Patent Publication Number: US-11641989-B2

Title: Brushroll for vacuum cleaner

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation of U.S. patent application Ser. No. 16/021,693, filed Jun. 28, 2018, now U.S. Pat. No. 10,799,081, issued Oct. 13, 2020, which is a continuation of U.S. patent application Ser. No. 15/249,529, filed Aug. 29, 2016, now U.S. Pat. No. 10,034,588, issued Jul. 31, 2018, which is a division of U.S. patent application Ser. No. 14/208,381, filed Mar. 13, 2014, now U.S. Pat. No. 9,693,663, issued Jul. 4, 2017, which claims the benefit of U.S. Provisional Application No. 61/793,471, filed Mar. 15, 2013, all of which are incorporated herein by reference in their entirety. 
    
    
     BACKGROUND 
     Vacuum cleaners can include an agitator for agitating debris on a surface to be cleaned so that the debris is more easily ingested into the vacuum cleaner. In some cases, the agitator includes a motor-driven brushroll that rotates within a base or floor nozzle. Brushrolls typically have a generally cylindrical dowel with multiple bristle tufts extending radially from the dowel. 
     BRIEF SUMMARY 
     According to one aspect, the present disclosure relates to a brushroll having a brush dowel defining a rotational axis, the brush dowel defining a length and the brush dowel including an outer circumference that is non-cylindrical along at least a portion of the length, a set of first bristles protruding from the brush dowel, the set of first bristles forming a first chevron pattern, and a set of second bristles protruding from the brush dowel, the set of second bristles spaced from the set of first bristles and the set of second bristles forming a second chevron pattern 
     According to another aspect, the present disclosure relates to a brushroll having a brush dowel defining a rotational axis and an outer surface with multiple sets of bristles protruding from the brush dowel and spaced about the outer surface, the multiple sets of bristles including at least two differing bristles that define separate rows, and each of the separate rows forming a chevron pattern on the brush dowel. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings: 
         FIG.  1    is a perspective view of a vacuum cleaner. 
         FIG.  2    is a perspective view of a lower portion of the vacuum cleaner from  FIG.  1   , with portions cut away for clarity. 
         FIG.  3    is a perspective view of a brushroll according to an aspect of the present disclosure. 
         FIG.  4    is a close-up view of section IV of the brushroll from  FIG.  3   . 
         FIG.  5    is a close-up cross-sectional view of the brushroll taken through line V-V of  FIG.  3   . 
         FIG.  6    is a cross-sectional view of a dowel of the brushroll taken through line V-V of  FIG.  3   . 
         FIGS.  7 - 9    are schematic illustrations of an injection molding process which can be used to produce the dowel of  FIG.  6   . 
         FIG.  10    is a perspective view of a brushroll according to an aspect of the present disclosure. 
         FIG.  11    is a cross-sectional view through line XI-XI of  FIG.  10   . 
         FIG.  12    is a close-up cross-sectional view similar to  FIG.  5    of a brushroll according to an aspect of the present disclosure. 
         FIG.  13    is a close-up cross-sectional view similar to  FIG.  5    of a brushroll according to an aspect of the present disclosure. 
         FIG.  14    is a perspective view of a brushroll according to an aspect of the present disclosure. 
         FIG.  15    is a close-up view of section XV of the brushroll from  FIG.  14   . 
         FIG.  16    is a cross-sectional view through line XVI-XVI of  FIG.  14   . 
         FIG.  17    is a perspective view of a brushroll according to an aspect of the present disclosure. 
         FIG.  18    is a cross-sectional view through the brushroll of  FIG.  17   . 
         FIG.  19    is a perspective view of a brushroll according to an aspect of the present disclosure. 
         FIG.  20    is a close-up view of section XX of the brushroll from  FIG.  19   . 
         FIG.  21    is a cross-sectional view through line XXI-XXI of  FIG.  19   . 
         FIG.  22    is a perspective view of a brushroll according to an aspect of the present disclosure. 
         FIG.  23    is a cross-sectional view through the brushroll of  FIG.  22   . 
         FIG.  24    is a perspective view of a brushroll according to an aspect of the present disclosure. 
         FIG.  25    is a plan view of a dowel of the brushroll from  FIG.  24   . 
         FIG.  26    is a partially exploded view of the brushroll from  FIG.  24   . 
