Patent Publication Number: US-6209167-B1

Title: Hover vacuum cleaner

Description:
FIELD OF THE INVENTION 
     The present invention relates to vacuum cleaners, and more particularly to air-supported hover vacuum cleaners. 
     BACKGROUND TO THE INVENTION 
     Air-supported vacuum cleaners are known. For example, U.S. Pat. No. 2,751,038 to L. K. Acheson, which issued Jun. 19, 1956 discloses an air-supported vacuum cleaner which has an air space on the underside of the cleaner, which is bounded by the underside of the casing for the cleaner and a peripheral dam or bead. Other air-supported vacuum cleaners are shown in U.S. Pat. No. 2,780,826 to Coons et al., which issued Feb. 12, 1957, U.S. Pat. No. 3,283,355 to I. Jepson, which issued Nov. 8, 1966 and U.S. Pat. No. 2,889,570 to J. E. Duff, which issued Jun. 9, 1959. U.S. Pat. No. 2,743,787 to W. G. Seck, which issued May 1, 1956 discloses an air-supported vacuum cleaner which has an air space bounded by the underside of the casing for the cleaner and a peripheral dam. Outside the peripheral dam there is a deflector for preventing air from discharging across the surface of the floor upon which the vacuum cleaner rests or travels, and for directing the escaping air in an upward direction. 
     One of the problems with previous air-supported vacuum cleaners is a tendency for the vacuum cleaner to rock or judder as a result of uneven flow of air escaping from under the peripheral dam. One solution to this problem is disclosed in U.S. Pat. No. 2,814,064 to J. C. Montgomery, which issued Nov. 26, 1957 which discloses an air-supported vacuum cleaner with a peripheral double dam with an air diffusing channel between the dams. The air escapes from the air space, past the inner of the two dams and thence through the air diffusing channel. Such an arrangement adds to the cost of the vacuum cleaner and introduces complexity to the operation of the vacuum cleaner. The present invention is directed to a simple but effective air-supported vacuum cleaner which tends to be stable, not subject to juddering and is relatively inexpensive to produce. The invention is also directed to a hover vacuum cleaner with an arrangement which the hover performance tends not to diminish as the filter becomes filled with dust. 
     SUMMARY OF THE INVENTION 
     The present invention provides a vacuum cleaner comprising: 
     a casing, an underside to the casing in which the underside has a longitudinal axis, an impeller and drive motor for the impeller, a dust filter, an inlet for dust laden air, an exhaust port in the, a pathway for air to pass from the inlet, through the dust filter and impeller and around the motor, and through the exhaust port; 
     wherein the underside has dished air chambers, covering a substantial area of the underside, in locations selected from the group consisting of i) at least two dished air chambers on the underside, wherein each dished air chamber straddles the longitudinal axis, and adjacent dished air chambers are separated by a dam which is transverse to the longitudinal axis, and wherein the exhaust port is in direct fluid communication with one of the dished air chambers and the exhaust port straddles the longitudinal axis, ii) a first dished air chamber which straddles the longitudinal axis and an exhaust port which straddles the longitudinal axis, wherein the exhaust port is in direct fluid communication with the first air chamber, and at least one pair of dished air chambers wherein corresponding dished air chambers in each pair are on opposing sides of the longitudinal axis separated by a keel skirt, and wherein the first air chamber and the adjacent pair of dished air chambers are separated by a dam which is transverse to the longitudinal axis, and wherein the adjacent pairs of dished air chambers are separated by a dam which is transverse to the longitudinal axis; and 
     wherein the underside has a peripheral groove which is in fluid communication with a member selected from the group consisting of the exhaust port and the air chamber which is in direct fluid communication with the exhaust port, and a combination thereof. 
     In one embodiment, there are three dished air chambers, each of which straddle the longitudinal axis. 
     In a further embodiment, there are three dished air chambers, each of which straddles the longitudinal axis, and the air chamber in fluid communication with the exhaust port is an outer chamber. 
     In another embodiment, the underside of the vacuum has an extension which extends outwardly and upwardly from the peripheral groove, with the extension having an arcuate cross-section. 
     In yet another embodiment, the vacuum cleaner has a cyclonic action dust filter. 
     In a further embodiment, the inlet for dust laden air, which leads to the cyclonic action dust filter, has a nozzle which is rotatable about an axis which is parallel to a longitudinal axis for the dust filter. 
