Abstract:
The invention relates to a cyclonic dirt separator comprising a dirt-collection assembly including a dirt tank having an inlet aperture and an outlet aperture, a cyclonic separator, at least one filter element, and a suction source fluidly connected with the dirt collection assembly. In one embodiment, the cyclonic dirt separator includes a separator plate cooperating with the housing to form a toroidal region of the dirt tank for aiding in the separation of dirt from a suction airstream developed by the suction source. The separator plate has an outer diameter smaller than the inner diameter of the dirt tank, creating a gap between the outer edge of the separator plate and the inner wall of the dirt tank. A further embodiment includes fins projecting from a sidewall of the dirt tank, and fingers projecting from a bottom wall of the dirt tank, to reduce re-entrainment of dirt particles.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to suction cleaners, and in particular to a separator for a suction cleaner. In one of its aspects, the invention relates to a separator with a cyclonic airflow path to separate dirt and debris from air drawn into the cleaner. In another of its aspects, the invention relates to a separator that deposits the dirt and debris in a collection receptacle. In another of its aspects, the invention relates to a separator including structure for inhibiting the re-entrainment of debris that vacillates with upward airflows in the collection receptacle. 
     2. Description of the Related Art 
     Cyclone separators are well known. Some follow the textbook examples using frusto-conical shape separators and others use high-speed rotational motion of the air/dirt to separate the dirt by centrifugal force. Separation of the dirt/dust from the air is not difficult, but the problem of keeping the dirt separated from the airflow has not been adequately solved. There is a tendency for the separated debris to re-entrain into the airflow and thereby pass through the separator. Some minor amounts of fine dust usually do get through the cyclone and are filtered in secondary filters downstream to maximize dust removal. These filters are positioned anywhere from the cyclone exit port to the clean air exhaust port. 
     The U.S. Pat. No. 6,260,234 to Wright attempts to solve the re-entrainment problem by placing a main filter in the cyclonic chamber. In this case, the main filter becomes the main separator and re-entrainment becomes a non-issue. This technique is similar to the filters in utility vacuums; however this approach creates a new problem of blinding the filter. The main filter must be cleaned or replaced frequently due to poor cyclone separation and creates a customer satisfaction problem. 
     The U.S. Pat. No. 6,221,134 to Conrad et al. discloses another attempt to reduce re-entrainment in a cyclone separator. Conrad et al. disclose a particle-receiving chamber beneath the cyclonic fluid flow region by adding a particle-separating plate that extends across the width of the separator chamber and has a plurality of narrow slots. Even though there continues to be rotational motion in the receiving chamber, the particles find it difficult to re-entrain into the airflow. However, this technique also has a problem. Not all the dirt is small enough to pass through the slots and dirt accumulates in the slots and plugs the slots. This means that a significant amount of debris remains in the cyclonic fluid flow region and is subject to re-entrainment. 
     The U.S. Pat. No. 6,228,151 to Conrad et al. discloses yet another attempt to reduce re-entrainment in a cyclone separator. In this separator, a plurality of vertical radial vanes extends from the bottom of an outer wall of the separator to a central portion of the separator. A cap covers a significant portion of the inner radial length of the vanes. 
     The Holm-Hansen et al. U.S. Pat. No. 2,071,975 discloses a vacuum cleaner with a separate dust separator that includes a conical casing in which the dust is separated from air by centrifugal force and a dust receptacle separated from the conical casing by a plate that extends radially from the center of the separation chamber toward the wall of the conical casing. Particles that are separated from air in the conical casing pass through the annular space between the outer wall of the chamber and the outer edge of the plate and into the dust receptacle. A tubular member in the center of the conical casing is formed from four overlapping curved metal strips between which the separated air passes to exit the separator. A pair of parallel, horizontally disposed foraminous screens are mounted in the bottom of the dust receptacle to facilitate settling of the dust. 