         FIG.  27    is a cross-sectional view through line XXVII-XXVII of  FIG.  24   . 
         FIG.  28    is a perspective view of a brushroll according to an aspect of the present disclosure. 
         FIG.  29    is a perspective view of a brushroll according to an aspect of the present disclosure. 
         FIG.  30    is a perspective view of a brushroll according to an aspect of the present disclosure. 
         FIGS.  31  and  32    are schematic views of a bristle tufting tool according to an aspect of the present disclosure. 
         FIGS.  33 - 37    are schematic views illustrating the steps of a method of tufting a brushroll dowel using the tufting tool of  FIGS.  31 - 32   . 
     
    
    
     DETAILED DESCRIPTION 
     The present disclosure relates to vacuum cleaners and in particular to vacuum cleaners having a motor-driven brushroll. For purposes of description related to the figures, the terms “upper,” “lower,” “right,” “left,” “rear,” “front,” “vertical,” “horizontal,” and derivatives thereof shall relate to the present disclosure as oriented in  FIG.  1    from the perspective of a user behind the vacuum cleaner, which defines the rear of the vacuum cleaner. However, it is to be understood that the present disclosure may assume various alternative orientations, except where expressly specified to the contrary. 
       FIG.  1    is a perspective view of the vacuum cleaner  10  in the form of an upright vacuum cleaner. While shown and referred to herein as an upright vacuum cleaner, the vacuum cleaner  10  can alternatively be configured as a hand-held vacuum cleaning device, or as an apparatus having a floor nozzle or a hand-held accessory tool connected to a canister or other portable device by a vacuum hose. Additionally, the vacuum cleaner  10  can be configured to have fluid distribution capability and/or extraction capability. 
     As illustrated, the vacuum cleaner  10  includes an upper housing  12  pivotally mounted to a lower base  14 . The upper housing  12  generally includes a main support section  16  supporting a collection system  18  for separating and collecting contaminants from a working airstream for later disposal. In one conventional arrangement illustrated herein, the collection system  18  can include a cyclone separator  20  for separating contaminants from a working airstream and a removable dirt cup  22  for receiving and collecting the separated contaminants from the cyclone separator  20 . The cyclone separator  20  can have a single cyclonic separation stage, or multiple stages. In another conventional arrangement, the collection system  18  can include an integrally formed cyclone separator and dirt cup, with the dirt cup being provided with a bottom-opening dirt door for contaminant disposal. It is understood that other types of collection systems  18  can be used, such as centrifugal separators or bulk separators. In yet another conventional arrangement, the collection system  18  can include a filter bag. The vacuum cleaner  10  can also be provided with one or more additional filters upstream or downstream of the collection system  18 . 
     The upper housing  12  is pivotally mounted to the base  14  for movement between an upright storage position, shown in  FIG.  1   , and a reclined use position (not shown). The vacuum cleaner  10  can be provided with a detent mechanism, such as a pedal  24  pivotally mounted to the base  14 , for selectively releasing the upper housing  12  from the storage position to the use position. The details of such a detent pedal  24  are known in the art, and will not be discussed in further detail herein. 
     The upper housing  12  also has an elongated handle  26  extending upwardly from the main support section  16  that is provided with a hand grip  28  at one end that can be used for maneuvering the vacuum cleaner  10  over a surface to be cleaned. A motor cavity  30  is formed at a lower end of the support section  16  and contains a conventional suction source such as a motor/fan assembly  36  ( FIG.  2   ) positioned therein in fluid communication with the collection system  18 . The vacuum cleaner  10  can also be provided with one or more additional filters upstream or downstream of motor/fan assembly. 
       FIG.  2    is a view of a lower portion of the vacuum cleaner  10  from  FIG.  1   , with portions cut away to show features of the base  14 . The base  14  can include an upper housing  32  that couples with a lower housing  34  to create a partially enclosed space therebetween. An agitator chamber  38  can be provided at a forward portion of the lower housing  34  for receiving a brushroll  40 . A suction nozzle opening  42  is formed in the lower housing  34  and is in fluid communication with the agitator chamber  38  and the collection system  18  ( FIG.  1   ). Wheels  44  can be provided on the base  14  for maneuvering the vacuum cleaner  10  over a surface to be cleaned. 