     In another embodiment, the inlet for dust laden air, which leads to the cyclonic action dust filter, has a nozzle which is rotatable so that the nozzle may direct air at any downward angle into the dust filter. 
     In yet another embodiment, the pathway for air from the impeller to the exhaust port is constrained by walls so that there is a steady flow of air therethrough when the vacuum is in operation. 
     In another embodiment, the walls are in a partial snail shell shape. 
     The present invention also provides a hover vacuum cleaner comprising: 
     a casing, an underside to the casing, a cyclonic dust filter, hover means on the underside to allow the vacuum cleaner to hover on a bed of air, an inlet to the cyclonic dust filter for dust laden air, an impeller and drive motor for the impeller, an exhaust port in the underside, a pathway for air to pass from the inlet, through the dust filter and impeller and around the motor, and through the exhaust port to the hover means. 
     In one embodiment, the inlet for dust laden air, which leads to the cyclonic action dust filter, has a nozzle which is rotatable about an axis which is parallel to a longitudinal axis for the dust filter. 
     In another embodiment, the inlet for dust laden air, which leads to the cyclonic action dust filter, has a nozzle which is rotatable so that the nozzle may direct air at any downward angle into the dust filter. 
     In yet another embodiment, the pathway for air from the impeller to the exhaust port is constrained by walls so that there is a steady flow of air therethrough when the vacuum is in operation. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a cross-sectional side view of a vacuum cleaner of the present invention. 
     FIG. 2 is a top view of the vacuum cleaner of FIG.  1 . 
     FIG. 3 is a bottom view of the vacuum cleaner of FIG.  1 . 
     FIG. 4 is a view showing the lid, inlet tube and the mouth of an inlet nozzle, also shown in FIG.  1 . 
     FIG. 5 is a cross-sectional side view of the vacuum cleaner of FIG. 1, showing air flows. 
     FIG. 6 is a bottom view of another embodiment of a vacuum cleaner. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     The drawings show a vacuum cleaner  10  which has an upper body casing  11  and a lower body casing  16  joined at joint  37 . Upper body casing  11  has an upper opening  12 . Opening  12  is for removing and replacing a filter within filter cavity  38 . Opening  12  is closed with lid  13 . Suction inlet tube  14  is connected to lid  13  by swivel bearing  35 . Suction inlet tube  14  leads through lid  13  into filter cavity  38  and terminates in opening  15  in nozzle  39 . 
     Located inside vacuum cleaner  10  is filter cavity  38  which is bounded by a filter container  43  (see FIG.  2 ), which comprises front wall  26  and rear perforated wall  27  (see FIG.  1 ). A filter bag  44  may be inserted into filter cavity, as is known in the art. Also located in upper body casing  11  is motor  28  and impeller  29 . Impeller  29  is positioned within vacuum cleaner  10  by means of wall  32 , which also serves to ensure that air is drawn by impeller  29  from the filter  44 . Impeller  29  has inlet apertures  41  and outlet apertures  40 . Outlet apertures lead into chamber  30  which surrounds motor  28 . As shown in FIG. 1, chamber  30  is bounded by chamber walls  31 . Chamber walls  31  allow for direction of a steady flow of air from outlets  40 , past motor  28 , to exhaust port  18  in the bottom of lower casing  16 . The chamber walls  31  are preferably in the shape of a partial snail shell, as shown in FIG.  1 . Chamber walls  31  avoid deadspots of air flow as in prior designs, in which air enters a large chamber before exiting through exhaust port  18 . The inlet  14  is connected to flexible tube  36 , which is connected to a power head (not shown), or other dust receiving tools as is known in the art. 
     Motor  28  is an electric motor and is electrically powered through electric cord  33 , which enters upper body casing  11  through a hole at the rear of the vacuum. Electric motor  28  is controlled by on-off switch  34 . The top of body casing  11  has a handle  42 . 
     The underside  17  of lower body casing  16  has three dished air chambers  21 ,  22  and  25 , each of which is symmetrical about, and straddles, longitudinal axis X—X. Air chamber  25  has exhaust port  18  therein. Air chambers  25  and  21  are separated by transverse bar  24 . Air chambers  22  and  21  are separated by transverse bar  23 . Around the periphery of underside  17  there is a channel  19  which connects with air chamber  25  by connecting passage  20 . In the embodiment shown, there is an arcuately shaped extension  46  which curves upwardly to the main part of casing  11 . While this is not essential, it has been found to be beneficial in helping the stability of the vacuum cleaner. 