     SUMMARY OF THE INVENTION 
     According to the invention, a vacuum cleaner comprises a housing defining a cyclonic airflow chamber for separating contaminants from a dirt-containing airstream and a cyclonic chamber inlet and an airstream outlet in fluid communication with said cyclonic airflow chamber. The vacuum cleaner includes a nozzle housing having a suction opening fluidly connected with the cyclonic chamber inlet, and an airstream suction source fluidly connected to the main suction opening and to the cyclonic airflow chamber for transporting dirt-containing air from the suction opening to the cyclonic airflow chamber. The suction source is adapted to establish and maintain a dirt-containing airstream from the suction opening to the cyclonic chamber inlet. 
     A dirt-collecting bin is mounted beneath the cyclonic airflow chamber and includes a bottom wall and a cylindrical sidewall. A separator plate between the cyclonic airflow chamber and the dirt-collecting bin separates the cyclonic airflow chamber from the dirt-collecting bin. The separator plate has a diameter less than a diameter of the cyclonic airflow chamber adjacent the separator plate to thereby define a gap between the separator plate and the cyclonic airflow chamber for passage of dirt separated from the dirt-containing airstream in the cyclonic airflow chamber. The passage of dirt through the gap is accompanied by an airflow having horizontal and vertical components between the gap and the bottom wall of the dirt-collecting bin, which airflow tends to entrain dirt particles therein. It is believed that this airflow may be elliptical in form. 
     Airflow inhibitors are present in the dirt-collecting bin to reduce the vertical component of the airflow, thereby tending to agglomerate and separate the dirt particles from the airflow. 
     In one embodiment, the flow inhibitors comprise at least one prong extending upwardly from the bottom wall of the dirt-collecting bin and positioned radially between a center of the dirt-collecting bin and the sidewall thereof. Preferably, the airflow inhibitors comprise a plurality of said prongs each positioned radially between a center of the dirt-collecting bin and the sidewall thereof. The prongs extend a portion of the distance between the bottom wall and the separator plate. Further, the prongs are rectangular in cross section with a long axis radially disposed in the dirt-collecting bin. 
     In another embodiment, the airflow inhibitors further comprise at least one fin that extends radially inwardly from the sidewall of the dirt-collecting bin. Preferably, there are two and only two fins. The fins are generally positioned vertically below the inlet. The fin or fins extend a portion of the distance between the bottom wall and the separator plate. The fin or fins extend between 40% and 60% of the distance between the bottom wall and the separator plate. Generally, the fins have a radial dimension between 2% and 10% of the radius of the dirt-collecting bin, preferably, between 3% and 6% of the radius of the dirt-collecting bin. In a specific embodiment, the fins have a radial dimension equal to about 4% of the radius of the dirt-collecting bin. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings: 
     FIG. 1 is a perspective view of an upright vacuum cleaner with cyclone separator according to the invention. 
     FIG. 2 is a cut-away perspective view of the cyclonic separator of FIG.  1 . 
     FIG. 3 is a front cross-sectional view of the cyclonic separator of FIGS. 1-2. 
     FIG. 4 is a cross-sectional view taken through line  4 — 4  of FIG.  3 . 
     FIG. 5 is a cross-sectional view taken through line  5 — 5  of FIG.  3 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     An upright vacuum cleaner  10  with cyclonic dirt separator  550  and dirt cup  560  according to the invention is shown in FIG. 1, comprising an upright handle  12  pivotally mounted to a nozzle base  14 . The upright handle  12  mounts the cyclonic dirt separator  550  and dirt cup  560  according to the invention. 
     Referring to FIG. 2, cyclonic dirt separator and dirt cup assembly  51  according to the invention comprises a cylindrical cyclone separator  550  having an upper wall  142  and a sidewall  144 , the sidewall  144  terminating in a lower offset lip  146 . An annular collar  148  depends from upper wall  142 , the collar  148  being centered in the cylindrical cyclone separator  550 . An exhaust outlet  154  in the upper wall  142  and within the annular collar  148  is fluidly connected with a suction source (see FIG.  3 ). Sidewall  144  further includes a tangential air inlet  152  aligned proximate the upper wall  142  for generating a tangential airflow in the separator  550  parallel to the upper wall  142 . 
     The cyclonic dirt separator  550  further comprises a filter assembly  568 . The filter assembly  568  comprises a cylindrical arrangement of louvers  570  depending from the collar  148  that depends from upper wall  142  of the chamber  150 , and terminating in a lower annular collar. 