     The brushroll  40  is positioned within the agitator chamber  38  for rotational movement about an axis X. A single brushroll  40  is illustrated; however, it is within the scope of the present disclosure for dual rotating brushrolls to be used. Moreover, it is within the scope of the present disclosure for the brushroll  40  to be mounted within the agitator chamber  38  in a fixed or floating vertical position relative to the chamber  38  and lower housing  34 . 
     The brushroll  40  can be operably coupled to and driven by the motor/fan assembly  36  in the motor cavity  30 . The motor/fan assembly  36  can include a motor shaft  46  which is oriented substantially parallel to the surface to be cleaned and protrudes from the motor cavity  30  into a rear portion of the base  14 . A drive belt  48  operably connects the motor shaft  46  to the brushroll  40  for transmitting rotational motion of the motor shaft  46  to the brushroll  40 . Alternatively, a separate, dedicated agitator drive motor (not shown) can be provided within the base  14  to drive the brushroll  40 . 
     The base  14  can further include an optional suction nozzle height adjustment mechanism for adjusting the height of the suction nozzle opening  42  with respect to the surface to be cleaned. A rotatable knob  54  for actuating the adjustment mechanism can be provided on the exterior of the base  14 . In another variation, the suction nozzle height adjustment mechanism can be eliminated. 
     In operation, the vacuum cleaner  10  draws in debris-laden air through the base  14  and into the collection system  18  where the debris is substantially separated from the working air flow, which is generated by the motor/fan assembly  36 . The spinning motor shaft  46  of the motor/fan assembly  36  rotates the brushroll  40  via the drive belt  48  that is operably connected therebetween. Alternatively, a separate, dedicated agitator drive motor can rotate the brushroll  40 . As the brushroll  40  rotates, the bristles sweep across the surface to be cleaned to release and propel debris into the working air flow generated by the motor/fan assembly  36 , which carries the debris into the collection system  18 . The working air flow then passes through the motor cavity  30  and past the motor/fan assembly  36  prior to being exhausted from the vacuum cleaner  10 . The collection system  18  can be periodically emptied of debris. 
       FIG.  3    is a perspective view of a brushroll  40  according to a first example of the present disclosure. The brushroll  40  can be used with the vacuum cleaner  10  of  FIG.  1 - 2   , as described above. The brushroll  40  includes a generally cylindrical brush dowel  56  that is mounted on an elongated shaft  58  that extends through the center of the dowel  56  and defines the axis X around which the brushroll  40  rotates. A bearing  60  is mounted on both ends of the shaft  58  and in operation the dowel  56  rotates about the shaft  58  on the bearings  60 . A belt engagement surface  62  around the circumference of the dowel  56  near one end communicates with the belt  44  ( FIG.  2   ) and may include a pulley. The brushroll  40  is adapted to be rotationally driven in the direction indicated by arrow A. 
     A plurality of bristle ridges  64  project or extend from the exterior surface of the brush dowel  56 . A plurality of bristle tufts  66  project or extend from each bristle ridge  64 . Each bristle tuft  66  can include a plurality of flexible bristles, which may be made from a durable polymer material such as nylon or polyester, for example. Using the bristle ridges  64  to mount the bristle tufts  66  minimizes the amount of material needed for the dowel  56  by locally increasing the diameter of the dowel  56  where the bristle tufts  66  are attached, rather than increase the entire diameter of the dowel  56 . 
     At least one bristle stiffener  68  projects or extends from each bristle ridge  64 . The bristle stiffeners  68  are generally laterally coextensive with the bristle tufts  66 , and can extend generally along the entire length of the bristle ridges  64 . The bristle stiffeners  68  are positioned adjacent to a rear side of the bristle tufts  66 , with “rear” in this case being defined in relation of the direction of rotation A, such that upon the bristle tufts  66  engaging a surface to be cleaned, the bristle tufts  66  are prevented from bending over too far by the bristle stiffeners  68 . Overall, the bristle stiffeners  68  tend to keep the bristle tufts  66  more or less erect as they pass over the surface to be cleaned. The bristle stiffeners  68  are substantially rigid, and do not flex as the brushroll  40  rotates. Due to the presence of the bristle stiffeners  68 , the bristle tufts  66  can be softer, which reduces the amount of power needed to rotate the brushroll  40 . The bristle tufts  66  are less stiff than the bristle stiffeners  68 , can flex somewhat as the brushroll  40  rotates, although the presence bristle stiffeners  68  prevents at least some of the flexure that that bristle tufts  66  would otherwise experience without the bristle stiffeners  68 . 
