Abstract:
An apparatus and method for transporting a flow of air and particulates through a vacuum cleaner. The apparatus can include a manifold with two inlet ports that collect two separate streams of the flow, combine the streams, and direct the combined flow toward a filter element through a single outlet port. The flow can expand within the manifold between the inlet ports and the outlet ports to decelerate the flow. The manifold can also include a storage receptacle for storing a belt used to drive a roller brush of the vacuum cleaner.

Description:
TECHNICAL FIELD 
     The present invention relates to methods and apparatuses for transporting a flow of air and particulates through a vacuum cleaner. 
     BACKGROUND OF THE INVENTION 
     Conventional upright vacuum cleaners are commonly used in both residential and commercial settings to remove dust, debris and other particulates from floor surfaces, such as carpeting, wood flooring, and linoleum. A typical conventional upright vacuum cleaner includes a wheel-mounted head which includes an intake nozzle positioned close to the floor, a handle that extends upwardly from the head so the user can move the vacuum cleaner along the floor while remaining in a standing or walking position, and a blower or fan. The blower takes in a flow of air and debris through the intake nozzle and directs the flow into a filter bag or receptacle which traps the debris while allowing the air to pass out of the vacuum cleaner. 
     One drawback with some conventional upright vacuum cleaners is that the flow path along which the flow of air and particulates travels may not be uniform and/or may contain flow disruptions or obstructions. Accordingly, the flow may accelerate and decelerate as it moves from the intake nozzle to the filter bag. As the flow decelerates, the particulates may precipitate from the flow and reduce the cleaning effectiveness of the vacuum cleaner and lead to blocking of the flow path. In addition, the flow disruptions and obstructions can reduce the overall energy of the flow and therefore reduce the capacity of a flow to keep the particulates entrained until the flow reaches the filter bag. 
     Another drawback with some conventional upright vacuum cleaners is that the blowers and flow path can be noisy. For example, one conventional type of blower includes rotating fan blades that take in axial flow arriving from the intake nozzle and direct the flow into a radially extending tube. As each fan blade passes the entrance opening of the tube, it generates noise which can be annoying to the user and to others who may be in the vicinity of the vacuum cleaner while it is in use. 
     Still another drawback with some conventional upright vacuum cleaners is that the filter bag may be inefficient. For example, some filter bags are constructed by folding over one end of an open tube of porous filter material to close the one end, and leaving an opening in the other end to receive the flow of air and particulates. Folding the end of the bag can pinch the end of the bag and reduce the flow area of the bag, potentially accelerating the flow through the bag. As the flow accelerates through the bag, the particulates entrained in the flow also accelerate and may strike the walls of the bag with increased velocity, potentially weakening or breaking the bag and causing the particulates to leak from the bag. 
     SUMMARY OF THE INVENTION 
     The invention relates to methods and apparatuses for transporting a flow of air and particulates through a vacuum cleaner. The apparatus can include a manifold that collects two portions of the flow through corresponding first and second inlet ports and combines the two portions. The manifold can further include an outlet port that directs the combined flow toward a filter element for separating at least some of the particulates from the flow. 
     In one embodiment, the manifold can include a receptacle for storing a belt used to drive a roller brush of the vacuum cleaner. In another embodiment, the manifold can be removably attached to a support, and can clamp a flange of the filter element against the support. The manifold can have an elliptical outlet port corresponding to an elliptical opening of the filter element. The manifold can further include passages between the inlet ports and the outlet port that expand the flow passing through the outlet port. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a front isometric view of a vacuum cleaner having an intake body, an airflow propulsion device, a filter and a filter housing in accordance with an embodiment of the invention. 
     FIG. 2 is an exploded isometric view of an embodiment of the intake body and the airflow propulsion device shown in FIG.  1 . 
     FIG. 3 is an exploded isometric view of the airflow propulsion device shown in FIG.  2 . 
     FIG. 4 is a front elevation view of a portion of the airflow propulsion device shown in FIG.  3 . 
     FIG. 5 is a cross-sectional side elevation view of the airflow propulsion device shown in FIG.  3 . 
     FIG. 6 is an exploded isometric view of an embodiment of the filter housing, filter and manifold shown in FIG.  1 . 
     FIG. 7 is a cross-sectional front elevation view of the filter housing and filter shown in FIG.  1 . 
     FIG. 8 is an exploded top isometric view of a manifold in accordance with another embodiment of the invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention is directed toward methods and apparatuses for moving a flow of air and particulates through a vacuum cleaner and separating the particulates from the air. The apparatus can include a manifold that collects two streams of the flow, combines the streams, and directs the combined stream into a filter element where the particulates are separated from the flow. Many specific details of certain embodiments of the invention are set forth in the following description and in FIGS. 1-8 to provide a thorough understanding of such embodiments. One skilled in the art, however, will understand that the present invention may have additional embodiments and that they may be practiced without several of the details described in the following description. 
     FIG. 1 is an isometric view of a vacuum cleaner  10  in accordance with an embodiment of the invention positioned to remove particulates from a floor surface  20 . The vacuum cleaner  10  can include a head or intake body  100  having an intake nozzle including an intake aperture  111  for receiving a flow of air and particulates from the floor surface  20 . An airflow propulsion device  200  draws the flow of air and particulates through the intake opening  111  and directs the flow through two conduits  30 . The conduits  30  conduct the flow to a manifold  50  that directs the flow into a filter element  80 . The air passes through porous walls of the filter element  80  and through a porous filter housing  70 , leaving the particulates in the filter element  80 . The vacuum cleaner  10  further includes an upwardly extending handle  45  and wheels  90  (shown as forward wheels  90   a  and rear wheels  90   b ) for controlling and moving the vacuum cleaner over the floor surface  20 . 
     FIG. 2 is an exploded isometric view of an embodiment of the intake body  100  shown in FIG.  1 . The intake body  100  includes a baseplate  110  and an inner cover  150  that are joined together around the airflow propulsion device  200 . An outer cover  130  attaches to the inner cover  150  from above to shroud and protect the inner cover  150  and the airflow propulsion device  200 . A skid plate  116  is attached to the lower surface of the baseplate  110  to protect the baseplate  110  from abrasive contact with the floor surface  20  (FIG.  1 ). Bumpers  115  are attached to the outer corners of the baseplate  110  to cushion inadvertent collisions between the intake body  100  and the walls around which the vacuum cleaner  10  (FIG. 1) is typically operated. 
     As shown in FIG. 2, the forward wheels  90   a  and the rear wheels  90   b  are positioned to at least partially elevate the baseplate  110  above the floor surface  20  (FIG.  1 ). In one aspect of this embodiment, the rear wheels  90   b  can have a larger diameter than the forward wheels  90   a . For example, the rear wheels  90   b  can have a diameter of between four inches and seven inches, and in one embodiment, a diameter of five inches. In a further aspect of this embodiment, the rear wheels  90   b  can extend rearwardly beyond the rear edge of the intake body  100 . An advantage of this arrangement is that it can allow the vacuum cleaner  10  to be more easily moved over stepped surfaces, such as staircases. For example, to move the vacuum cleaner  10  from a lower step to an upper step, a user can roll the vacuum cleaner backwards over the lower step until the rear wheels  90   b  engage the riser of the step. The user can then pull the vacuum cleaner  10  upwardly along the riser while the rear wheels  90   b  roll along the riser. Accordingly, the user can move the vacuum cleaner  10  between steps without scraping the intake body  100  against the steps. A further advantage is that the large rear wheels  90   b  can make it easier to move the vacuum cleaner  10  from one cleaning site to the next when the vacuum cleaner is tipped backward to roll on the rear wheels alone. 
     In yet a further aspect of this embodiment, the rear wheels  90   b  extend rearwardly of the intake body  100  by a distance at least as great as the thickness of a power cord  43  that couples the intake body  100  to the handle  45  (FIG.  1 ). Accordingly, the power cord  43  will not be pinched between the intake body  100  and the riser when the vacuum cleaner  10  is moved between steps. In an alternate embodiment, for example, where users move the vacuum cleaner  10  in a forward direction between steps, the forward wheels  90   a  can have an increased diameter and can extend beyond the forward edge of the intake body  100 . 
     The outer cover  130  can include intake vents  125   a  for ingesting cooling air to cool the airflow propulsion device  200 . The baseplate  110  can include exhaust vents  125   b  for exhausting the cooling air. Accordingly, cooling air can be drawn into the intake body  100  through the intake vents  125   a  (for example, with a cooling fan integral with the airflow propulsion device  200 ), past the propulsion device  200  and out through the exhaust vents  125   b . In one aspect of this embodiment, the exhaust vents  125   b  are positioned adjacent the rear wheels  90   b . Accordingly, the cooling air can diffuse over the surfaces of the rear wheels  90   b  as it leaves the intake body  100 , which can reduce the velocity of the cooling air and reduce the likelihood that the cooling air will stir up particulates on the floor surface  20 . 
     The intake aperture  111  has an elongated rectangular shape and extends across the forward portion of the baseplate  110 . A plurality of ribs  119  extend across the narrow dimension of the intake aperture  111  to structurally reinforce a leading edge  121  of the baseplate  110 . The skid plate  116  can also include ribs  120  that are aligned with the ribs  119 . Accordingly, the flow of air and particulates can be drawn up through the skid plate  116  and into the intake aperture  111 . In one embodiment, the intake aperture  111  can have a width of approximately 16 inches and in other embodiments, the intake aperture can have a width of approximately 20 inches. In still further embodiments, the intake aperture  111  can have other suitable dimensions depending on the particular uses to which the vacuum cleaner  10  is put. 
     An agitation device, such as a roller brush  140 , is positioned just above the intake aperture  111  to aid in moving dust, debris, and other particulates from the floor surface  20  and into the intake aperture  111 . Accordingly, the roller brush  140  can include an arrangement of bristles  143  that sweep the particulates into the intake aperture  111 . The roller brush  140  can be driven by a brush motor  142  via a flexible belt  141  or other mechanism. 
     In one embodiment, both the intake aperture  111  and the roller brush  140  are symmetric about a symmetry plane  122  (shown in FIG. 2 in dashed lines) that extends upwardly through the center of the intake body  100  and the vacuum cleaner  10 . An advantage of this configuration is that the intake body  100  can be more likely to entrain particulates uniformly across the width of the intake aperture  111  and less likely to leave some of the particulates behind. As will be discussed in greater detail below, other features of the vacuum cleaner  10  are also symmetric about the symmetry plane  122 . 
     The intake body  100  further includes a flow channel  112  positioned downstream of the intake aperture  11  and the roller brush  140 . The flow channel  112  includes a lower portion  112   a  positioned in the baseplate  110  and a corresponding upper portion  112   b  positioned in the inner cover  150 . When the inner cover  150  joins with the baseplate  110 , the upper and lower portions  112   b  and  112   a  join to form a smooth enclosed channel having a channel entrance  113  proximate to the intake aperture  111  and the roller brush  140 , and a channel exit  114  downstream of the channel entrance  113 . 
     In one embodiment, the flow channel  112  has an approximately constant flow area from the channel entrance  113  to the channel exit  114 . In one aspect of this embodiment, the flow area at the channel entrance  113  is approximately the same as the flow area of the intake aperture  111  and the walls of the flow channel  112  transition smoothly from the channel entrance  113  to the channel exit  114 . Accordingly, the speed of the flow through the intake aperture  111  and the flow channel  112  can remain approximately constant. 
     As shown in FIG. 2, the channel entrance  113  has a generally rectangular shape with a width of the entrance  113  being substantially greater than a height of the entrance  113 . The channel exit  114  has a generally circular shape to mate with an entrance aperture  231  of the airflow propulsion device  200 . The channel exit  114  is sealably connected to the airflow propulsion device  200  with a gasket  117  to prevent flow external to the flow channel  112  from leaking into the airflow propulsion device and reducing the efficiency of the device. 
     FIG. 3 is an exploded front isometric view of the airflow propulsion device  200  shown in FIGS. 1 and 2. In the embodiment shown in FIG. 3, the airflow propulsion device  200  includes a fan  210  housed between a forward housing  230  and a rear housing  260 . The fan  210  is rotatably driven about a fan axis  218  by a motor  250  attached to the rear housing  260 . 
     The forward housing  230  includes the entrance aperture  231  that receives the flow of air and particulates from the flow channel  112 . In one embodiment, the flow area of the entrance aperture  231  is approximately equal to the flow area of the flow channel  112  so that the flow passes unobstructed and at an approximately constant speed into the forward housing  230 . The forward housing  230  further includes two exit apertures  232  (shown as a left exit aperture  232   a  and a right exit aperture  232   b ) that direct the flow radially outwardly after the flow of air and particulates has passed through the fan  210 . The exit apertures  232  are defined by two wall portions  239 , shown as a forward wall portion  239   a  in the forward housing  230  and a rear wall portion  239   b  in the rear housing  260 . The forward and rear wall portions  239   a ,  239   b  together define the exit apertures  232  when the forward housing  230  is joined to the rear housing  260 . 
     In one embodiment, the forward housing  230  includes a plurality of flexible resilient clasps  233 , each having a clasp opening  234  that receives a corresponding tab  264  projecting outwardly from the rear housing  260 . In other embodiments, other devices can be used to secure the two housings  230 ,  260 . Housing gaskets  235  between the forward and rear housings  230 ,  260  seal the interface therebetween and prevent the flow from leaking from the housings as the flow passes through the fan  210 . 
     The fan  210  includes a central hub  211  and a fan disk  212  extending radially outwardly from the hub  211 . A plurality of spaced-apart vanes  213  are attached to the disk  212  and extend radially outwardly from the hub  211 . In one embodiment, the vanes  213  are concave and bulge outwardly in a clockwise direction. Accordingly, when the fan  210  is rotated clockwise as indicated by arrow  253 , the fan  210  draws the flow of air and particulates through the entrance aperture  231 , pressurizes or imparts momentum to the flow, and directs the flow outwardly through the exit apertures  232 . 
     Each vane  213  has an inner edge  214  near the hub  211  and an outer edge  215  spaced radially outwardly from the inner edge. Adjacent vanes  213  are spaced apart from each other to define a channel  216  extending radially therebetween. In one embodiment, the flow area of each channel  216  remains approximately constant throughout the length of the channel. For example, in one embodiment, the width W of each channel  216  increases in the radial direction, while the height H of each channel decreases in the radial direction from an inner height (measured along the inner edge  214  of each vane  213 ) to a smaller outer height (measured along the outer edge  215  of each vane). In a further aspect of this embodiment, the sum of the flow areas of each channel  216  is approximately equal to the flow area of the entrance aperture  231 . Accordingly, the flow area from the entrance aperture  231  through the channels  216  remains approximately constant and is matched to the flow area of the inlet aperture  111 , discussed above with reference to FIG.  2 . 
     The fan  210  is powered by the fan motor  250  to rotate in the clockwise direction indicated by arrow  253 . The fan motor  250  has a flange  255  attached to the rear housing  260  with bolts  254 . The fan motor  250  further includes a shaft  251  that extends through a shaft aperture  261  in the rear housing  260  to engage the fan  210 . A motor gasket  252  seals the interface between the rear housing  260  and the fan motor  250  to prevent the flow from escaping through the shaft aperture  261 . One end of the shaft  251  is threaded to receive a nut  256  for securing the fan  210  to the shaft. The other end of the shaft  251  extends away from the fan motor, so that it can be gripped while the nut  254  is tightened or loosened. 
     FIG. 4 is a front elevation view of the rear housing  260  and the fan  210  installed on the shaft  251 . As shown in FIG. 4, the rear housing  260  includes two circumferential channels  263 , each extending around approximately half the circumference of the fan  210 . In one embodiment, the flow area of each circumferential channel  263  increases in the rotation direction  253  of the fan  210 . Accordingly, as each successive vane  213  propels a portion of the flow into the circumferential channel  263 , the flow area of the circumferential channel increases to accommodate the increased flow. In a further aspect of this embodiment, the combined flow area of the two circumferential channels  263  (at the point where the channels empty into the exit apertures  232 ) is less than the total flow area through the channels  216 . Accordingly, the flow will tend to accelerate through the circumferential channels  263 . As will be discussed in greater detail below with reference to FIG. 2, accelerating the flow may be advantageous for propelling the flow through the exit apertures  232  and through the conduits  30  (FIG.  2 ). 
     In the embodiment shown in FIG. 4, the exit apertures  232  are positioned 180° apart from each other. In one aspect of this embodiment, the number of vanes  213  is selected to be an odd number, for example, nine. Accordingly, when the outer edge  215  of the rightmost vane  213   b  is approximately aligned with the center of the right exit aperture  232   b , the outer edge  215  of the leftmost vane  213   a  (closest to the left exit aperture  232   a ) is offset from the center of the left exit aperture. As a result, the peak noise created by the rightmost vane  213   b  as it passes the right exit aperture  232   b  does not occur simultaneously with the peak noise created by the leftmost vane  213   a  as the leftmost vane passes the left exit aperture  232   a . Accordingly, the average of the noise generated at both exit apertures  232  can remain approximately constant as the fan  210  rotates, which may be more desirable to those within earshot of the fan. 
     As discussed above, the number of vanes  213  can be selected to be an odd number when the exit apertures  232  are spaced 180° apart. In another embodiment, the exit apertures  232  can be positioned less than 180° apart and the number of vanes  213  can be selected to be an even number, so long as the vanes are arranged such that when the rightmost vane  213   b  is aligned with the right exit aperture  232   b , the vane closest to the left exit aperture  232   a  is not aligned with the left exit aperture. The effect of this arrangement can be the same as that discussed above (where the number of vanes  213  is selected to be an odd number), namely, to smooth out the distribution of noise generated at the exit apertures  232 . 
     FIG. 5 is a cross-sectional side elevation view of the airflow propulsion device  200  shown in FIG. 2 taken substantially along line  5 — 5  of FIG.  2 . As shown in FIG. 5, each vane  213  includes a projection  217  extending axially away from the fan motor  250  adjacent the inner edge  214  of the vane. In the embodiment shown in FIG. 5, the projection  217  can be rounded, and in other embodiments, the projection  217  can have other non-rounded shapes. In any case, the forward housing  230  includes a shroud portion  236  that receives the projections  217  as the fan  210  rotates relative to the forward housing. An inner surface  237  of the shroud portion  236  is positioned close to the projections  217  to reduce the amount of pressurized flow that might leak past the vanes  213  from the exit apertures  232 . For example, in one embodiment, the inner surface  237  can be spaced apart from the projection  217  by a distance in the range of approximately 0.1 inches to 0.2 inches, and preferably about 0.1 inches. An outer surface  238  of the shroud portion  236  can be rounded and shaped to guide the flow entering the entrance aperture  231  toward the inner edges  214  of the vanes  213 . An advantage of this feature is that it can improve the characteristics of the flow entering the fan  210  and accordingly increase the efficiency of the fan. Another advantage is that the flow may be less turbulent and/or less likely to be turbulent as it enters the fan  210 , and can accordingly reduce the noise produced by the fan  210 . 
     In one embodiment, the fan  210  is sized to rotate at a relative slow rate while producing a relatively high flow rate. For example, the fan  210  can rotate at a rate of 7,700 rpm to move the flow at a peak rate of 132 cubic feet per minute (cfm). As the flow rate decreases, the rotation rate increases. For example, if the intake aperture  111  (FIG. 2) is obstructed, the same fan  210  rotates at about 8,000 rpm with a flow rate of about 107 cfm and rotates at about 10,000 rpm with a flow rate of about  26  cfm. 
     In other embodiments, the fan  210  can be selected to have different flow rates at selected rotation speeds. For example, the fan  210  can be sized and shaped to rotate at rates of between about 6,500 rpm and about 9,000 rpm and can be sized and shaped to move the flow at a peak rate of between about 110 cfm and about 150 cfm. In any case, by rotating the fan  210  at relatively slow rates while maintaining a high flow rate of air through the airflow propulsion device  200 , the noise generated by the vacuum cleaner  10  can be reduced while maintaining a relatively high level of performance. 
     In a further aspect of this embodiment, the performance of the airflow propulsion device  200  (as measured by flow rate at a selected rotation speed) can be at least as high when the airflow propulsion device  200  is uninstalled as when the airflow propulsion device is installed in the vacuum cleaner  10  (FIG.  1 ). This effect can be obtained by smoothly contouring the walls of the intake aperture  111  (FIG. 2) and the flow channel  112  (FIG.  2 ). In one embodiment, the intake aperture  111  and the flow channel  112  are so effective at guiding the flow into the airflow propulsion device  200  that the performance of the device is higher when it is installed in the vacuum cleaner  10  than when it is uninstalled. 
     Returning now to FIG. 2, the flow exits the airflow propulsion device  200  through the exit apertures  232  in the form of two streams, each of which enters one of the conduits  30 . In other embodiments, the airflow propulsion device can include more than two apertures  232 , coupled to a corresponding number of conduits  30 . An advantage of having a plurality of conduits  30  is that if one conduit  30  becomes occluded, for example, with particles or other matter ingested through the intake aperture  111 , the remaining conduit(s)  30  can continue to transport the flow from the airflow propulsion device. Furthermore, if one of the two conduits  30  becomes occluded, the tone produced by the vacuum cleaner  10  (FIG. 1) can change more dramatically than would the tone of a single conduit vacuum cleaner having the single conduit partially occluded. Accordingly, the vacuum cleaner  10  can provide a more noticeable signal to the user that the flow path is obstructed or partially obstructed. 
     Each conduit  30  can include an elbow section  31  coupled at one end to the exit aperture  232  and coupled at the other end to an upwardly extending straight section  36 . As was described above with reference to FIG. 4, the combined flow area of the two exit apertures  232  is less than the flow area through the intake opening  111 . Accordingly, the flow can accelerate and gain sufficient speed to overcome gravitational forces while travelling upwardly from the elbow sections  31  through the straight sections  36 . In one aspect of this embodiment, the reduced flow area can remain approximately constant from the exit apertures  232  to the manifold  50  (FIG.  1 ). 
     In one embodiment, the radius of curvature of the flow path through the elbow section  31  is not less than about 0.29 inches. In a further aspect of this embodiment, the radius of curvature of the flow path is lower in the elbow section than anywhere else between the airflow propulsion device  200  and the filter element  80  (FIG.  1 ). In still a further aspect of this embodiment, the minimum radius of curvature along the entire flow path, including that portion of the flow path passing through the airflow propulsion device  200 , is not less than 0.29 inches. Accordingly, the flow is less likely to become highly turbulent than in vacuum cleaners having more sharply curved flow paths, and may therefore be more likely to keep the particulates entrained in the flow. 
     Each elbow section  31  is sealed to the corresponding exit aperture  232  with an elbow seal  95 . In one embodiment, the elbow sections  31  can rotate relative to the airflow propulsion device  200  while remaining sealed to the corresponding exit aperture  232 . Accordingly, users can rotate the conduits  30  and the handle  45  (FIG. 1) to a comfortable operating position. In one aspect of this embodiment, at least one of the elbow sections  31  can include a downwardly extending tab  34 . When the elbow section  31  is oriented generally vertically (as shown in FIG.  2 ), the tab  34  engages a tab stop  35  to lock the elbow section  31  in the vertical orientation. In one embodiment, the tab stop  35  can be formed from sheet metal, bent to form a slot for receiving the tab  34 . The tab stop  35  can extend rearwardly from the baseplate  110  so that when the user wishes to pivot the elbow sections  31  relative to the intake body  100 , the user can depress the tab stop  35  downwardly (for example, with the user&#39;s foot) to release the tab  34  and pivot the elbow sections  31 . 
     In one embodiment, each elbow seal  95  can include two rings  91 , shown as an inner ring  91 a attached to the airflow propulsion device  200  and an outer ring  91 b attached to the elbow section  31 . The rings  91  can include a compressible material, such as felt, and each inner ring  91   a  can have a surface  92  facing a corresponding surface  92  of the adjacent outer ring  91   b . The surfaces  92  can be coated with Mylar or another non-stick material that allows relative rotational motion between the elbow sections  31  and the airflow propulsion device  200  while maintaining the seal therebetween. In a further aspect of this embodiment, the non-stick material is seamless to reduce the likelihood for leaks between the rings  91 . In another embodiment, the elbow seal  95  can include a single ring  91  attached to at most one of the airflow propulsion device  200  or the elbow section  31 . In a further aspect of this embodiment, at least one surface of the ring  91  can be coated with the non-stick material to allow the ring to more easily rotate. 
     Each elbow section  31  can include a male flange  32  that fits within a corresponding female flange  240  of the airflow propulsion device  200 , with the seal  95  positioned between the flanges  32 ,  240 . Retaining cup portions  123 , shown as a lower retaining cup portion  123   a  in the base plate  110  and an upper retaining cup portion  123   b  in the inner cover  150 , receive the flanges  32 ,  240 . The cup portions  123  have spaced apart walls  124 , shown as an inner wall  124   a  that engages the female flange  240  and an outer wall  124   b  that engages the male flange  32 . The walls  124   a ,  124   b  are close enough to each other that the flanges  32 ,  240  are snugly and sealably engaged with each other, while still permitting relative rotational motion of the male flanges  32  relative to the female flanges  240 . 
     FIG. 6 is a front exploded isometric view of the conduits  30 , the filter housing  70 , the manifold  50  and the propulsion device  200  shown in FIG.  1 . Each of these components is arranged symmetrically about the symmetry plane  122 . Accordingly, in one embodiment, the entire flow path from the intake opening  111  (FIG. 2) through the manifold  50  is symmetric with respect to the symmetry plane  122 . Furthermore, each of the components along the flow path can have a smooth surface facing the flow path to reduce the likelihood for decreasing the momentum of the flow. 
     As shown in FIG. 6, the conduits  30  include the elbow sections  31  discussed above with reference to FIG. 2, coupled to the straight sections  36  which extend upwardly from the elbow sections  31 . In one embodiment, each straight section  36  is connected to the corresponding elbow section  31  with a threaded coupling  38 . Accordingly, the upper portions of the elbow sections  31  can include tapered external threads  37  and slots  40 . Each straight section  36  is inserted into the upper portion of the corresponding elbow section  31  until an O-ring  39  toward the lower end of the straight section is positioned below the slots  40  to seal against an inner wall of the elbow section  31 . The coupling  38  is then threaded onto the tapered threads  37  of the elbow section  31  so as to draw the upper portions of the elbow section  31  radially inward and clamp the elbow section around the straight section  36 . The couplings  38  can be loosened to separate the straight sections  36  from the elbow sections  31 , for example, to remove materials that might become caught on either section. 
     Each straight section  36  extends upwardly on opposite sides of the filter housing  70  from the corresponding elbow section  31  into the manifold  50 . Accordingly, the straight sections  36  can improve the rigidity and stability of the vacuum cleaner  10  (FIG. 1) and can protect the housing  70  from incidental contact with furniture or other structures during use. In the manifold  50 , the flows from each straight section  36  are combined and directed into the filter element  80 , and then through the filter housing  70 , as will be discussed in greater detail below. 
     The manifold  50  includes a lower portion  51  attached to an upper portion  52 . The lower portion  51  includes two inlet ports  53 , each sized to receive flow from a corresponding one of the straight sections  36 . A flow passage  54  extends from each inlet port  53  to a common outlet port  59 . As shown in FIG. 6, each flow passage  54  is bounded by an upward facing surface  55  of the lower portion  51 , and by a downward facing surface  56  of the upper portion  52 . The lower portion  51  can include a spare belt or belts  141   a  stored beneath the upward facing surface  55 . The spare belt(s)  141   a  can be used to replace the belt  141  (FIG. 2) that drives the roller brush  140  (FIG.  2 ). 
     In the embodiment shown in FIG. 6, the outlet port  59  has an elliptical shape elongated along a major axis, and the flow passages  54  couple to the outlet port  59  at opposite ends of the major axis. In other embodiments, the flow passages can couple to different portions of the outlet port  59 , as will be discussed in greater detail below with reference to FIG.  8 . In still further embodiments, the outlet port  59  can have a non-elliptical shape. 
     Each flow passage  54  turns through an angle of approximately 180° between a plane defined by the inlet ports  53  and a plane defined by the outlet port  59 . Each flow passage  54  also has a gradually increasing flow area such that the outlet port  59  has a flow area larger than the sum of the flow areas of the two inlet ports  53 . Accordingly, the flow passing through the flow passages  54  can gradually decelerate as it approaches the outlet port  59 . As a result, particulates can drop into the filter element  80  rather than being projected at high velocity into the filter element  80 . An advantage of this arrangement is that the particulates may be less likely to pierce or otherwise damage the filter element  80 . 
     As shown in FIG. 6, the outlet port  59  can be surrounded by a lip  58  that extends downwardly toward the filter element  80 . In one aspect of this embodiment, the lip  58  can extend into the filter element to seal the interface between the manifold  50  and the filter element  80 . As will be discussed in greater detail below, the filter element  80  can include a flexible portion that sealably engages the lip  58  to reduce the likelihood of leaks at the interface between the manifold  50  and the filter element  80 . 
     In one embodiment, the filter element  80  includes a generally tubular-shaped wall  81  having a rounded rectangular or partially ellipsoidal cross-sectional shape. The wall  81  can include a porous filter material, such as craft paper lined with a fine fiber fabric, or other suitable materials, so long as the porosity of the material is sufficient to allow air to pass therethrough while preventing particulates above a selected size from passing out of the filter element  80 . The wall  81  is elongated along an upwardly extending axis  85  and can have opposing portions that curve outwardly away from each other. In one embodiment, the wall  81  is attached to a flange  82  that can include a rigid or partially rigid material, such as cardboard and that extends outwardly from the wall  81 . The flange  82  has an opening  83  aligned with the outlet port  59  of the manifold  50 . In one embodiment, the opening  83  is lined with an elastomeric rim  84  that sealably engages the lip  58  projecting downwardly from the outlet port  59  of the manifold  50 . In one aspect of this embodiment, the flange  82  is formed from two layers of cardboard with an elastomeric layer in between, such that the elastomeric layer extends inwardly from the edges of the cardboard in the region of the outlet port  59  to form the elastomeric rim  84 . 
     In one embodiment, the lower end of the filter element  80  is sealed by pinching opposing sides of the wall  81  together. In another embodiment, the end of the filter element  80  is sealed by closing the opposing sides of the wall  81  over a mandrel (not shown) such that the cross-sectional shape of the filter element is generally constant from the flange  82  to a bottom  86  of the filter element  80 . An advantage of this arrangement is that the flow passing through the filter element  80  will be less likely to accelerate, which may in turn reduce the likelihood that the particles within the flow or at the bottom of the filter element  80  will be accelerated to such a velocity as to pierce the wall  81  or otherwise damage the filter element  80 . In this manner, lighter-weight particles may be drawn against the inner surface of the wall  81 , and heavier particles can fall to the bottom  86  of the filter element  80 . 
     As shown in FIG. 6, the filter element  80  is removably lowered into the filter housing  70  from above. In one embodiment, the filter housing  70  can include a tube having a wall  75  elongated along the axis  85 . The wall  75  can be formed from a porous material, such as a woven polyester fabric, connected to an upper support  71  and a lower support  72 . The upper support  71  can have a generally flat upwardly facing surface that receives the flange  82  of the filter element  80 . The forward facing surface of the wall  75  can include text and/or figures, for example, a company name, logo, or advertisement. The forward and rear portions of the wall  75  can curve outwardly away from each other to blend with intermediate opposing side walls adjacent the conduits  30 , and to correspond generally to the shape of the filter element  80 . 
     Each of the supports  71 ,  72  includes an upper portion  73   a  and a lower portion  73   b  fastened together with screws  74 . As is best seen in cross-section in FIG. 7, each upper portion  73   a  has a flange  78   a  that extends alongside a corresponding flange  78   b  of the lower portion  73   b , clamping an edge of the wall  75  of the filter housing  70  therebetween. In other embodiments, the supports  71 ,  72  can include other arrangements for supporting the housing  70 . The lower portion  73   b  of the lower support  72  has a closed lower surface  67  that forms the base of the filter housing  70 . The upper portion  73   a  of the lower support  72  and both the upper and lower portions of the upper support  71  have open upper surfaces that allow the filter housing  70  to extend upwardly therethrough, and allow the filter element  80  to drop downwardly into the filter housing. 
     Returning to FIG. 6, the upper and lower supports  71 ,  72  each have conduit apertures  77  sized to receive the straight sections  36 . In one embodiment, the conduit apertures  77  are surrounded by flexible projections  69  attached to the lower portions  73   b  of each support  71 ,  72 . The projections  69  clamp against the straight section  36  to restrict motion of the straight sections  36  relative to the supports  71 ,  72 . In a further aspect of this embodiment, the projections  69  of the upper support  71  have circumferential protrusions  68  that engage a corresponding groove  41  of the straight section  36  to prevent the straight section  36  from sliding axially relative to the upper support  71 . 
     The upper and lower supports  71 ,  72  also include handle apertures  76  that receive a shaft  47  of the handle  45 . The lowermost aperture  76 a has a ridge  79  that engages a slot  44  of the handle shaft  47  to prevent the shaft from rotating. The handle  45  includes a grip portion  48  which extends upwardly beyond the filter housing  70  where it can be grasped by the user for moving the vacuum cleaner  10  (FIG. 1) and/or for rotating the filter housing  70  and the conduits  30  relative to the airflow propulsion device  200 , as was discussed above with reference to FIG.  2 . The grip portion  48  can also include a switch  46  for activating the vacuum cleaner  10 . The switch  46  can be coupled with an electrical cord  49  to a suitable power outlet, and is also coupled to the fan motor  250  (FIG. 3) and the brush motor  42  (FIG. 2) with electrical leads (not shown). 
     The upper support  71  includes two gaskets  57  for sealing with the manifold  50 . In one embodiment, the manifold  50  is removably secured to the upper support  71  with a pair of clips  60 . Accordingly, the manifold  50  can be easily removed to access the filter element  80  and the spare belt or belts  141   a . In another embodiment, the manifold  50  can be secured to the upper support  71  with any suitable releasable latching mechanism, such as flexible, extendible bands  60   a  shown in hidden lines in FIG.  6 . 
     FIG. 8 is an exploded isometric view of a manifold  50   a  in accordance with another embodiment of the invention. The manifold  50   a  includes a lower portion  51   a  connected to an upper portion  52   a . The lower portion  51   a  has an outlet port  59  with an elliptical shape elongated along a major axis. Flow passages  54   a  couple to the outlet port  59  toward opposite ends of a minor axis that extends generally perpendicular to the major axis. The flow passages  54   a  are bounded by an upward facing surface  55   a  of the lower portion  5 la and by a downward facing surface  50   a  of the upper portion  52   a , in a manner generally similar to that discussed above with reference to FIG.  6 . 
     From the foregoing it will be appreciated that, although specific embodiments of the invention have been described herein for purposes of illustration, various modifications may be made without deviating from the spirit and scope of the invention. Accordingly, the invention is not limited except as by the appended claims.