     Referring to FIGS. 3-4, a thick-walled cylindrical foam-type filter element  572  is arranged within the cylinder formed by louvers  570  and is held in place by a filter cage  574 . The filter cage  574  includes a perforate cylindrical wall formed on a solid separator plate  158 , and includes a centrally disposed locking insert  576  projecting upwardly within the cylinder of the wall for mounting the cage  574  to the cyclone separator  550 . A filter cage mounting projection  578  depends from upper wall  142  of cyclone separator  550 , within the cylinder formed by louvers  570 , to cooperate with locking insert  576  for mounting cage  574  to cyclonic dirt separator  550  in a substantially sealing fashion. The foam-type filter element  572  is thereby retained between the cage  574  and the louvers  570 . Any air passing from cyclone separator  550  to exhaust outlet  154  must thereby pass through foam-type filter element  572 . 
     Also in this manner, separator plate  158  is suspended from upper wall  142 , forming a toroidal chamber  180  between the cylindrical arrangement of louvers  570  and the sidewall  144 , and between the upper wall  142  and the separator plate  158 , respectively. In the preferred embodiment, air inlet  152  is vertically aligned between upper wall  142  and separator plate  158  such that the tangential airflow generated from tangential air inlet  152  is directed into the toroidal chamber  180 . 
     With further reference to FIGS. 2-4, the tangential airflow, containing particulate matter, passes through tangential air inlet  152  and into toroidal chamber  180  to travel around the filter assembly  568 . As the airflow travels about the toroidal chamber  180 , heavier dirt particles are forced toward sidewall  144 . These particles fall under the force of gravity through a gap  166  defined between an edge  162  of separator plate  158  and the sidewall  144 . Referring particularly to FIG. 3, dirt particles falling through the gap  166  drop through the open end  156  of separator  550  and are collected in the dirt cup  560 . The upper end of dirt cup  560  is received in a nesting relationship in lower offset lip  146  of the sidewall  144  to seal the cyclone separator  550  to the dirt cup  560 . Dirt cup  560  thereby performs the function of collecting the dirt separated from the airflow within the cyclone separator  550 . 
     As the inlet air traverses through toroidal chamber  180 , casting dirt particles toward sidewall  144 , the inlet air will be drawn inwardly between louvers  570 . As seen in FIG. 4, louvers  570  are oriented away from the direction of air flow (indicated by arrows) about toroidal chamber  180 . The velocity of the air flow is altered as the air flow changes direction to pass around and between louvers  570 . This change in the velocity of the air flow causes it to shed additional dirt particles. These dirt particles are urged toward the gap  166  by the circulating air flow in cyclone separator  550 . 
     The portion of the air flow that passes between louvers  570  then passes through the foam-type filter element  572 , which is composed to filter dirt of a selected particle size. The air then flows through exhaust outlet  154 , exhaust/suction conduit  196 , through a secondary (pre-motor) filter  192  to the suction source  190 . The secondary filter  192  removes additional particulate matter from the exhaust airstreams prior to the airstreams being drawn through the suction source  190 . A post-motor filter  194  can also be provided downstream of the suction source  190  to remove additional fine particulate matter from the exhaust airstream before it is released to the atmosphere. 
     Referring now to the dirt cup  560  shown in FIGS. 2-5, dirt cup  560  is formed with a generally planar bottom wall  582  and an upstanding cylindrical sidewall  584  to form an open-topped receptacle. A plurality of upstanding prongs or fingers  580  project upwardly from bottom wall  582 . The fingers  580  can function in varying arrangements, but in the preferred embodiment are arranged generally symmetrically about a circle concentric with sidewall  584 . The fingers  580  are further found to function best when displaced at least some distance from the center of the dirt cup  560 . Each of the fingers  580  are shown as being generally rectangular in plan view, having a long axis of its plan cross-section aligned with a radius of the circle. The fingers  580  can be of uniform cross-section from top to bottom, or can have a tapering cross-section as depicted in FIG. 3, wherein the fingers  580  are narrower at the top and wider at the base where they join the bottom wall  582 . The fingers  580 , as shown in the FIGS. 2-3, are approximately one half the height of the dirt cup  560 . Increasing the height of fingers  580  is preferred, but can be limited by production and tooling constraints and, as will be further described, the need to be able to detach dirt cup  560  from cyclone separator  550 . 