     The bristle ridges  64  can be divided into two opposing rows extending along the dowel  56 , with each row having multiple bristle ridges  64 . The spacing between adjacent bristle ridges  64  can allow the rotating brushroll  40  to clear ribs on the lower housing  34  that prevent carpet from getting drawn into the suction nozzle opening  42  ( FIG.  1   ). The tufts  66  of one bristle ridge  64  are arranged in a generally helix pattern in single row spirally around the outer circumference of the brush dowel  56 . The angle at which the bristle tufts  66  are oriented can vary, but is illustrated as covering about 90 degrees per segment, which allows the dowel  56  to be moldable. 
     Spools  70  are formed at the ends of the dowel  56 , adjacent to the bearings  60 , for preventing hair and other debris from migrating along the dowel  56  towards the bearings  60 . At least a portion of the bristle ridges  64 , tufts  66 , and stiffeners  68  at the ends of the dowel  56  can extend onto the spools  70 . 
       FIG.  4    is a close-up view of a portion of the brushroll  40  from  FIG.  3   . Each bristle ridge  64  has a leading surface  72  and a trailing surface  74 , as defined by the direction of rotation, which project from the exterior surface of the brush dowel  56  and are joined by two end surfaces  76 ,  78  and an upper surface  80 . The bristle stiffener  68  can be integrally formed with the bristle ridge  64 , and can include an inner stiffener surface  82  which extends upwardly from the upper surface  80  to a stiffener edge  84  which joins the upper end of the trailing surface  74 . The height of the leading and trailing surfaces  72 ,  74  can be substantially constant along the length of the surfaces  72 ,  74 , but the trailing surface  74  can extend above the leading surface  72  to form the bristle stiffener  68 . The stiffener edge  84  is positioned below the radial end of the bristle tufts  68 . 
     The leading surface  72  and the trailing surface  74  can be non-planar, with a longitudinal twist formed in the leading surface  72  and the trailing surface  74 , such that the second end surface  78  is radially offset from the first end surface  76 . During rotation, bristle tufts  66  near the first end surface  76  will contact the surface to be cleaned first, with the bristle tufts  66  closer to the second end surface  78  sequentially following. The stiffener edge  84  braces the bristle tufts  66  to keep the bristle tufts  66  more or less erect as they pass over the surface to be cleaned 
       FIG.  5    is a close-up cross-sectional view of the brushroll  40  taken through line  5 - 5  of  FIG.  3   . Bristle holes  86  can be formed in the upper surface  80  and extend at least partially into the bristle ridge  64 . The bristle tufts  66  can be assembled to the dowel  56  by pressing bristles into the bristle holes  86  and securing the bristles using a fastener, such as a staple  88 . 
     The bristle stiffener  68  can be adjacent to the bristle holes  86 , such that there is a small gap G between the inner stiffener surface  82  and the closest portion of the bristle tuft  66 . In one example, the gap G can be approximately 0.5 mm. During manufacturing, it is difficult to place the bristle tuft  66  close to the bristle stiffener  68  because the bristles are guided by a sleeve during tufting. By removing a portion of the tufting sleeve to clear the bristle stiffener  68 , the bristle stiffener  68  itself can act as a guide to the tuft insertion on that the stiffener side. This allows the bristle tuft  66  to be located very close to the bristle stiffener  68 . 
       FIG.  6    is a cross-sectional view of the dowel  56  taken through line V-V of  FIG.  3   . The dowel  56 , including the bristle stiffeners  68 , can be integrally molded in one-piece using a two-plate mold. In the example shown, the bristle ridges  64  and bristle stiffeners  68  are tapered with an appropriate draft angle in the direction that the mold opens or the line of draw so that the dowel  56  can be released from the mold without additional actions or moving components such as slides or lifters, which are usually necessary for releasing die-locked or undercut part features from a mold. The draft angle can be defined as the angle formed between an interior mold wall and a vertical axis or plane. Typically, a draft angle of less than or equal to 90 degrees relative to vertical, which can also be referred to as a positive draft angle, is necessary to release a part feature from a two-plate mold. Conversely, a draft angle of greater than 90 degrees relative to vertical, which can be referred to as a negative draft angle, defines an undercut feature, which cannot be released from a two plate mold without additional actions or moving components in the mold. Conceptually, the dowel  56  can be divided into four quadrants I-IV, with a Y-axis and a Z-axis extending perpendicularly through the dowel  56  to define the four quadrants I-IV which proceeds in order in a counterclockwise direction around the dowel  56 . The Y-axis and Z-axis meet at an origin defined by the rotational axis X around which the brushroll  40  rotates (see  FIG.  3   ). 