     The placement of the dished air chambers  21 ,  22  and  25  need not be symmetrical about the longitudinal axis. Indeed, it has been found that at least one of the air chambers by be offset from the longitudinal axis, so that portion of the air chamber on one side of the longitudinal axis is larger than the portion on the opposing side of the longitudinal axis. The reason for this is not known, but in some instances it has been demonstrated to be beneficial. 
     It is preferable that the ratio of the total area of the dished air chambers to the total area of the underside be at least about 70:100 and preferably from about 75:100 to 95:100. 
     The inlet tube  14  is connected to lid  13  at a swivel bearing  35 , as shown in FIG.  4 . Inlet tube is in fluid connection with inlet nozzle  39 . Inlet nozzle  39  has an opening  15  through which dust laden air may be directed at an angle into filter cavity  38 . In the embodiment shown, inlet nozzle  39  may be swivelled in a 360° arc so that opening  15  may be directed towards any part of the upright wall of filter container  43 , e.g. rear wall  27  or front wall  26 . Preferably, the filter arrangement is a so-called cyclonic filter. Cyclonic filters are known and have previously been used in conventional vacuum cleaners with wheels. 
     In operation, when the motor  28  is energized, air is drawn through the vacuum cleaner by means of the impeller  29 , which is driven by motor  28 . Dust laden air is picked up by a power head or other tool (not shown) and is sucked into filter cavity  38  through flexible tube  36 , inlet tube  14  and nozzle  39 . Nozzle  39  directs the dust laden air into filter cavity  38  as indicated schematically by arrows A and B in FIG.  5 . Cyclonic action of the air permits the dust to drop out of the air flow, before being drawn through filter  44 , and into impeller  29  through passageway  41 . Air is then expelled by impeller  29  past motor  28  and into chamber  30 . In the embodiments shown in the drawings, the chamber  30  is bounded by walls  31 , which direct the filtered air past the motor housing and to exhaust port  18 . The walls  31  are not essential but have the benefits of preventing stagnation of air in chamber  30 , keeping a high airflow over the motor housing and thus keeping the motor cooler than would otherwise be the case. Without walls  31 , air tends to be compressed in chamber  30  and the air flow patterns are such that there is a heat build up in chamber  30 . 
     With respect to the dust laden air entering the filter cavity  38 , the flow of the air can be controlled by the angles of entry of the air through opening  15 , relative to directions parallel and transverse to the longitudinal axis Y—Y (see FIG. 5) of the filter cavity  38 , and the offset of the opening  15  from the longitudinal axis Y—Y. The angle of air flow and positioning of inlet nozzle  39  will affect the air flow pattern, and thus the cyclonic action, in filter cavity  38 . The cyclonic action tends to keep the walls of the filter bag  44  from being clogged. As will be appreciated, clogging of the walls of filter bag  44  would lead to a pressure drop and consequent lowering of the rate of air flow into the impeller. A particular advantage of the cyclonic air filter for a hover vacuum is that there is little lessening of air flow through the filter as the bag becomes filled with dust. Accordingly, the hover action of the vacuum cleaner tends not to be impaired as the filter becomes filled with dust. The cyclonic action of the filter improves the performance of hover vacuum cleaners with hover systems which are not shown in the drawings. For example, a cyclonic filter will improve the performance of hover vacuum cleaners as disclosed in the aforementioned U.S. Pat. No. 2,780,826 to Coons et al., U.S. Pat. No. 3,283,355 to I. Jepson and U.S. Pat. No. 2,889,570 to J. E. Duff, among others. 
     Although the drawings show the vacuum cleaner  10  as having a cyclonic action filter system, such a system is not necessary for the operation of one aspect of the invention. It is, however, especially preferred. 
