BALANCED FLOW VACUUM CLEANER

Abstract: An apparatus and method for transporting a flow of air and particulates through a vacuum cleaner. In one embodiment, the apparatus includes an intake body having an intake opening configured to receive the flow of air into particulates. An airflow propulsion device is coupled to the intake opening to draw the flow through the intake opening and through a flow passage having an approximately constant flow area. The flow continues through one or more conduits from the propulsion device to a filter element housed in a filter housing where the particulates are separated from the flow of air.

Description: BALANCED FLOW VACUUM CLEANER 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. In one embodiment, the apparatus includes an intake body having an intake opening configured to be positioned proximate to a floor surface for receiving the flow of air and particulates. The vacuum cleaner can further include a filter housing configured to receive a filter for separating the particulates from the flow of air, and at least one conduit coupled between the intake body and the filter housing. An airflow propulsion device is coupled between the intake opening and the conduit to draw the flow of air and particulates through the intake opening and toward the filter housing. The intake opening, the propulsion device, and the conduit define a flow path for the flow of air and particulates and in one embodiment, the flow path has an approximately constant flow area from the intake opening to the propulsion device. In another embodiment, a radius of curvature of the flow path from the intake opening through the propulsion device has a radius of a curvature not less than approximately 0.29 inches to provide smooth flow along the flow path. In still another embodiment, the flow path is divided between two conduits, each extending from the intake body toward the filter housing. In one aspect of this embodiment, the combined flow area through the two conduits is less than the flow area through the intake opening. BRIEF DESCRIPTION OF THE DRAWINGS Figure 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. Figure 2 is an exploded isometric view of an embodiment of the intake body and the airflow propulsion device shown in Figure 1. Figure 3 is an exploded isometric view of the airflow propulsion device shown in Figure 2. Figure 4 is a front elevation view of a portion of the airflow propulsion device shown in Figure 3. Figure 5 is a cross-sectional side elevation view of the airflow propulsion device shown in Figure 3. Figure 6 is an exploded isometric view of an embodiment of the filter housing, filter and manifold shown in Figure 1. Figure 7 is a cross-sectional front elevation view of the filter housing and filter shown in Figure 1. Figure 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 into a vacuum cleaner and separating the particulates from the air. The apparatus can include an intake passage and an airflow propulsion device having an approximately constant flow area to reduce pressure losses to the flow. Many specific details of certain embodiments of the invention are set forth in the following description and in Figures 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. Figure 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 1 1 1 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 1 1 1 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 90a and rear wheels 90b) for controlling and moving the vacuum cleaner over the floor surface 20. Figure 2 is an exploded isometric view of an embodiment of the intake body 100 shown in Figure 1. The intake body 100 includes a baseplate 1 10 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 1 16 is attached to the lower surface of the baseplate 1 10 to protect the baseplate 1 10 from abrasive contact with the floor surface 20 (Figure 1). Bumpers 1 15 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 (Figure 1) is typically operated. As shown in Figure 2, the forward wheels 90a and the rear wheels 90b are positioned to at least partially elevate the baseplate 1 10 above the floor surface 20 (Figure 1). In one aspect of this embodiment, the rear wheels 90b can have a larger diameter than the forward wheels 90a. For example, the rear wheels 90b 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 90b 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 90b engage the riser of the step. The user can then pull the vacuum cleaner 10 upwardly along the riser while the rear wheels 90b 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 90b 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 rest on the rear wheels alone. In yet a further aspect of this embodiment, the rear wheels 90b 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 (Figure 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 90a 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 125a for ingesting cooling air to cool the airflow propulsion device 200. The baseplate 1 10 can include exhaust vents 125b for exhausting the cooling air. Accordingly, cooling air can be drawn into the intake body 100 through the intake vents 125a (for example, with a cooling fan coupled to the airflow propulsion device 100), past the propulsion device 200 and out through the exhaust vents 125b. In one aspect of this embodiment, the exhaust vents 125b are positioned adjacent the rear wheels 90b. Accordingly, the cooling air can diffuse over the surfaces of the rear wheels 90b 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 1 11 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 1 10. The skid plate 1 16 can also include ribs 120 that are aligned with the ribs 1 19. Accordingly, the flow of air and particulates can be drawn up through the skid plate 1 16 and into the intake aperture 1 11. In one embodiment, the intake aperture 1 1 1 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 1 1 1 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 1 1 1 to aid in moving dust, debris, and other particulates from the floor surface 20 and into the intake aperture 11 1. Accordingly, the roller brush 140 can include an arrangement of bristles 143 that sweep the particulates into the intake aperture 1 1 1. 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 1 11 and the roller brush 140 are symmetric about a symmetry plane 122 (shown in Figure 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 1 11 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 1 1 1 and the roller brush 140. The flow channel 1 12 includes a lower portion 112a positioned in the baseplate 110 and a corresponding upper portion 1 12b positioned in the inner cover 150. When the inner cover 150 joins with the baseplate 1 10, the upper and lower portions 112b and 1 12a join to form a smooth enclosed channel having a channel entrance 113 proximate to the intake aperture 11 1 and the roller brush 140. and a channel exit 1 14 downstream of the channel entrance 113. In one embodiment, the flow channel 1 12 has an approximately constant flow area from the channel entrance 1 13 to the channel exit 1 14. In one aspect of this embodiment, the flow area at the channel entrance 1 13 is approximately the same as the flow area of the intake aperture 1 1 1 and the walls of the flow channel 1 12 transition smoothly from the channel entrance 1 13 to the channel exit 1 14. Accordingly, the speed of the flow through the intake aperture 1 1 1 and the flow channel 1 12 can remain approximately constant. As shown in Figure 2. the channel entrance 1 13 has a generally rectangular shape with a width of the entrance 1 13 being substantially greater than a height of the entrance 1 13. The channel exit 1 14 has a generally circular shape to mate with an entrance aperture 231 of the airflow propulsion device 200. The channel exit 1 14 is sealably connected to the airflow propulsion device 200 with a gasket 1 17 to prevent flow external to the flow channel 1 12 from leaking into the airflow propulsion device and reducing the efficiency of the device. Figure 3 is an exploded front isometric view of the airflow propulsion device 200 shown in Figures 1 and 2. In the embodiment shown in Figure 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 1 12. In one embodiment, the flow area of the entrance aperture 231 is approximately equal to the flow area of the flow channel 1 12 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 232a and a right exit aperture 232b) 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 239a in the forward housing 230 and a rear wall portion 239b in the rear housing 260. The forward and rear wall portions 239a, 239b 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 21 1 and a fan disk 212 extending radially outwardly from the hub 21 1. A plurality of spaced-apart vanes 213 are attached to the disk 212 and extend radially outwardly from the hub 21 1. 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 21 1 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 Figure 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. Figure 4 is a front elevation view of the rear housing 260 and the fan 210 installed on the shaft 251. As shown in Figure 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 Figure 2, accelerating the flow may be advantageous for propelling the flow through the exit apertures 232 and through the conduits 30 (Figure 2). In the embodiment shown in Figure 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 213b is approximately aligned with the center of the right exit aperture 232b, the outer edge 215 of the leftmost vane 213a (closest to the left exit aperture 232a) is offset from the center of the left exit aperture. As a result, the peak noise created by the rightmost vane 213b as it passes the right exit aperture 232b does not occur simultaneously with the peak noise created by the leftmost vane 213a as the leftmost vane passes the left exit aperture 232a. 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 213b is aligned with the right exit aperture 232b. the vane closest to the left exit aperture 232a 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. Figure 5 is a cross-sectional side elevation view of the airflow propulsion device 200 shown in Figure 2 taken substantially along line 5-5 of Figure 2. As shown in Figure 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 Figure 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 1 1 1 (Figure 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 1 10 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 (Figure 1). This effect can be obtained by smoothly contouring the walls of the intake aperture 1 1 1 (Figure 2) and the flow channel 112 (Figure 2). In one embodiment, the intake aperture 1 1 1 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 Figure 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 1 1 1 , 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 (Figure 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 Figure 4. the combined flow area of the two exit apertures 232 is less than the flow area through the intake opening 1 1 1. 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 (Figure 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 (Figure 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 (Figure 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 Figure 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 1 10 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 ' 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 91b attached to the elbow section 31. The rings 91 can include a compressible material, such as felt, and each inner ring 91a can have a surface 92 facing a corresponding surface 92 of the adjacent outer ring 91b. 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 123a in the base plate 110 and an upper retaining cup portion 123b in the inner cover 150, receive the flanges 32, 240. The cup portions 123 have spaced apart walls 124, shown as an inner wall 124a that engages the female flange 240 and an outer wall 124b that engages the male flange 32. The walls 124a, 124b 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. Figure 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 Figure 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 1 1 1 (Figure 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 Figure 6, the conduits 30 include the elbow sections 31 discussed above with reference to Figure 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 (Figure 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 Figure 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 141a stored beneath the upward facing surface 55. The spare belt 141a can be used to replace the belt 141 (Figure 2) that drives the roller brush 140 (Figure 2). In the embodiment shown in Figure 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 Figure 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 Figure 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 porosi 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 Figure 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 i / 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 awa\ 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 73a and a lower portion 73b fastened together with screws 74. As is best seen in cross-section in Figure 7. each upper portion 73a has a flange 78a that extends alongside a corresponding flange 78b of the lower portion 73b. 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 73b of the lower support 72 has a closed lower surface 67 that forms the base of the filter housing 70. The upper portion 73a 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 Figure 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 73b 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 76a 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 (Figure 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 Figure 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 (Figure 3) and the brush motor 42 (Figure 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 141a. 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 60a shown in hidden lines in Figure 6. Figure 8 is an exploded isometric view of a manifold 50a in accordance with another embodiment of the invention. The manifold 50a includes a lower portion 51a connected to an upper portion 52a. The lower portion 51a has an outlet port 59 with an elliptical shape elongated along a major axis. Flow passages 54a couple to the outlet port 59 toward opposite ends of a minor axis that extends generally perpendicular to the major axis. The flow passages 54a are bounded by an upward facing surface 55a of the lower portion 51a and by a downward facing surface 50a of the upper portion 52a, in a manner generally similar to that discussed above with reference to Figure 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.

Claims: CLAIMS 1. A vacuum cleaner, comprising: an intake body having an intake opening configured to be positioned proximate to a floor surface for receiving a flow of air and particulates; a filter element for separating the particulates from the flow of air; at least one conduit coupled between the intake body and the filter element; and an airflow propulsion device coupled between the intake opening and the at least one conduit to draw the flow of air and particulates through the intake opening and toward the filter element, wherein the intake opening, the propulsion device and the conduit define a flow path for the flow of air and particulates and the flow path has an approximately constant flow area from the intake opening to the propulsion device. 2. The vacuum cleaner of claim 1 wherein the airflow propulsion device includes a rotatable fan coupled to an electric motor, the fan having a hub and a plurality of vanes extending radially outwardly from the hub, the hub and vanes being rotatable relative to the intake body to move the flow of air and particulates along the flow path. 3. The vacuum cleaner of claim 1 wherein the intake opening has an intake flow area and the conduit is a first conduit, further comprising a second conduit spaced apart from the first conduit, a combined flow area of the two conduits being less than the intake flow area. 4. The vacuum cleaner of claim 1 wherein the filter housing includes a manifold having a first opening coupled to the at least one conduit and a second opening configured to be in fluid communication with the filter, the manifold having a first flow area proximate to the first opening and a second flow area proximate to the second opening, the second opening being larger than the first opening to reduce a velocity of the airflow passing through the manifold. 5. The vacuum cleaner of claim 1 wherein the intake opening has a width of approximately 16 inches. 6. The vacuum cleaner of claim 1 wherein the intake opening has a width of approximately 20 inches. 7. The vacuum cleaner of claim 1 wherein walls of the flow passage are generally smooth. 8. The vacuum cleaner of claim 1 wherein a minimum curvature of the flow passage is equal to or greater than approximately 0.29 inches. 9. The vacuum cleaner of claim 1 wherein the at least one conduit has a generally upright portion with an approximately constant flow area that is less than the flow area at the intake opening. 10. The vacuum cleaner of claim 1 wherein the propulsion device has an entrance opening with a generally circular cross-sectional shape and the intake opening has a generally rectangular cross-sectional shape. 11. A vacuum cleaner, comprising: an intake body having an intake opening configured to be positioned proximate to a floor surface for receiving a flow of air and particulates from the floor surface; a filter element for separating the particulates from the flow of air; at least one conduit coupled between the intake body and the filter element; and an airflow propulsion device coupled between the intake opening and the at least one conduit housing, wherein the intake opening, the propulsion device and the conduit define a flow path, the flow path having an approximately constant flow area from the intake opening to the propulsion device, the flow path from the intake opening through the propulsion device having a radius of curvature not less than approximately 0.29 inches to provide smooth flow along the flow path. 12. The vacuum cleaner of claim 1 1 wherein the airflow propulsion device has an entrance opening for receiving the flow of air and particulates and an exit opening for exiting the flow of air and particulates. further wherein the flowpath changes direction by approximately 90° between the entrance opening and the exit opening. 13. The vacuum cleaner of claim 1 1 wherein the airflow propulsion device includes a rotatable fan coupled to an electric motor, the fan having a hub and a plurality of vanes depending from the hub. the hub and vanes being rotatable relative to the intake body to move the flow of air and particulates along the flow path. 14. The vacuum cleaner of claim 1 1, further comprising a manifold having a first opening coupled to the at least one conduit and a second opening configured to be in fluid communication with the filter, the manifold having a first flow area proximate to the first opening and a second flow area proximate to the second opening, the second flow being larger than the first opening to reduce a velocity of the airflow passing through the manifold. 15. The vacuum cleaner of claim 1 1 wherein walls of the flow passage are generally smooth. 16. The vacuum cleaner of claim 1 1 wherein the at least one conduit includes a generally horizontal portion, a generally vertical portion and a transition portion between the horizontal and vertical portions, the flow path through the transition portion having a minimum radius of curvature of approximately 0.29 inches. 17. A vacuum cleaner, comprising: an intake body having an intake opening for receiving a flow of air and particulates. the intake body further having at least two exit openings: a filter element to separate the particulates from the flow of air; at least two conduits, each having a first aperture coupled to one of the exit openings of the intake body and a second aperture in fluid communication with the filter element; and an airflow propulsion device coupled between the intake opening and the exit openings for moving the flow of air from the intake opening to the filter element. 18. The vacuum cleaner of claim 17 wherein the intake opening has an intake flow area and the conduits each have a conduit flow area, the sum of the conduit flow areas being less than the intake flow area to accelerate the flow through the conduits. 19. The vacuum cleaner of claim 17 wherein the conduits have generally smooth internal surfaces. 20. The vacuum cleaner of claim 17 wherein the conduits extend in generally straight parallel lines on opposite sides of the filter element. 21. The vacuum cleaner of claim 17 wherein a portion of each conduit extends outwardly from opposite sides of the intake body. 22. A vacuum cleaner, comprising: an intake body having an intake opening configured to be positioned proximate to a floor surface for receiving a flow of air and particulates; a filter element for separating the particulates from the flow of air; two conduits coupled between the intake body and the filter element: and an airflow propulsion device coupled between the intake opening and the conduits, wherein the intake opening, the propulsion device and the conduits define a flow path, the flow path being symmetric about a generally flat symmetry plane intersecting the intake opening and the propulsion device. 23. The vacuum cleaner of claim 22 wherein the symmetry plane extends between the conduits, the flow path including a first portion passing through one of the conduits and a second portion passing through the other conduit, the first and second portions being symmetric about the symmetry plane. 24. The vacuum cleaner of claim 22, further comprising a brush proximate to the intake opening, the brush having an arrangement of bristles that is symmetric about the symmetry plane. 25. The vacuum cleaner of claim 24 wherein the brush is rotatably mounted proximate to the intake opening and is rotatable relative to the intake opening. 26. The vacuum cleaner of claim 22, further comprising a manifold between the conduits and the filter housing, the manifold including a first portion coupled to the first conduit and a second portion coupled to the second conduit wherein the flow path extends through the first and second portions of the manifold symmetrically about the symmetry plane. 27. A vacuum cleaner, comprising: an intake body having an intake opening configured to be positioned proximate to a floor surface for receiving a flow of air and particulates, the intake body having a forward edge, a rear edge opposite the forward edge and a lower surface between the forward and rear edges; a filter element for separating the particulates from the flow of air: a flow channel coupled between the intake body and the filter element; and at least one wheel coupled to the intake body and projecting below at least a portion of the lower surface of the intake body to elevate the portion of the intake body above the floor surface, the wheel projecting forward of the forward edge or rearward of the rear edge by a selected distance. 28. The vacuum cleaner of claim 27, further comprising a power supply cord coupled to the intake body, the power supply cord having a thickness, the thickness being no larger than the selected distance by which the wheel projects forward of the forward edge or rearward of the rear edge. 29. The vacuum cleaner of claim 27 wherein the wheel is a first wheel positioned toward the rear edge of the intake body proximate one of a left side and a right side of the intake body, further comprising a second wheel positioned toward the rear edge of the intake body proximate the other of the left side and the right side of the intake body. 30. The vacuum cleaner of claim 27 wherein the wheel is a rear wheel positioned toward the rear edge of the intake body, further comprising at least one forward wheel positioned toward the forward edge of the intake body, the rear wheel having a diameter large than a diameter of the forward wheel. 31. A vacuum cleaner, comprising: an intake body having an intake opening configured to be positioned proximate to a floor surface for receiving a flow of air and particulates, the intake body having a lower surface proximate to the floor surface and a vent for exhausting cooling flow for cooling a component within the intake body; a filter element for separating the particulates from the flow of air; D a flow channel coupled between the intake body and the filter element: and at least one wheel coupled to the intake body and projecting belo at least a portion of the lower surface of the intake body to elevate the portion of the intake body above the floor surface, the wheel being positioned in a path of the cooling air passing outwardly through the vent to diffuse the cooling air. 32. The vacuum cleaner of claim 31 wherein the intake body has a forward edge and a rear edge opposite the forward edge, further wherein the wheel is a rear wheel positioned proximate the rear edge of the intake body. 33. The vacuum cleaner of claim 31 wherein the vent is an exhaust vent and the intake body has an intake vent spaced apart from the exhaust vent for receiving the cooling air. 34. A method for drawing a flow of air and particulates into a vacuum cleaner, comprising: drawing the flow of air and particulates through an intake opening of the vacuum cleaner, the intake opening having an intake flow area; passing the flow of air and particulates from the intake opening into an airflow propulsion device while maintaining a flow area occupied by the flow of air and particulates approximately equal to the intake flow area; passing the flow of air and particulates through the airflow propulsion device to a filter element; and separating at least a portion of the particulates from the flow of air at the filter element. 35. The method of claim 34 wherein passing the flow of air and particulates through the airflow propulsion device includes propelling the flow of air and particulates with a rotatable fan. 36. The method of claim 35 wherein the fan includes a plurality of spaced apart vanes having flow channels therebetween, further wherein passing the flow through the propulsion device includes maintaining a combined flow area through the flow channels approximately equal to the intake flow area. 37. The method of claim 34 wherein passing the flow of air and particulates to the filter element includes passing a first portion of the flow through a first conduit and passing a second portion of the flow through a second conduit spaced apart from the first conduit. 38. The method of claim 34 wherein passing the flow of air and particulates to the filter element includes passing the flow through a manifold and expanding the flow area occupied by the flow as the flow passes through the manifold. 39. The method of claim 34 wherein passing the flow of air and particulates to the filter element includes passing a first portion of the flow through a first generally vertical flow passage and passing a second portion of the flow through a second generally vertical flow passage while maintaining a combined flow area of the first and second vertical flow passages to be less than the intake flow area to accelerate the flow. 40. A method for drawing a flow of air and particulates into a vacuum cleaner, comprising: drawing the flow of air and particulates through an intake opening of the vacuum cleaner, the intake opening having a first flow area; passing the flow of air and particulates from the intake opening into an airflow propulsion device having a second flow area approximately equal to the first flow area, while passing the flow of air and particulates along a curved flow path having all radii of curvature in a direction of the flow greater than or equal to about 0.29 inches; passing the flow of air and particulates from the airflow propulsion device to a filter element; and separating at least a portion of the particulates from the flow of air at the filter element. 41. The method of claim 40 wherein passing the flow of air and particulates from the airflow propulsion device includes passing the flow to the filter element without passing the flow around a radius of less than about 0.29 inches. 42. The method of claim 40 wherein passing the flow of air and particulates from the airflow propulsion device includes passing a first portion of the flow through a first conduit extending from the airflow propulsion device toward the filter element and passing a second portion of the flow through a second conduit extending from the airflow propulsion device toward the filter element. 43. The method of claim 40 wherein passing the flow from the airflow propulsion device includes passing a first portion of the flow generally upward through a first conduit toward the filter element and passing a second portion of the flow generally upward through a second conduit spaced apart from the first conduit toward the filter element. 44. The method of claim 40 wherein passing the flow from the airflow propulsion device includes passing the flow through a third flow area less than the first and second flow areas to accelerate the flow. 45. A method for drawing a flow of air and particulates into a vacuum cleaner, comprising: drawing the flow of air and particulates through an intake opening; passing the flow of air and particulates from the intake opening into and through an airflow propulsion device; passing a first portion of the flow from the airflow propulsion device through a first conduit to a filter element: pass a second portion of the flow from the airflow propulsion device through a second conduit to the filter element; and separating at least a portion of the particulates from the flow of air at the filter element. 46. The method of claim 45 wherein passing the flow through the first and second conduits includes passing the first portion of the flow through a first conduit flow area that is less than half a flow area of the intake opening and passing the second portion of the flow through a second conduit flow area that is less than half a flow area of the intake opening. 47. The method of claim 45 wherein passing the first portion of the flow from the airflow propulsion device to the filter element includes directing the flow outwardly away from the propulsion device and turning the flow through an angle of approximately 90 degrees toward the filter element. 48. The method of claim 45, further comprising combining the first and second portions of the flow prior to separating at least a portion of the particulates from the flow. 49. A method for drawing a flow of air and particulates into a vacuum cleaner, comprising: drawing the flow of air and particulates through an intake opening such that the flow of air and particulates is approximately symmetric about a symmetry plane intersecting the intake opening; passing the flow of air and particulates from the intake opening into and through an airflow propulsion device with the flow of air and particulates remaining approximately symmetric about the symmetry plane; passing the flow of air and particulates from the airflow propulsion device to a filter element; and separating at least a portion of the particulates from the flow of air at the filter element. 50. The method of claim 49 wherein passing the flow of air and particulates from the airflow propulsion device includes passing a first portion of the flow through a first conduit toward the filter element and passing a second portion of the flow through a second conduit toward the filter element, the first and second portions of the flow remaining approximately symmetric about the symmetry plane. 51. The method of claim 49, further comprising combining the first and second portions of the flow upstream of the filter element. 52. The method of claim 49 wherein the airflow propulsion device includes a fan having a plurality of spaced apart vanes and passing the flow through the airflow propulsion device includes passing the flow through passages between the vanes. 53. A method for transporting a vacuum cleaner between a lower portion of a stepped surface and an upper portion of a stepped surface, the upper and lower portions being joined by a generally vertical intermediate portion, the vacuum cleaner having an intake body with an intake opening for receiving a flow of air and particulates. the method comprising: rolling the vacuum cleaner over one of the lower portion and the upper portion of the stepped surface until a wheel of the vacuum cleaner engages the intermediate portion of the stepped surface; and rolling the vacuum cleaner along the intermediate portion of the stepped surface to the other of the lower portion and the upper portion of the stepped surface without engaging the intake body with the intermediate portion of the stepped surface. 54. The method of claim 53 wherein the vacuum cleaner includes a power cord coupled to the intake body, further wherein rolling the vacuum cleaner along the intermediate portion of the stepped surface includes rolling the vacuum cleaner without clamping the power cord between the stepped surface and the intake body.

Inventors: EMBREE MICHAEL E, MCCAIN JAMES F, ROBERTS TERRANCE M, EMBREE, MICHAEL, E, MCCAIN, JAMES, F., ROBERTS, TERRANCE, M.
Applicants: ORECK HOLDINGS LLC, ORECK HOLDINGS, LLC
Application year: 2000
Main classification: A47L
IPC codes: A47L5, A47L9