     By confining the bristle stiffeners  68  to opposing quadrants of the dowel  56 , undercuts on the dowel  56  can be eliminated, such that a two-part mold having a single line of draw, which may be defined along the Z axis, can be used to produce the dowel  56  without requiring the use of a movable slide or lifter in the mold, which can simplify the mold design and can reduce mold cost. In the illustrated example, the bristle stiffeners  68  are in quadrants II and IV. The holes  86  for the bristle tufts  66  can be integrally formed in the dowel  56  during the molding process, or can be drilled into the dowel after molding. 
     The dowel  56  of the brushroll  40  shown in  FIG.  3 - 6    can be injection molded in accordance with the following method, illustrated in  FIG.  7 - 9   . The sequence of steps discussed is for illustrative purposes only and is not meant to limit the method in any way as it is understood that the steps may proceed in a different logical order, additional or intervening steps may be included, or described steps may be divided into multiple steps, without detracting from the present disclosure. For  FIGS.  7 - 9   , it is noted that the parting line of the mold, which is the plane in which the two mold halves meet, is not linear, but extends along the length of the dowel  56  following the bristle stiffeners  68  most of the length of the dowel. In this example, since the bristle stiffeners  68  wrap helically around the dowel  56  and are radially spaced from the rotational axis X of the dowel  56  (see  FIG.  3   ), the parting line is likewise radially spaced from the rotational axis X of the dowel  56  and will be substantially helical, changing contour with the bristle stiffeners  68  and extending along the stiffener edge  84  of the bristle stiffeners  68 . Thus, a parting line may show up as a raised line extending along the stiffener edge  84  of the bristle stiffeners  68  as a result of the molding, although a raised line is not necessarily always present. However, at any location along the dowel  56 , the bristle stiffeners  68  are located in opposing quadrants as described with respect to  FIG.  6   . Other contours for the parting line are also possible in which the parting line is non-parallel to the rotational axis X. Here, a helical parting line is used; in other examples, an angled parting line is used. 
       FIG.  7    shows a two-plate mold having two mold halves which together define a cavity configured for producing the dowel of the brushroll, with the mold closed and ready for injection. A shot of melt material is injected under pressure into the cavity, as depicted in  FIG.  8   . The melt material can include a polymeric material, such as polypropylene, ABS, or styrene. When the material is cooled and solidified, the mold is opened and the dowel part is ejected and removed, as shown in  FIG.  9   . The two mold halves can separate from the molded dowel  56 , allowing the molded dowel  56  to be ejected without obstruction from undercuts on the dowel  56 . It should be noted that the injection molding process described herein is simplified, and other steps common to injection molding, such as heating the raw material prior to injection and/or applying packing pressure, may also be performed. Furthermore, additional finishing steps such as attaching the bristle tufts  66 , inserting the shaft  58  and assembling the bearing holders  60  can also be performed to produce the brushroll  40 . 
       FIG.  10    is a perspective view of a brushroll  40  according to a second example of the present disclosure, in which like elements are identified with the same reference numerals. The brushroll  40  can be used in place of the brushroll  40  on the vacuum cleaner  10  shown in  FIGS.  1 - 2   , and can be substantially similar to the brushroll  40  shown the first example of  FIG.  3   , save for the orientation of the rows of bristle tufts  66  and the provision of additional rows of bristles. 
     In the example shown, the bristle tufts  66  (and likewise the bristle ridges  64  and bristle stiffeners  68 ) can have a repeating chevron pattern, where bristle tufts  66  on adjacent bristle ridges  64  meet at angles, such that the first end surface  76  of one bristle ridge  64  is radially aligned with the second end surface  78  of the adjacent bristle ridge  64  but is radially offset from the first end surface  76  of the same adjacent bristle ridge  64 . 
     A plurality of bristle ridges  90  can project or extend from the exterior surface of the brush dowel  56  and are arranged in two opposing rows extending along the dowel  56  between the opposing rows of bristle ridges  64 . The bristle ridges  90  can be substantially identical to the bristle ridges  64 , with the exception that they are not provided with bristle stiffeners  68 . A plurality of bristle tufts  92  project or extend from each bristle ridge  90 , and can be substantially identical to the bristle tufts  66 . The bristle tufts  92  (and likewise the bristle ridges  90 ) can have a repeating chevron pattern which generally follows the chevron pattern of the intervening rows of bristle tufts  66 . Circumferential gaps  94  extend around the dowel  56  and separate adjacent bristle ridges  64 ,  90  and allow the rotating brushroll  40  to clear ribs on the lower housing  34  that prevent carpet from getting drawn into the suction nozzle opening  42  ( FIG.  1   ). 
       FIG.  11    is a cross-sectional view through line  11 - 11  of  FIG.  10   . Bristle holes  96  can be formed in the upper surface of the bristle ridges  90  and receive the bristle tufts  92 . The individual bristles making up the bristle tufts  66 ,  90  are not shown for the sake of simplicity. Like the bristle tufts  66 , the bristle tufts  90  can be assembled to the dowel  56  by pressing bristles into the bristle holes  96  and securing the bristles using a fastener (not shown), such as the staple  88  shown in  FIG.  5   . The height and stiffness of the bristle tufts  66 ,  90  can be substantially equal, such that there is a substantially constant bristle diameter and stiffness. Alternatively, the height and stiffness of the bristle tufts  66 ,  90  can vary. 
     Like the first example, the dowel  56  can be integrally molded in one-piece using a two-plate mold. In the example shown, the bristle ridges  90  in quadrants I and III are not provided with bristle stiffeners to avoid creating undercuts on the dowel  56 , such that the only bristle stiffeners  68  provided on the dowel  56  are drafted in the line of draw, which may be defined along the Z axis. However, the bristle tufts  66 ,  92  can still be provided in all four quadrants I-IV to maintain a more balanced contact with the surface to be cleaned as the brushroll  40  rotates. 
       FIG.  12    is a close-up cross-sectional view, similar to  FIG.  5   , of a brushroll  40  according to a third example of the present disclosure, in which like elements are identified with the same reference numerals. The brushroll  40  can be used in place of the brushroll  40  on the vacuum cleaner  10  shown in  FIGS.  1 - 2   , and can be substantially similar to the brushroll  40  shown the first example of  FIG.  3   , save for the provision of a shim  98  between the bristle stiffener  68  and the bristle tufts  66 . The shim  98  is positioned within the gap G between the inner stiffener surface  82  and the closest portion of the bristle tuft  66 . The shim  98  can be added after injection molding to further reduce the effective size of the gap G. In one example, the size of the gap as molded can be approximately 3 mm and the thickness of the shim  98  can be approximately 2.5 mm, providing an effective gap of 0.5 mm. 
     The shim  98  can be a strip of flexible material, such as a hard rubber, which is attached to the inner stiffener surface  82  and extends the length and height of the bristle stiffener  68 . In one example, the shim  98  can be adhered to the inner stiffener surface  82  using an adhesive. 
       FIG.  13    is a close-up cross-sectional view similar to  FIG.  5    of a brushroll  40  according to a fourth example of the present disclosure. The brushroll  40  can be used in place of the brushroll  40  on the vacuum cleaner  10  shown in  FIGS.  1 - 2   , and can be substantially similar to the brushroll  40  shown the third example of  FIG.  12   , except that the shim  98  can be strip of plastic or aluminum that is inserted into the dowel  56  after tufting. In this case, the shim  98  can be provided with tabs  100  that lock into holes drilled into the molded dowel  56 . The shim  100  can be a stamped or molded part that can bend along the contour of the bristle stiffener  68 . 
       FIG.  14    is a perspective view of a brushroll  40  according to a fifth example of the present disclosure, in which like elements are identified with the same reference numerals. The brushroll  40  can be used in place of the brushroll  40  on the vacuum cleaner  10  shown in  FIGS.  1 - 2   , and can be substantially similar to the brushroll  40  shown the first example of  FIG.  3   , save for the provision of additional rows of bristle tufts. 
