Abstract:
An agitator assembly for a vacuum cleaner comprises a dowel assembly with recesses at its opposite ends defined by outwardly inclined walls. Each recess has inwardly facing radial vanes, and a shaft end for holding the inner ring of a bearing assembly. End caps extend over the ends of the dowel, and each has a collar for holding the outer ring of the bearing assembly and an outer longitudinal wall for providing a dust shield. The rotating vanes create an air barrier to preclude dust from moving towards each bearing assembly, and the inclined walls of each recess direct dust tossed outwardly by centrifugal force out of the agitator assembly. The end caps and the walls defining each recess further define a labyrinth seal to keep dust from traveling to each bearing assembly.

Description:
This application claims benefit of U.S. Provisional Application No. 60/360,409, filed Feb. 27, 2002. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to an agitator assembly for a vacuum cleaner, and in particular to an agitator assembly having apparatus for preventing dust from contaminating the bearings of the assembly. 
     2. Description of the Prior Art 
     Agitator assemblies or brush roll assemblies for use in vacuum cleaners are well known in the art. An agitator assembly generally includes a wooden dowel which is configured to be driven by a belt or a gear train, and has tufts of bristles and/or beater bar elements projecting radially from the surface of the dowel for beating against the surface of a carpet to loosen dirt from the fibers of the carpet. The agitator assembly rotates on bearings or bushings, and one of the problems with agitator assemblies used in vacuum cleaners is that dust tends to collect in and contaminate the bearings or bushings, detracting from the free rotation of the agitator assembly and leading to damage to the bearings. One of the means for protecting the bearings from dust is the use of a labyrinth thread seal to protect the bearings from dust, as is shown, for example, in U.S. Pat. No. 5,373,603. However, labyrinth seals are not entirely effective in use. It is also known to use dust shields for covering the end of the dowel to inhibit the path of the flow of dust into the bearing; however, such dust shields are also not entirely effective. Most agitator assemblies are made from wood and require both time to shape the dowel and the added step of balancing to achieve rotational stability. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide an agitator assembly, which is rotated in a vacuum cleaner on a set of bearings, with means for preventing dust from contaminating the bearing. 
     Another object of the invention is to provide an agitator assembly for a vacuum cleaner which expels dust, which dust may otherwise have gotten in or near the bearings. 
     Still another object of the invention is to provide an agitator assembly which is balanced when it is made and does not require any subsequent rotational balancing. 
     A yet further object of the invention is to provide an agitator assembly which can be produced efficiently and economically while yielding a device of high operational quality. 
     A further object of the invention is to provide an agitator assembly for a vacuum cleaner which employs the movement of air generated by the rotation of a dowel assembly to keep dust from impairing the operation of the bearing assembly used in the agitator assembly. 
     An additional object is to provide a system for reducing or preventing dust from contaminating the bearing assembly in the agitator assembly of a vacuum cleaner which requires a small number of parts. 
     Still another object of the invention is to provide an agitator assembly from which threads and other fibers can be easily removed once they have been wound on the brush roll of the agitator assembly as it rotates. 
     Other objects should be apparent from the description to follow and from the appended claims. 