     The hover action of the vacuum cleaner  10  is effected by air flow from exhaust port  18  across the underside  17 , before escaping from the periphery of the underside  17 . Without wishing to be held to any theory, Applicant believes that the peripheral channel  19  allows air to be directed in a peripheral “skirt”, while the dished air chambers  21  and  22  provide compression pockets at the forward end of the vacuum  10 . Without the peripheral channel, there is a tendency for the vacuum cleaner to judder and become unstable. The positioning of dams  23  and  24  between adjacent air chambers is critical to the hovering action of the vacuum cleaner. For example, it has been found that displacement of dam  23  by as little as 3-4 cm along the longitudinal axis X—X is sufficient to alter the air flow patterns so that the vacuum cleaner no longer hovers. Notwithstanding the criticality of the positioning, however, the correct positions for the dams can be found by simple experimentation. 
     The air flow patterns are shown schematically in FIGS. 3 and 5. Dust laden air flows through nozzle  39  as indicated by arrow A, before being directed in a vortex pattern B in filter cavity  38 . The air then passes through filter bag  44  and into impeller  29  as indicated by arrow C. The impeller then forces the air into air chamber  30  in the direction shown by arrow E and thence through exhaust port  18 , as shown by arrow D. After exiting through exhaust port  18 , some of the air is directed into channel  19  as shown by arrows M and K. Some of the air is also directed into dished air chamber  25  as shown by arrows F. The air swirls in chamber  25  as shown by arrows G. Some of this air spills over dams  24  and  23  and swirls in air chambers  21  and  22  as shown by arrows H and J respectively. The air then escapes from the underside  17  as indicated by arrows L. It will be recognized that the patterns shown may not be true representations of the air flow. 
     It has been found that, apart from the dished air chambers  21 ,  22  and  25 , channel  19  and the periphery of the underside, the remainder of the underside is preferably flat. 
     Another arrangement of dished air chambers on the underside of the vacuum cleaner may be as shown in FIG.  6 . As will be apparent, the difference between the underside of FIGS. 3 and 6 lies in the longitudinal division of dished air chambers  21  and  22  of FIG. 3 by a keel skirt. In FIG. 6, the keel skirt  45  separates dished air chambers  21   a  and  21   b , and  22   a  and  22   b . Other combinations of dished air chambers, dams and keel skirts are operable and these may be determined through simple experimentation. For example, there may only be one pair of dished air chambers  21   a  and  21   b  on opposing sides of longitudinal axis X—X. 
     The vacuum cleaner may be made using conventional materials. For example the casing, impeller walls and inlet tubing may be made from synthetic thermosetting or thermoplastic polymers, glass fibre reinforced plastic (FRP), metal or other suitable materials. 
     The vacuum cleaner may also have other features. For example, the electric cord  33  may be automatically retractable into the housing using a spring loaded reel. The filter housing may also have facility for inserting a pouch with fragrant material therein. 
     The vacuum cleaner of the present invention may be used on many types of floor surface, including carpeted surfaces. The vacuum works well on stairs also, as long as the whole of underside  17  remains on a stair step. If the vacuum cleaner works its way to an edge of the stair step sufficient for part of channel  19  to be unsupported by the stair, then air will be caused to spill at the unsupported part and thus cause the vacuum cleaner to lose its hovering action. In this way there is less likelihood of the vacuum cleaner from being dislodged from the stair than for conventional wheeled vacuum cleaners. 
     EXAMPLE 
     A hover vacuum cleaner was constructed substantially to the shape and design shown in FIGS. 3 and 5. The length direction given hereinafter is in the direction of longitudinal axis X—X and the width is transverse to the length. The exhaust port had a length of 3.8 cm and a width of 10.2 cm. Dished air chamber  25 , which emanated from exhaust port  18  had a length of 15.2 cm, a width of 11.4 cm and a depth of 0.5 cm. Dished air chamber  21  had a length of 3.8 cm, a width of 11.4 cm. and a depth of about 0.65 cm. Dished air chamber  22  had a length of 5.1 cm, a width of about 11.4 cm and a depth of about 0.65 cm. Exhaust port  18  and dished air chambers  25  and  21  were centred about longitudinal axis X—X and dished air chamber  22  was offset by about 0.95 cm. Dams  23  and  24  were about 0.95 cm between adjacent dished air chambers and the edges of dams  23  and  24  sloped into the adjacent dished air chambers to provide for smooth air flow over the dams. The ratio of the total area of the dished air chambers to the area of the underside was about 80:100. 
     In operation, the vacuum cleaner moved smoothly over carpeted and tiled floors while dust was being vacuumed from the floors.