     The dirt cup  560  further includes a pair of fins  586 ,  588  affixed to and contiguous with sidewall  584 . Fins  586 ,  588  are generally rectangular in cross-section, in plan view, projecting inwardly from sidewall  584  toward a center of dirt cup  560 . The distance fins  586 ,  588  project from sidewall  584  can range from 2% to 10% of the radius, but is preferably 3% to 6% of the radius, and optimally 4% of the radius of the dirt cup  560 . Fins  586 ,  588  extend generally upwardly from bottom wall  582  of dirt cup  560 . In the preferred embodiment, fins  586 ,  588  are perpendicular to bottom wall  582  and extend approximately one-half of the height of dirt cup  560 , although fins  586 ,  588  can vary in height from 40% to 60% of the distance from bottom wall  582  to separator plate  158  and still be effective. Also in the preferred embodiment, fins  586 ,  588  are generally aligned in the direction of inlet airflow entering cyclone chamber  150  through air inlet  152 . As shown in FIG. 5, fins  586 ,  588  are arranged with respect to a radial  590  perpendicular to the tangential alignment of inlet  152 , with fin  586  angularly displaced from radial  590  by angle cc and fin  588  displaced from radial  590  by angle β. These angles can vary over a range of about 10° to 45°, and preferably in the range of 15° to 25°. It has been found that a satisfactory placement of the fins results when the angle α is about 19° to 20° and the angle β is about 19° to 20°. 
     A known phenomenon in cyclone separators is the re-entrainment of dirt into the cyclonic airflow after it is apparently deposited in a dirt containment vessel positioned beneath the cyclone chamber. It has been discovered that this re-entrainment is due to the vertical component of air circulation within the dirt cup between the gap  166  at one side of the dirt-collecting bin and the bottom wall  582  at an opposite side of the dirt-collecting bin. Generally, the airflow pattern has the strongest vertical component at the bottom portion of the dirt-collecting bin  560  below the inlet  152  to the cyclone chamber  550 . This air circulation is shown in phantom lines in FIG.  3 . 
     These vertical components of the air circulation are manifested in the “vacillating” of the dirt deposited within the dirt cup  560 . Disruption of, or a decrease in the magnitude of, these vertical components or vectors serves to minimize the re-entrainment of dirt in the cyclonic airflow and agglomeration of the dirt in the dirt cup. Disruption of the airflow tends to agglomerate the dirt particles in the dirt cup  560 , forming clumps or balls unlikely to be re-entrained. It has been found that fingers  580  and fins  586 ,  588  function in concert to inhibit the vacillation of the debris deposited in dirt cup  560 , disrupting the elliptical vectors that generate upward currents that would tend to carry the smaller dirt particles upwardly and back into the cyclonic air flow. Fingers  580  further deflect dirt particles within the dirt cup  560  to further encourage agglomeration of the dirt particles. Fingers  580  are generally arranged symmetrically about dirt cup  560 , but have been found to cooperate with fins  586 ,  588  optimally when none of fingers  580  are directly aligned with either of fins  586 ,  588 . 
     Dirt cup  560  is removably connected to separator  550 . Dirt cup  560  is generally vertically adjustable relative to cyclone separator  550 , such as by a cam mechanism on a vacuum cleaner, so that it can be raised into an engaged and operative position underneath the cyclone separator  550 . Upper edge of sidewall  584  is received within offset lip  146 , which prevents dirt cup  560  from being dislodged from cyclone separator  550 . To remove dirt cup  560  from cyclone separator  550 , such as to discard accumulated dirt, dirt cup  560  is displaced downwardly from cyclone separator  550 . Once disengaged from offset lip  146 , dirt cup  560  can be removed from separator  550 . 
     While the invention has been specifically described in connection with certain specific embodiments thereof, it is to be understood that this is by way of illustration and not of limitation. Reasonable variation and modification are possible within the forgoing disclosure and drawings without departing from the spirit of the invention which is defined in the appended claims.