     The foregoing objects are achieved according to the preferred embodiment of the invention. Accordingly, a vacuum cleaner agitator or brush roll assembly is provided having a central shaft or pin on which is mounted a belt drive pulley for receiving the drive belt from a vacuum cleaner. The agitator assembly incorporates a dowel from which tufts of bristles extend radially to loosen dirt from the carpet fibers. The dowel having the extending tufts is referred to as a brush roll. The central shaft of the agitator assembly extends along the longitudinal axis of the dowel and is rotated about the axis with the dowel by the belt from the vacuum cleaner. The dowel has an indented or recessed portion at each of its ends which are configured in a truncated fashion with inclined walls extending radially outwardly from the innermost end of the walls to the respective ends of the dowel. A set of radial vanes extend inwardly from the inclined walls towards the longitudinal axis. An end cap or cover in the form of a hub is fixed in the vacuum cleaner to which the agitator assembly is mounted and extends over each end of the dowel and has a collar extending into the recess for fixedly engaging the outer ring of the ball bearing assembly. The collar surrounds the ball bearing assembly and forms part of a labyrinth seal as well as defining part of an air passageway. The shaft fixedly engages the inner ring of the ball bearing assembly. The inner surface of the collar is cylindrical in format to engage the outer ring of the ball bearing assembly, while the outer surface of the collar is inclined to be generally parallel with the vanes of the dowel. The end cap has surfaces which are perpendicular to the longitudinal axis of the agitator assembly and extend across each end of the dowel and have an outer longitudinally-extending cylindrical portion which extends over the outer diameter of the dowel. The end caps and the recessed ends of the dowel with the radial vanes form a centrifugal dust shield as discussed below. 
     The dowel assembly has a drive member such as a pulley which is generally parallel to the outer cylindrical surface of the dowel and is configured to be driven by the belt of the vacuum cleaner. The location of the latter member can be varied according to the type of vacuum cleaner in which the agitator assembly is to be used. When the belt of the vacuum cleaner is rotating, it in turn rotates the pulley, the shaft and dowel, which in turn rotates the inner ring of the ball bearing assembly but the outer ring of the bearing assembly and the end cap are stationary relative to the dowel assembly. Therefore, the shaft rotates the inner ring of the ball bearing assembly at opposite ends of the agitator assembly. 
     During rotation, there are two occurrences relating to dust. First, the rotation of the dowel and the vanes produces turbulent air in the space between the vanes at the ends of the dowel and the end cap; and the turbulent air acts as a barrier to prevent dust from flowing between the end cap and the vanes of the dowel, to prevent the dust from contaminating the bearings. The second occurrence is that any dust, which is near the bearings or in the space between the end cap and the dowel, is thrown outwardly by centrifugal force, and the inclined ramp of the undercut portion of the dowel and the outer inclined portion of the collar of the end cap cooperate to cause the dust or dirt which is thrown outwardly by centrifugal force to be forced from the agitator assembly, and away the vacuum cleaner. Thus, the vanes establish an air barrier to the dust, and centrifugal force moves any dirt or dust outwardly along the path established by the recess in the dowel and the end cap. As a result, any damage that could be caused by the dust is avoided. 
     The dowel assembly according to the invention is made from plastic rather than from wood, and is so designed that it can be fabricated in a rotationally stable form. The production of the dowel is fast, accurate, and does not require the additional step of balancing the unit as was required in the prior art using wooden agitator assemblies. Cutting channels extend along the outer surface of the dowel to enable the cutting and removal of threads and other fibers wound thereon. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of an agitator assembly according to the invention. 
     FIG. 2 is a cross-sectional view of the agitator assembly shown in FIG. 1 taken through the longitudinal axis of the agitator. 
     FIG. 3 is an enlarged portion of one end portion of the agitator assembly shown in the preceding figures. 
     FIG. 4 shows the agitator assembly in exploded form. 
     FIG. 5 shows the drive shaft with the belt-drive pulley in perspective form. 
     FIG. 6 shows the end of the dowel in enlarged form. 
     FIG. 7 is an enlarged end view of the dowel. 
     FIG. 8 is an enlarged, perspective view of the inside of the end cap. 
     FIG. 9 is an enlarged, perspective view of the outside of the end cap. 
     FIG. 10 is a perspective view of the ball bearing assembly. 
