connected to each other by means of vanes 25. Each vane 25 has a leading face 26 and a trailing face 27 seen in the rotation direction R (FIGS. 2, 4A, 4B). As can be seen in FIG. 3, the vanes 25 are inclined with respect to the rotation axis 21 and the leading face 26 encloses an angle A with the plate 23. Each vane 25 is curved from an inner edge 28 to an outer edge 29 in a direction opposite to the rotation direction R, wherein the inner edge 28 is located closer to the rotation axis 21 than the outer edge 29. Between the vanes 25 passages 30 are present through which air will flow from the debris collecting container 9 towards the vacuum fan 14 in a direction as shown by arrow P1 (FIG. 2).

(13) When rotating the separator 15 about the rotation axis 21 in the rotation direction R, a column of rotating air will be created by the high-speed rotation of the separator 15. The air having a low specific mass compared to the dirt and particles which are airborne therein is dragged into the separator 15 by drag forces caused by the vacuum generated by the vacuum fan 14. The airborne particles are also dragged towards the separator 15 along with the air into which they are airborne. In the vicinity of the separator 15 the airborne particles enter into the column of rotating air. On top of the drag forces which convey the particles towards the separator 15 and into the column of rotating air, the airborne particles are being subjected to centrifugal forces due to the action of the column of rotating air.

(14) In FIG. 4B, a relative velocity profile v.sub.air of air and airborne particles in the passage 30 between a trailing face 27 of one vane 25 and the leading face 26 of another vane 25 is indicated relative to the vane 25. As will be appreciated by the skilled person this velocity is relative to the trailing face because the vanes are rotating at high angular velocity. As can be seen, the velocity at the leading face 26 is much smaller than at the trailing face 27.

(15) In FIGS. 4A and 4B a trajectory 32 of an air molecule 31 flowing into the separator 15 is shown. After being lead to the leading face 26, the air molecule 31 will flow around the outer edge 29 towards the trailing face 27. It will then flow through the passage 30 and through the hole 24 (FIG. 2) towards the vacuum fan 14. A heavier airborne particle 10 will be subjected to the drag forces and the centrifugal forces. If the centrifugal forces outweigh the drag forces the airborne particle 10 is thrown out of the column of rotating air without flowing through the separator 15. The heavier particle 10 will follow the trajectory 32 towards the leading face 26 and away there from.

(16) Due to the curvature of the vanes 25 from the inner edge 28 to the outer edge 29 in a direction opposite to the rotation direction R, the leading faces 26 will also exert a pushing force on the particles 10 in a direction away from the rotation axis 21. A vane having this effect is known as a so-called non-catching vane.

(17) As can be seen in FIG. 3, the particles 10 will be directed by the inclined leading faces 26 of the vanes 25 in axial direction towards the plate 23 which is located further away from the vacuum fan 14 than the plate 22. Near the plate 23 the drag forces are lower than near the plate 22. Furthermore, the rotating plate 23 with the larger diameter will create a pumping effect on the air near the plate 23 in a direction away from the rotation axis 21. Due to the pumping effect, a pumping force will be exerted on the air and the airborne particles 10. This pumping effect counteracts the drag forces and helps the centrifugal forces emanating from the column of rotating air. Near the plate 23 the combination of centrifugal forces and pumping forces can easily outweigh the drag forces, so that also relatively light airborne particles will be thrown out of the column of rotating air down to the dirty water in the container 9 resulting into a successful separation.

(18) FIG. 5 shows a side view of a separator 41 of another embodiment of a vacuum cleaner according to the invention. The separator 41 comprises two plates 42, 43 and vanes 44 extending between the plates 42 and 43. Both plates 42 and 43 have a radius larger than the radius of the vanes 44. The vanes 44 are curved in a plane perpendicular to the rotation axis to provide the non-catching effect as described above according to a previous embodiment. The vanes 44 are also curved in a plane parallel to the rotation axis, as can be seen in FIG. 5. The curvature in the plane parallel to the rotation axis is such that the leading face 45 has a first portion 46 and a second portion 47, which are inclined in a positive direction and a negative direction respectively. Said positive and negative directions are opposite directions. Particles 10 are guided by either the first portion or the second portion of the leading face 45 of the vane 44 in opposite axial directions towards the plates 42, 43.

(19) It is also possible to use plates which have a shape other than round. However, given the fact that the separator has to provide separation at high angular velocities the plates should preferably not introduce too much unbalance.

(20) It is also possible to provide a number of separators 15 on top of each other wherein the centrally located hole 24 extends through all the plates except the plate directed towards the debris collecting container 9 to prevent air and airborne particles to directly enter hole 24.

(21) Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the words like comprising and having do not exclude other elements or steps, and the indefinite article a or an does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope.