US 20020148069 A1
Disclosed is an improved vacuum cleaner nozzle. The vacuum cleaner nozzle comprises two concentric tubes which guide fluid flow into toroidal vortex. The fluid flow creates a low pressure region such that dust, dirt, and a variety of other objects may be sucked up. The nozzle is designed to be used in conjunction with a vacuum cleaning system. The entire system is closed such that airflow is contained. Thus, the vacuum cleaner system is highly efficient and prevents dust from escaping into the atmosphere. Additionally, the toroidal vortex nozzle may be fitted with an additional sleeve to allow the nozzle to be placed against surfaces without impeding fluid flow. Furthermore, by venting the nozzle, undesired pluming in front of the nozzle can be prevented.
1. A toroidal vortex nozzle for guiding fluid flow comprising:
an outer tube;
an inner tube disposed inside said outer tube and further wherein the gap between said inner tube and said outer tube forms an annular duct; and
guide means to guide said fluid flow out said annular duct and in said inner tube;
wherein said fluid flow after traveling through said guide means has substantially the characteristics of a toroidal vortex.
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a vent in said outer tube; and
means to control the size of said vent.
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35. A nozzle for guiding a fluid flow comprising:
an inner tube;
an outer tube, said inner tube and said outer tube being concentric such that said inner tube and said outer tube form an annular duct;
wherein said fluid flows out of said annular duct and into said inner tube.
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45. A method of creating a toroidal vortex fluid flow comprising the steps of:
flowing a fluid through an annular duct created between concentric tubes; and
flowing said fluid back through the inner tube of said concentric tubes.
46. A method of creating a toroidal vortex fluid flow in accordance with
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 This application is a continuation-in-part of co-pending application entitled “Toroidal Vortex Bagless Vacuum Cleaner,” filed Apr. 13, 2001, which is a continuation-in-part of co-pending application entitled “Toroidal and Compound Vortex Attractor,” filed Apr. 9, 2001, which is a continuation-in-part of co-pending application Ser. No. 09/728,602, filed Dec. 1, 2000, entitled “Lifting Platform,” which is a continuation-in-part of co-pending Ser. No. 09/316,318, filed May 21, 1999, entitled “Vortex Attractor.”
 The present invention relates initially, and thus generally, to an improved vacuum cleaner nozzle. More specifically, the present invention relates to an improved vacuum cleaner nozzle that utilizes a toroidal vortex such that the airflow within the vacuum cleaner housing is contained therein. The present invention prevents dust-laden air within the device from being carried to the surrounding atmosphere.
 The use of vortex forces is known in various arts, including the separation of matter from liquid and gas effluent flow streams, the removal of contaminated air from a region and the propulsion of objects. However, cylindrical vortex flow has not previously been provided in a bagless vacuum device having light weight and high efficiency.
 The prior art is strikingly devoid of references dealing with toroidal vortices in a vacuum cleaner application. However, an Australian reference has some similarities. This Australian reference does not approach the scope of the present invention, it is worth disusing its key features of operation so that one skilled in the art can readily see how its shortcomings are overcome by that which is disclosed herein.
 In discussing Day International Publication number WO 00/19881 (the “Day publication”), an explanation of the Coanda effect is required. This is the ability for a jet of air to follow around a curved surface. It is usually referred to without explanation, but is generally understood provided that one makes use of “momentum” theory: a system based on Newton's laws of motion. Utilizing the “momentum” theory instead of Bernoulli's principles provides a simpler understanding of the Coanda effect.
FIG. 1 shows the establishment of the Coanda effect. In (A) air is blown out horizontally from a nozzle 100 with constant speed V. The nozzle 100 is placed adjacent to a curved surface 102. Where the air jet 101 touches the curved surface 102 at point 103, the air between the jet 101 and the surface 102 as it curves away is pulled into the moving airstream both by air friction and the reduced air pressure in the jet stream, which can be derived using Bernoulli's principles. As the air is carried away, the pressure at point 103 drops. There is now a pressure differential across the jet stream so the stream is forced to bend down, as in (B). The contact point 104 has moved to the right. As air is continuously being pulled away at point 104, the jet continues to be pulled down to the curved surface 102. The process continues as in (C) until the air jet velocity V is reduced by air and surface friction.
FIG. 2 shows the steady state Coanda effect dynamics. Air is ejected horizontally from a nozzle 200 with speed represented by vector 201 tangentially to a curved surface 203. The air follows the surface 203 with a mean radius 204. Air, having mass, tries to move in a straight line in conformance with the law of conservation of momentum. However, it is deflected around by a pressure difference across the flow 202. The pressure on the outside is atmospheric, and that on the inside of the airstream at the curved surface is atmospheric minus
 The vacuum cleaner Coanda application of the Day publication has an annular jet 300 with a spherical surface 301, as shown in FIG. 3. The air may be ejected sideways radially, or may have a spin to it as shown with both radial and tangential components of velocity. Such an arrangement has many applications and is the basis for various “flying saucer” designs.
 The simplest coanda nozzle 402 described in the Day publication is shown in FIG. 4. Generally, the nozzle 402 comprises a forward housing 407, rear housing 408 and central divider 403. Air is delivered by a fan to an air delivery duct 400 and led through the input nozzle 401 to an output nozzle 402. At this point the airflow cross section is reduced so that air flowing through the nozzle 402 does so at high speed. The air may also have a rotational component, as there is no provision for straightening the airflow after it leaves the air pumping fan. The central divider 403 swells out in the terminating region of the output nozzle 402 and has a smoothly curved surface 404 for the air to flow around into the air return duct using the Coanda effect.
 Air in the space below the Coanda surface moves at high speed and is at a lower than ambient pressure. Thus dust in the region is swept up 405 into the airflow 409 and carried into the air return duct 406. For dust to be carried up this duct, the pressure must be low and a steady flow rate must be maintained. After passing through a dust collection system the air is sent through a fan back to the air delivery duct. Constriction of the airflow by the output nozzle leads to a pressure above ambient in this duct ahead of the jet. In sum, air pressure within the system is above ambient in the air delivery duct and below ambient in the air return duct.
 Coanda attraction to a curved surface is not perfect. As shown in FIG. 5, not all the air issuing from the output nozzle is turned around to enter the air return duct. An outer layer of air proceeds in a straight fashion 501. When the nozzle is close to the floor, this stray air will be deflected to move horizontally parallel to the floor and should be picked up by the air return duct if the pressure there is sufficiently low. In this case, the system may be considered sealed; no air enters or leaves, and all the air leaving the output nozzle is returned.
 When the nozzle is high above the ground, however, there is nothing to turn stray air 501 around into the air return duct and it proceeds out of the nozzle area. Outside air 502, with a low energy level is sucked into the air return to make up the loss. The system is no longer sealed. An example of what happens then is that dust underneath and ahead of the nozzle is blown away. In a bagless system such as this, where fine dust is not completely spun out of the airflow but recirculates around the coanda nozzle, some of this dust will be returned to the surrounding air.
 Air leakage is exacerbated by rotation in the air delivery duct caused by the pumping fan. Air leaving the output nozzle rotates so that centrifugal force spreads out the airflow into a cone. The effect is to generate a higher quantity of stray air. Air rotation can be eliminated by adding flow straightening vanes to the air delivery duct, but these are neither mentioned nor illustrated in the Day publication.
 A side and bottom view of an annular Coanda nozzle 600 is shown in FIG. 6. This is a symmetrical version of the nozzle shown in FIG. 4. Generally, the nozzle 600 comprises outer housing 602, air delivery duct 601, air return duct 605, flow spreader 603 and annular Coanda nozzle 604. Air passes down though the central air delivery duct 601, and is guided out sideways by a flow spreader 603 to flow over an annular curved surface 604 by the Coanda effect, and is collected through the air return duct 605 by a tubular outer housing 602.
 This arrangement suffers from the previously described shortcomings in that air strays away from the Coanda flow, particularly when the jet is spaced away from a surface.
 While it is conceivable that the performance of the invention of the Day publication would be improved by blowing air in the reverse direction, down the outer air return duct and back up through the central air delivery duct, stray air would then accumulate in the central area rather than be ejected out radially. Unfortunately, the spinning air from the air pump fan would cause the air from the nozzle to be thrown out radially due to centrifugal force (centripetal acceleration) and the system would not work. This effect could be overcome by the addition of flow straightening vanes following the fan. However, none are shown, and one may conclude that the effects of spiraling airflow were not understood by the designer.
 The Day publication has more complex systems with jets to accelerate airflow to pull it around the Coanda surface, and additional jets to blow air down to stir up dust and others to optimize airflow within the system. However, these additions are not pertinent to the analysis herein.
 The problems with the invention of the Day publication are remedied by the Applicant's toroidal vortex vacuum cleaner. The toroidal vortex vacuum cleaner is a bagless design and one in which airflow must be contained within itself at all times. The contained airflow continually circulates from the vacuum cleaner nozzle, to a centrifugal separator, and back to the nozzle. Since dust is not always fully separated, some dust will remain in the airstream heading back towards the nozzle. The air already within the system, however, does not leave the system preventing dust from escaping back into the atmosphere. It is not sufficient to design the cleaner to ensure essentially sealed operation while operating adjacent to a surface being cleaned, operation must also remain sealed when away from a surface to prevent fine dust particles from re-entering the surrounding air.
 Another reason for maintaining sealed operation when the apparatus is away from the surface is to prevent the vacuum cleaner nozzle from blowing surface dust around.
 The Day publication, in most of its configurations, is coaxial in that air is blown out from a central duct and is returned into a coaxial return duct. The toroidal vortex attractor is coaxial, but operates the in the opposite direction. With the toroidal vortex attractor, air is blown out of an annular duct and returned into a central duct.
 The inventor has also noted the presence of “cyclone” bagless vacuum cleaners in the prior art. The present invention utilizes an entirely different type of flow geometry allowing for much greater efficiency and lighter weight. Nonetheless, the following represent references that the inventor believes to be representative of the art in the field of bagless cyclone vacuum cleaners. One skilled in the art will plainly see that these do not approach the scope of the present invention, but they have been included for the sake of completeness.
 Dyson U.S. Pat. No. 4,593,429 discloses a vacuum cleaning appliance utilizing series connected cyclones. The appliance utilizes a high-efficiency cyclone in series with a low-efficiency cyclone. This is done in order to effectively collect both large and small particles. In conventional cyclone vacuum cleaners, large particles are carried by a high-efficiency cyclone, thereby reducing efficiency and increasing noise. Therefore, Dyson teaches incorporating a low-efficiency cyclone to handle the large particles. Small particles continue to be handled by the high-efficiency cyclone. While Dyson does utilize a bagless configuration, the type of flow geometry is entirely different. Furthermore, the energy required to sustain this flow is much greater than that of the present invention.
 Song, et al U.S. Pat. No. 6,195,835 is directed to a vacuum cleaner having a cyclone dust collecting device for separating and collecting dust and dirt of a comparatively large particle size. The dust and dirt is sucked into the cleaner by centrifugal force. The cyclone dust collecting device is biaxially placed against the extension pipe of the cleaner and includes a cyclone body having two tubes connected to the extension pipe and a dirt collecting tub connected to the cyclone body.
 Specifically, the dirt collecting tub is removable. The cyclone body has an air inlet and an air outlet. The dirt-containing air sucked via the suction opening enters via the air inlet in a slanting direction against the cyclone body, thereby producing a whirlpool air current inside of the cyclone body. The dirt contained in the air is separated from the air by centrifugal force and is collected at the dirt collecting tub. A dirt separating grill having a plurality of holes is formed at the air outlet of the cyclone body to prevent the dust from flowing backward via the air outlet together with the air. Thus, the dirt sucked in by the device is primarily collected by the cyclone dust connecting device, thus extending the period of time before replacing the paper filter.
 The device of Song et al. differs primarily from the present invention in that it requires a filter. The present invention utilizes such an efficient flow geometry that the need for a filter is eliminated. Furthermore, the conventional cyclone flow of Song et al is traditionally less energy efficient and noisier than the present invention.
 Thus, as stated above, there is a clear need for a light weight, efficient and quiet bagless vacuum cleaner.
 The present invention relies upon technology from the applicant's prior invention disclosed in co-pending application “Toroidal Vortex Bagless Vacuum Cleaner,” filed Apr. 13, 2001, which is herein incorporated by reference. The bagless vacuum cleaner of this invention was developed from technology disclosed in the co-pending application “Toroidal and Compound Vortex Attractor,” filed Apr. 9, 2001, which is incorporated herein by reference. These attractors stem from technology disclosed in the co-pending application “Lifting Platform,” Ser. No. 09/728,602, filed on Dec. 1, 2000, which is incorporated herein by reference. Finally, the lifting platform technology is based upon technology disclosed in co-pending application “Vortex Attractor,” Ser. No. 09/316,318, filed May 21, 1999, which is incorporated herein by reference.
 Described herein are embodiments that deal with both toroidal vortex vacuum cleaner nozzles and systems. The nozzles include simple concentric systems and more advanced, optimized systems. Such optimized systems utilize a thickened inner tube that is rounded off at the bottom for smooth airflow from the air delivery duct to the air return duct. It is also contemplated that the nozzle include flow straightening vanes to eliminate rotational components in the airflow that greatly harm efficiency. The cross section of the nozzle need not be circular, in fact, a rectangular embodiment is disclosed herein, and other embodiments are possible.
 The toroidal vortex nozzle is composed of concentric inner and outer tubes. Dust-laden airflow is contained in the inner tube, and cleaned airflow is contained between the outer and inner tubes. Also, straightening vanes are disposed between the inner and outer tubes. These straightening vanes provide non-rotating airflow back to the nozzle. If air is rotating, a significant amount can be expelled from the annulus into the atmosphere, thus compromising the efficiency of the nozzle.
 The preferred implementation of the present invention involves using the toroidal vortex nozzle with a vacuum cleaner. The nozzle takes in dust-laden air in through the inner tube, and delivers dust-free air back to the annulus between the inner and outer tubes. Dust-laden air is taken in through an inner tubing leading into the impeller blades. The blades accelerate incoming air into a circular pattern inducing the cylindrical vortex flow in a separation chamber. Alternatively, an axial pump or propeller can be mounted in the inner tube. The inner tube may be swelled out for this purpose. Inside the separation chamber, dirt and debris are centrifugally separated. The cleaned air is then driven into an annulus formed by the gap between the outer tube and the inner tube. Straightening vanes in the annulus manipulate airflow to eliminate rotational components. Straightened airflow is essential for a toroidal vortex nozzle to perform optimally. If air is rotating, a significant amount can be expelled from the annulus into the atmosphere, thus compromising the efficiency of the nozzle. However, the centrifugal separator is capable of cleaning air without a nozzle. The cylindrical vortex in the centrifugal separator is an inherent part of the dust separation process and is in itself independent of the toroidal vortex nozzle application.
 One of the main features of a vacuum cleaner system utilizing a toroidal vortex nozzle is the inherent low power consumption. The losses that must exist when bags or filters are utilized are eliminated. Bags and filters resist airflow, thus requiring greater power to maintain a proper flowrate. Additional efficiency arises from the closed air system. Energy supplied by the impeller is not lost because air is not expelled into the atmosphere, but is instead retained in the system. Finally, since only smooth changes in the direction of airflow are made, the effect on the energy of the moving air is minimal. Hence, the disclosed system contains efficiency provisions not considered by the prior art. Furthermore, the design is expected to be virtually maintenance free.
 It is an object of the present invention to provide toroidal vortex vacuum cleaner nozzles.
 Additionally, it is an object of the present invention to provide an efficient vacuum cleaner nozzle.
 Furthermore, it is an object of the present invention to provide a quiet vacuum cleaner nozzle.
 In addition, it is an object of the present invention to provide a low-maintenance vacuum cleaner nozzle.
 Also, it is an object of the present invention to facilitate an efficient, bagless vacuum cleaner.
 A further understanding of the present invention can be obtained by reference to a preferred embodiment set forth in the illustrations of the accompanying drawings. Although the illustrated embodiment is merely exemplary of systems for carrying out the present invention, both the organization and method of operation of the invention, in general, together with further objectives and advantages thereof, may be more easily understood by reference to the drawings and the following description. The drawings are not intended to limit the scope of this invention, which is set forth with particularity in the claims as appended or as subsequently amended, but merely to clarify and exemplify the invention.
 For a more complete understanding of the present invention, reference is now made to the following drawings in which:
FIG. 1, already discussed, depicts the establishment of the coanda effect (PRIOR ART);
FIG. 2, already discussed, depicts the dynamics of the coanda effect (PRIOR ART);
FIG. 3, already discussed, depicts the coanda effect on a spherical surface with both radial and tangential components of motion (PRIOR ART);
FIG. 4, already discussed, depicts a coanda vacuum cleaner nozzle (PRIOR ART);
FIG. 5, already discussed, depicts the undesirable airflow in a coanda vacuum cleaner nozzle (PRIOR ART);
FIG. 6, already discussed, depicts a side and bottom view of an annular coanda vacuum cleaner nozzle (PRIOR ART);
FIG. 7 depicts a toroidal vortex, shown sliced in half;
FIG. 8 graphically depicts the pressure distribution across the toroidal vortex of FIG. 7;
FIG. 9 depicts a toroidal vortex attractor;
FIG. 10 depicts a cross section of a concentric vacuum system;
FIG. 11 depicts a concentric vacuum system with air being sucked up the center and blown down the sides;
FIG. 12 depicts the dynamics of the re-entrant airflow of the system of FIG. 11;
FIG. 13 depicts a cross section of an exemplary toroidal vortex vacuum cleaner nozzle in accordance with the present invention;
FIG. 14 depicts a perspective view of an exemplary rectangular toroidal vortex vacuum cleaner nozzle in accordance with the present invention;
FIG. 15 depicts a cross section of an exemplary toroidal vortex bagless vacuum cleaner having an exemplary circular plan form;
FIG. 16 depicts a cross section in which the toroidal vortex nozzle creates a downward air plume;
FIGS. 17A and 17B depict venting techniques that prevent excessive pressure in the annular duct;
FIG. 18 depicts a cross section of a vortex nozzle functioning with venting;
FIGS. 19A and 19B depict an alternative embodiment of the vortex nozzle that prevents pluming and maintains a toroidal vortex against surfaces;
FIGS. 20A and 20B depict conventional vacuum cleaner nozzles (PRIOR ART); and
FIGS. 21A and 21B depict a toroidal vortex nozzle against a surface and a pile carpet.
 As required, a detailed illustrative embodiment of the present invention is disclosed herein. However, techniques, systems and operating structures in accordance with the present invention may be embodied in a wide variety of forms and modes, some of which may be quite different from those in the disclosed embodiment. Consequently, the specific structural and functional details disclosed herein are merely representative, yet in that regard, they are deemed to afford the best embodiment for purposes of disclosure and to provide a basis for the claims herein which define the scope of the present invention. The following presents a detailed description of a preferred embodiment (as well as some alternative embodiments) of the present invention.
 Certain terminology will be used in the following description for convenience in reference only and will not be limiting. The words “in” and “out” will refer to directions toward and away from, respectively, the geometric center of the device and designated and/or reference parts thereof. The words “up” and “down” will indicate directions relative to the horizontal and as depicted in the various figures. The words “clockwise” and “counterclockwise” will indicate rotation relative to a standard “right-handed” coordinate system. Such terminology will include the words above specifically mentioned, derivatives thereof and words of similar import.
 A toroidal vortex is a donut of rotating air. The most common example is a smoke ring. It is basically a self-sustaining natural phenomenon. FIG. 7 shows a toroidal vortex 700, at an angle, and sliced in two to illustrate the airflow 701. In a section of the vortex, a particular air motion section is shown by a stream tube 702, in which the air constantly circles around. Here it is shown with a mean radius 703 and mean speed 704. Circular motion is maintained by a pressure differential across the stream tube, the pressure being higher on the outside than the inside. This pressure difference Δp is, by momentum theory, Δp=
FIG. 8 shows a typical pressure profile across the toroidal vortex. Shown is the pressure on axis 801 as a function of distance in the x direction 802. Line 803 is a reference for atmospheric pressure, which remains constant along the x direction. The present invention was developed from a toroidal vortex attractor previously described by the inventor.
FIG. 9 shows a toroidal vortex attractor that has a motor 901 driving a centrifugal pump located within an outer housing 902. The centrifugal pump comprises blades 903 and backplate 904. This pumps air around an inner shroud 905 so that the airflow is a toroidal vortex with a solid donut core. Flow straightening vanes 906 are inserted after the centrifugal pump and between the inner shroud 905 and the outer casing 902 in order to remove the tangential component of air motion from the airflow. The air moves tangentially around the inner shroud 905 cross section, but radially with respect to the centrifugal pump.
 Air pressure within the housing 902 is below ambient. The pressure difference between ambient and inner air is maintained by the curved airflow around the inner shroud's 905 lower outer edge. The outer air turns the downward flow between the inner shroud 905 and outer casing 902 into a horizontal flow between the inner shroud and the attracted surface 907. This pressure difference is determined by
 The toroidal vortex attractor 900 can be thought of as a vacuum cleaner without a dust collection system. Dust particles picked up from the attracted surface 907 are picked up by the high speed low pressure airflow and circulate around.
 The toroidal vortex vacuum cleaner is a bagless design and one in which airflow must be contained within itself at all times. Air continually circulates from the area being cleaned, through the dust collector and back again. The contained airflow continually circulates from the vacuum cleaner nozzle, to a centrifugal separator, and back to the nozzle. Since dust is not always fully separated, some dust will remain in the airstream heading back towards the nozzle. The air already withing the system, however, does not leave the system preventing dust from escaping back into the atmosphere. It is not sufficient to design the cleaner to ensure essentially sealed operation while operating adjacent to a surface being cleaned, operation must also remain sealed when away from a surface to prevent fine dust particles from re-entering the surrounding air.
 Sealed operation away from a surface is also important because it prevents the vacuum cleaner nozzle from blowing surface is dust around.
 The toroidal vortex attractor is coaxial and operates in a way that air is blown out of an annular duct and returned into a central duct. FIG. 10 shows a system 1000 comprising outer tube 1001 and inner tube 1002 in which air passes down the inner tube 1003 and returns up the outer tube 1001. While it would be desirable that the outgoing air returns up into the air return duct 1005; a simple experiment shows that this is not so. Air from the central delivery duct 1004 forms a plume 1007 that continues on for a considerable distance before it disperses. Thus, air is sucked into the air return duct from the surrounding area 1006. This arrangement, without Coanda jet shaping is clearly unsuited to a sealed vacuum cleaner design.
FIG. 11 shows a system 1100 having the reverse airflow of FIG. 10. Again, system 1100 comprises outer tube 1101 and inner tube walls 1102 (which form inner tube 1103). Air is blown down the outer air delivery duct 1104 and returned up the central return duct 1105. Air is initially blown out in a tube conforming to the shape of the outer air delivery duct 1104. As this air originates in the inner tube 1103, replacement air must be pulled from the space inside the tube of outgoing air. This leads to a low pressure zone at A, within and below the air return duct 1105. Consequently air is pulled in at A from the outgoing air. Thus the air (whose flow is exemplified by arrows 1107) is forced to turn around on itself and enter the return duct 1105. Such action is not perfect and a certain amount of air escapes 1108 at the sides of the air delivery duct, and is replaced by the same small amount of air 1106 being drawn into the air return duct 1105.
 Air interchange is reduced from the automatic lowering of the air pressure within the concentric system. FIG. 12 shows air returning from the delivery duct 1104 into the return duct 1105 with radius of curvature (R) 1203 and the velocity at 1204. With airspeed V at 1204, the pressure difference between the ambient outer air and the inside is
 The simple concentric nozzle system shown in FIGS. 11 and 12 can be optimized into an effective toroidal vortex vacuum cleaner nozzle 1300 depicted in FIG. 13. The inner tube 1301 is thickened out and rounded off at the bottom (inner fairing 1306) for smooth airflow around from the air delivery duct 1302 to the air return duct 1303. The outer tube 1304 is extended a little way below the inner tube 1301 end and rounded inwards somewhat so that air from the delivery duct 1302 is not ejected directly downwards but tends towards the center. This minimizes the amount of air leaking sideways from the main flow. The nozzle has flow straightening vanes 1305 to eliminate any corkscrewing in the downward air motion in the air delivery duct 1302 that would throw air out sideways from the bottom of the outer tube 1304 due to centrifugal action. When compared to the coanda nozzles of the prior art, the vortex nozzle 1300 has less leakage and has a much wider opening for the high speed air flow to pick up dust.
 The vortex nozzle has so far been depicted as circular in cross section, but this is not at all necessary. FIG. 14 shows a rectangular nozzle 1400 in which the ends are terminated by bringing the inner fairings 1401 to butt against the outer tube 1402. Air is delivered via the delivery duct 1403 and returns via the return duct 1404. Flow straightening vanes are omitted for clarity, but are, of course, essential. An alternate system, not shown, is to carry the nozzle cross section of FIG. 13 around the ends, as there will be some air leakage around the flat ends.
FIG. 15 shows the addition of a centrifugal dirt separator, yielding a complete toroidal vortex vacuum cleaner 1500. Again, the ducting is created by an inner tube 1507 placed concentrically within outer tube 1508. Airflow through the outer air delivery duct 1502, the inner air return duct 1503 and the toroidal vortex nozzle 1506 (comprising flow straightening vanes 1504 and inner fairing 1505) are as described previously in FIGS. 12, 13 and 14. The air mover is a centrifugal air pump (as in the toroidal vortex attractor of FIG. 9) comprising motor 1509, backplate 1510 and blades 1511. Air leaving the centrifugal pump blades is spinning rapidly so that dust and dirt are thrown to the circular sidewall of the outer casing 1512. Air moves downward and inwards to follow the bottom of the dirt box 1501 so that dirt is precipitated there as well. The air then turns upwards over a dirt barrier 1513 and down the air delivery duct 1502. At this point, the air is clean except for fine particulates that fail to be deposited in the dirt box 1501. These particulates circulate through the system repeatedly until they are finally deposited out. The system operates below atmospheric pressure so that air laden with fine dust is constrained within the system and cannot escape into the surrounding atmosphere. After use, the dirt that has been collected in the dirt box 1501 can be emptied via the dirt removal door 1514.
FIG. 15 depicts a circular nozzle 1506, but the system works equally well with the rectangular nozzle of FIG. 14. Various nozzle shapes can be designed and will operate satisfactorily, providing that the basic cross section of FIG. 13 is used.
 There are instances wherein the pressure in the outer tube 1601 leading to the nozzle may be slightly greater than ambient. This can cause some air to stray from the toroidal vortex flow in the nozzle. As in FIG. 16, the strayed air streams can flow into each other from opposing directions. This results in a high pressure region A. The high pressure zone of air will tend to flow downward in an air plume 1604. The downward flowing air plume 1604 is highly undesirable. First of all, the air plume prevents dust and other matter from being sucked into the inner tube 1602 since the region A is no longer lower than atmospheric pressure. As shown, outer air 1603 is drawn by downward airflow such that it flows downward along with the plume 1604. The indicated airflow demonstrates that the nozzle is impaired from its ability to suck in objects under these conditions. Furthermore, the downward flow of plume 1604 may blow dust away, even at a distance from the nozzle, scattering the dust into the atmosphere.
 To remedy the problems associated with plumes, the outer tube 1602 may be vented in order to lower pressure. Two possible configurations of vents are depicted in FIGS. 17A and 17B. FIG. 17A shows an embodiment wherein the inner wall of the inner tube 1701 is thickened before the vent opening 1703. Airflow is capable of bending around the thickened outer tube 1702 and exiting into the atmosphere. The higher mass dust particles, which may remain in the airflow due to imperfect separation, are incapable of bending with the airflow quickly enough to exit the system. Thus, air may be allowed to exit the system, thereby lowering pressure, while still containing dust within the system.
 The second possible embodiment, depicted in FIG. 17B, utilizes a tapered outer tube 1702 after the vent 1703. Once again, airflow is capable of bending and exiting into the atmosphere. However, the higher mass dust particles are incapable of bending quickly enough to escape. Consequently, the dust flow collides with the tapered wall and continues through the inner tube 1701. This embodiment, as well as that depicted in FIG. 17A, reduces pressure while preventing dust from being released into the atmosphere.
 Although these are two possible configurations of vents to reduce the pressure, other vent designs are possible to accomplish the same objective. Furthermore, other means to reduce pressure in the outer tube may be made without departing from the principles of the inventions.
 Importantly, these vents permit small amounts of airflow to escape, therefore minimally compromising the efficiency of the vacuum cleaner system. Furthermore, the usage of these vents is not at all necessary in all situations. However, venting adapts the vacuum cleaner system to perform optimally in situations involving very fine dust particles. Additionally, the vents may be designed such that the size of the vent may be controlled. This allows the vacuum to be instantly modified for different situations in which different type of matter is to be vacuumed. Further, a protective screen which does not interrupt the toroidal vortex fluid flow may be implemented to prevent large objects from being sucked into the nozzle. The protective screen and/or the nozzle may be adapted to easily snap on and off or may be permanently attached to the nozzle. Thus, the nozzle may be quickly adapted to situations that require vacuuming only small particles.
FIG. 18 illustrates the fluid flow resulting from such venting outer tube 1802 and inner donut 1801. Some air from the atmosphere is sucked into the nozzle replacing the air escaping through the vents. Nevertheless, all previously mentioned, desirable characteristics of the toroidal vortex nozzle are preserved.
 Another preventative measure against pluming is to extend the outer tube 1901 inward with an additional sleeve 1903 as shown in FIG. 19B. The additional barrier created by the additional sleeve 1903 helps guide air around inner donut 1902 into a toroidal vortex. Further, the nozzle can be placed against a surface 1904 without impeding the toroidal vortex flow. FIG. 19A depicts airflow when the nozzle is placed against a surface without the additional sleeve. As shown, airflow is blocked. Thus the efficiency of the toroidal vortex nozzle is not lost.
FIGS. 20A and 20B show how conventional nozzles behave in close proximity to a floor 2004 or other surfaces. Air is drawn from the atmosphere and sucked into the nozzle 2001 carrying dust 2003 along with it. Flanges 2005 with wheels (not shown for clarity) may be included as in FIG. 20B to fix the nozzle's 2001 height. Since the effectiveness of a conventional vacuum cleaner is determined by the amount of air that can be moved, placing the nozzle 2001 too close to the floor 2004 compromises effectiveness by restricting airflow.
 The toroidal vortex nozzle can avoid this problem. The airflow through the nozzle is as shown in FIG. 21A. Airflow is not restricted from flowing around inner donut 2104 even though the nozzle's outer tube 2103 is pressed against the surface 2105. Further, the air does not need to be accelerated from a stationary state and kinetic energy does not escape the system. Moreover, air is not expelled into the atmosphere preventing the escape of unseparated dust. This also makes the use of inefficient filters unnecessary.
FIG. 21B shows the nozzle being used on a pile carpet 2107. The resultant airflow is virtually the same as described in FIG. 21A. Here, pile 2107 is sucked into the nozzle such that the airflow from the annular duct between inner donut 2104 and outer tube 2103 can pass through it and back into inner donut 2104. Dirt particles 2106 are then removed from the pile 2107. This leads to more effective cleaning of the carpet 2107. The toroidal vortex nozzle may make the use of a brush or other means to loosen dirt particles 2106 unnecessary.
FIG. 22 shows an embodiment of the toroidal vortex nozzle which has a handle 2201 and light 2202. The nozzle may also be angled as shown in order to reach difficult places. Furthermore, the nozzle opening can be fitted with a protective screen 2203. The protective screen 2203 inhibits unwanted objects from entering the nozzle without interrupting toroidal vortex airflow. The protective screen 2203 may also be made to be removable.
 Additional adjustments may be made to specialize the nozzle for specific situations. FIG. 23 exhibits some possiblities. The nozzle may have brush bristles at 2303 to sweep dust and dirt. A ring (such as a gasket) may also be placed at 2303 to allow the nozzle to seal to a surface. Finger-like projections may also extend from the outer tube at 2303 to distance it from the surface. However, air, dust, and dirt may still pass in between those fingers. The end of the nozzle 2303 may comprise felt, or another soft material, to prevent damage to delicate objects or surfaces. Also, wheels 2302 may be fitted to the nozzle to allow it to roll along a surface. Furthermore, vents in the nozzle may be controlled via a dial 2301 to adjust the size of the vents or turn them on and off. Other means to adjust the vents are possible. Although these are possible adaptations of the toroidal vortex nozzle, the nozzle is not limited to these adaptations. Various other embodiments may be utilized without departing from the spirit or teachings of the present invention.
 While the present invention has been described with reference to one or more preferred embodiments, which embodiments have been set forth in considerable detail for the purposes of making a complete disclosure of the invention, such embodiments are merely exemplary and are not intended to be limiting or represent an exhaustive enumeration of all aspects of the invention. The scope of the invention, therefore, shall be defined solely by the following claims. Further, it will be apparent to those of skill in the art that numerous changes may be made in such details without departing from the spirit and the principles of the invention.