     FIG. 11 is a perspective view of a dowel in simplified form with a modified surface. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Turning first to FIG. 1, an agitator assembly  1  according to the preferred embodiment of the invention is shown. Agitator assembly  1  includes a dowel  3 , to which is fixedly secured a belt-drive pulley  5  for enabling the agitator assembly to be rotated by the drive belt from a vacuum cleaner in which the agitator assembly  1  is mounted. Agitator assembly  1  further includes an end cap  7  which serves as a dust shield and bearing holder assembly, one of which being disposed at each end of dowel  3 . Means are provided on the vacuum cleaner for fixedly securing the end cap  7  to the vacuum cleaner, so that the dowel is rotatable relative to the end cap and the outer ring of the bearing assembly fixed therein as described below. Drive pulley  5  could be disposed anywhere along dowel  3  according to the nature of the vacuum cleaner in which the agitator is to be installed. Drive pulley  5  could of course be replaced by other mechanical or electrical means depending on the drive apparatus of the vacuum cleaner. The surface of the pulley could be of any shape according to the type of belt or other drive mechanism. Tufts  9  of bristles extend outwardly from pockets in dowel  3  in a predetermined manner in order to dislodge dirt from carpets and other surfaces over which the agitator assembly is rotated by means of the vacuum cleaner in which it is installed. Tufts  9  could be held in dowel  3  by various means, such as by staples, bar anchors or fused in place. 
     FIGS. 2 and 3 show the agitator assembly in greater detail. Dowel  3  is cylindrical in form, and is preferably made by injection molding. Dowel  3  could have other shapes, and could be made using other manufacturing techniques. Also, other materials such as wood or metal could be used and still incorporate the concepts of the present invention. As will be explained in further detail below, injection molding gives fast, uniform results and yields a product of even density which does not require rotational balancing. Rotational balancing is required in order for the agitator to continue to operate smoothly, uniformly and freely in response to the rotation of the belt drive of the vacuum cleaner. Belt-drive pulley  5  is produced separately, and is included during the injection molding of dowel  3  in a properly designed die. Belt-drive pulley  5  is also preferably made from plastic in an injection-molding machine. Various pulley designs to accommodate various drive belts, such as crowned, V-groove, lugs and the like, could be used in different vacuum cleaners with other types of belt drive systems. Appropriate plastics for the pulley include nylon, glass-filled nylon, ABS and the like. Metal pulleys may also be appropriate. Extending through dowel  3  is a drive shaft  11  to which dowel  3  and pulley  5  are fixed, so that the latter two members rotate as shaft  11  rotates. Shaft  11  is cylindrical in shape and is slightly tapered at its ends, as shown in FIG. 5 to be described below. 
     Referring to FIGS. 1-4 and  7 , agitator assembly  1  is indented or recessed as shown in indentation, recess or depression  13  at its opposite ends and has an inclined side wall  15  defining the side of the depression. Side wall  15  is inclined inwardly starting from the end of dowel  3  and proceeding towards the interior of the dowel, or being inclined outwardly if one considers the depression beginning inside the dowel and extending towards the end of the dowel. The interior end of depression  13  is in part defined by a flat end wall  17  so that depression  13  is in general a truncated cone. Extending radially inwardly from wall  15  is a series of uniformly spaced multiple vanes  19  whose purpose is described below. As explained later with respect to FIG. 7, there are eight vanes  19  in agitator assembly  1 . Inclined wall  15  is at the base of vanes  19 . 
     There are ball bearing assemblies  21  at opposite ends of dowel  3  which engage on their interior surfaces the end portions  23  of drive shaft  11 . This is shown most clearly in FIG.  3 . Each ball bearing assembly  21  includes an inner ring or race  22  with an inner diameter generally equal to the outer diameter of shaft  11  so that ring  22  will rotate with shaft  11 , an outer ring or race  24  with an outer diameter, and a set of ball bearings  26 . Inner ring  22  rests on shoulder  28  of dowel  3 . The ball bearing assembly is also shown in FIG.  10 . As explained in further detail below, shaft  11 , with dowel  3  and belt-drive pulley  5 , rotates with respect to outer ring  24  of ball bearing assembly  21 . It is very important to keep dust from contaminating ball bearing assembly  21 , since otherwise shaft  11  and dowel  3  could not freely and uniformly rotate. In order to help assist in keeping dust from ball bearing assembly  21 , an end cap  7  is provided. Referring to FIGS. 3,  8  and  9 , end cap  7  includes a generally flat end portion  25  having an inwardly directed, generally cylindrical end wall or collar  27  (“inwardly” means towards dowel  3 ). Collar  27  has an interior bore generally equal to the outer diameter of the outer ring  24  which fixedly engages the outside surface  29  of ball bearing assembly  21 . This can be accomplished during manufacture by a press-fit. Collar  27  extends inwardly beyond ball bearing assembly  21  into a pocket defined by an axial wall  31  and an inclined wall  33 , which pocket terminates at wall  17  of dowel  3 . The outside of collar  27  is inclined by the same amount as vanes  19 , but collar  27  terminates in the radial direction prior to its entering into the space between vanes  19 . Also extending inwardly from end cap  7  is an outer or exterior cylindrical wall  35  which is spaced radially from the end of dowel  3  as shown. End cap  7  is fixedly retained in the vacuum cleaner in which agitator assembly  1  is mounted. This is accomplished according to the end cap holding apparatus in the vacuum cleaner. An outside edge  36  or an edge of a protrusion  37  (discussed below) could be fixedly held by the vacuum cleaner to keep outer ring  24  fixed with respect to dowel  3  as the latter rotates. The combination of the shaft, the dowel, the outwardly extending tufts, the bearing assemblies and the end caps is referred to as the agitator assembly. 
     The outside of end cap  7 , shown in FIG. 9, includes a square protrusion  37  having an inside recess  39  into which the end portion of shaft  23  extends. The end cap could be of any shape to accommodate being mounted in various housings specific to different customer designs. 
     As referred to herein, the term dowel assembly, referred to by numeral  40 , includes dowel  3 , pulley  5  and tufts  9 . The ball bearing assembly can be considered part of dowel assembly  21  or end cap  7 , since inner ring  22  is fixed on shaft  11  and outer ring  24  is fixed in end cap  7 . 
     Disposed on dowel  3  is a first series of cutting channels  41  extending around the middle of dowel  3  and another set of cutting channels  43  extending around the end portions of dowel  3 . These can be seen most clearly in FIGS. 1-4 and  6 . As dowel assembly  40  rotates, it oftentimes picks up thread, yarn and other fibers, and they wind around dowel  3  and are difficult to simply grab onto and pull off; yet they must be removed in order to properly clean the vacuum cleaner and to keep the agitator assembly running freely and uniformly. Cutting channels  41  and  43  enable the user of a vacuum cleaner to insert scissors or some other cutting device into one of the channels  41  and into one of the channels  43  at both ends of agitator assembly  1  to cut the thread, yarn or other fiber, to enable it to be easily pulled from dowel  3 . Cutting channels  41  and  43  could be grooves, such as radial grooves or slots, protruded surfaces or mounds, or a combination of grooves and protrusions. Different grooving arrangements covering the length of the dowel to avoid interfering with specific tuft patterns may be used. 
     Another device for use in removing threads and other flexible articles wound about a rotational dowel is shown in FIG.  11 . FIG. 11 shows a dowel assembly  70  of the same type as dowel assembly  10 , but with all of the details omitted for sake of clarity except for a pair of cutting arrangements  74  extending along a dowel  72 . Each cutting arrangement  74  includes a channel  76  shown extending longitudinally along the surface of dowel  72 , and a parallel and adjacent protrusion  78 . The combination of the channel  76  and protrusion  78  exposes free portions of threads and other flexible articles wound about dowel  72 , which can be easily cut by running a scissor blade, a knife blade or other cutting instrument along one of channels  76  or adjacent protrusion  78 . Once cut, the material can be removed and discarded. Many variations are possible. Only one pair of a channel and a protrusion can be used. While the channel and protrusion are shown running in the longitudinal direction, they could follow a curved path, be provided in segments along dowel  72 , or have other patterns. Either one or more channels, or one or more protrusions, could be used alone, spread apart from each other, or be used with other surface variations in dowel  72 . 
     Belt-drive assembly  5  will now be described in greater detail. With reference to FIGS. 3 and 5, pulley  5  has a generally cylindrical exterior portion having a pair of parallel, cylindrical rails  45 , which are generally V-shaped in configuration, having a wide base, and each terminating in a pointed apex  47 . Disposed on the outermost portion of pulley  5  is a pair of cylindrical end portions  49  which terminate at the beginning of guide rails  45 . A series of upwardly extending, V-shaped guides  51 , which are concentric with guide rails  45  about the longitudinal axis of pulley  5  (which is coaxial with the axis of shaft  11  when mounted thereon), are provided for being engaged by the drive belt from the vacuum cleaner. The generally cylindrical portion of pulley  5  terminates at an interior cylindrical surface  53 , and from which extend inwardly multiple radial support members or spokes  55  which terminate at a hub  56  having an inner diameter  57  which is about the same as the outer diameter of shaft  11 . Four spokes  55  are shown. Of course, other numbers of spokes  55  could be used as well. During the assembly of agitator assembly  1 , pulley  5  is press-fit on shaft  11  to hold it in place, as shown, for example, in FIG.  5 . 
     As noted above, shaft  11  is cylindrical in form having tapered ends shown at  59  in FIG.  3 . Shaft  11  is preferably made from an appropriate steel or aluminum member. 
     With further reference to dowel  3 , an annular indented portion  61  is shown in FIGS. 4 and 6. This portion has longitudinal slots  63  having at their midpoint transverse, radial slots  65 . These are the recesses in which the spokes from pulley  5  extend, the pulley having been removed to enable a clear explanation of the embodiment. 
     As noted above, the opposite ends of dowel  3  have a set of inclined vanes  19 . These vanes cooperate with collar  27  of dust shield and bearing assembly holder  7  to provide a very important purpose of the present invention. 
     Turning again to FIG. 3, a belt from a vacuum cleaner engages belt-drive pulley  5  to rotate dowel assembly  40  which comprises shaft  11 , dowel  3  and pulley  5 . Vanes  19  rotate about cylindrical collar  27  and outer ring  24  of bearing assembly  21  at both ends of the agitator assembly. This rotation causes air turbulence to occur in a cavity  66  which runs from the inner edge of bearing assembly  21 , around the inner portion of collar  27  to its termination at the inside edge of end cap  7 . This turbulence provides a barrier to dust which otherwise could flow through the cavity and contaminate bearing assembly  21 . Moreover, any dust which happened to be in or around bearing assembly  21  would be thrown outwardly by centrifugal force. Centrifugal force would cause the dust to move parallel to the inclined surface  15  to the gap between the respective ends of dowel  3  and the inner surface of dust cap and bearing assembly holder  7 . The dust would then be forced around the outer wall  35  and away from bearing assembly  21 . 
     The invention thus provides an extremely efficient agitator assembly which can be made using normal manufacturing techniques, particularly with injection molding. An extremely effective yet economical provision is made for protecting the bearings from dust contamination. The parts can be made faster than with the former wooden dowels, would not require the rotational balancing which had been required for wood dowels, enables the uniform and fast assembly of the tuft bristles, and belt-drive pulley as discussed above. Since the parts are made from plastic, they can be made in a variety of colors to render the unit attractive as well. The plastic should be hard and durable, and types of polypropylene should be appropriate. 
     Even though injection molded plastic has been found very useful for components of the preferred embodiment of the invention described above, in some instances wood, metal, glass or plastic other than injection-molded plastic might prove preferable while still incorporating the present invention. A beater bar could be made in a molding process as an integral part of the molded dowel if desired. The surface of the dowel could be smooth or textured. Moreover, the inventive concepts described herein could be used on wetback cleaning machines, such as steam cleaners, shampooers and wet vacuum cleaners. 
     The invention has been described in detail, with particular emphasis on the preferred embodiment thereof, but variations and modifications may occur to those skilled in the art to which the invention pertains.