     A plurality of bristle ridges  102  can project or extend from the exterior surface of the brush dowel  56  and are arranged in two opposing rows extending along the dowel  56  closely adjacent to the opposing rows of bristle ridges  64 , which allows the bristle ridges  64 ,  102  to be easily moldable with the dowel  56 . A plurality of bristle tufts  104  can project or extend from each bristle ridge  102 . Each bristle tuft  104  can include a plurality of flexible bristles, which may be made from a durable polymer material such as nylon or polyester, for example. 
     The bristle tufts  104  can be softer than the bristle tufts  66 . For example, the bristles of the non-stiffened bristle tufts  104  can have a diameter of approximately 0.1 mm, with a 2.5 mm tuft diameter, and the bristles of the stiffened bristle tufts  66  can have a diameter of approximately 0.15-0.25 mm with 4.9 mm tuft diameter. The advantage of the additional row of non-stiffened bristle tufts  104  is that more of the 360 degrees of the dowel  56  will be covered with bristles, while still being moldable in a two plate injection mold without additional movable slides or lifters. The variation in tuft properties accommodates multiple floor surfaces, including both carpets and bare floors. 
     The bristle tufts  104  (and likewise the bristle ridges  102 ) can have a repeating pattern which generally follows the pattern of the rows of bristle tufts  66 . The bristle ridges  102  are positioned adjacent to a front side of the bristle ridges  64 , with “front” in this case being defined in relation of the direction of rotation A, such that upon rotation the bristle tufts  104  engage the surface to be cleaned just before the bristle tufts  66 . The front bristle ridges  102  are not provided with bristle stiffeners. Circumferential gaps  94  extend around the dowel  56  and separate adjacent bristle ridges  64 ,  102  and allow the rotating brushroll  40  to clear ribs on the lower housing  34  that prevent carpet from getting drawn into the suction nozzle opening  42  ( FIG.  1   ). 
       FIG.  15    is a close-up view of a portion of the brushroll  40  from  FIG.  14   . Each leading or front bristle ridge  102  has a leading surface  106  and a trailing surface  108 , as defined by the direction of rotation, which project from the exterior surface of the brush dowel  56  and are joined by two end surfaces  110 ,  112  and an upper surface  114 . The trailing surface  108  of the front bristle ridge  102  joins the leading surface  72  of the trailing or rear bristle ridge  64 . Likewise, the end surfaces  110 ,  112  join the end surfaces  76 ,  78 . 
     The leading surface  106  and the trailing surface  108  can be non-planar, with a longitudinal twist formed in the leading surface  106  and the trailing surface  108 , such that the second end surface  112  is radially offset from the first end surface  110 . During rotation, bristle tufts  104  near the first end surface  110  will contact the surface to be cleaned first, with the bristle tufts  106  closer to the second end surface  112  sequentially following. 
       FIG.  16    is a cross-sectional view through line XVI-XVI of  FIG.  14   . Bristle holes  116  can be formed in the upper surface  114  and receive the bristle tufts  104 . The individual bristles making up the bristle tufts  66 ,  104  are not shown for the sake of simplicity. Like the bristle tufts  66 , the bristle tufts  104  can be assembled to the dowel  56  by pressing bristles into the bristle holes  116  and securing the bristles using a fastener, such as a staple (not shown), such as the staple  88  shown in  FIG.  5   . 
     The non-stiffened bristle tufts  104  can be dissimilar from the stiffened bristle tufts  66 . For example, the stiffened bristle tufts  66  can extend substantially normal to the dowel  56 , such that a centerline S passing through one of the bristle tufts  66  intersects the rotational axis X defined by the shaft  58 , while the non-stiffened bristle tufts  104  can extend at an angle from the dowel  56 , such that a centerline N passing through one of the bristle tufts  104  is offset from the rotational axis X defined by the shaft  58 . The bristle tufts  66 ,  104  can also be trimmed to substantially the same diameter, such that there is a substantially constant bristle diameter D, which can lower manufacturing costs. During operation the angled, non-stiffened bristle tufts  104  expand to a diameter greater than D due to the centripetal force from the rotating brushroll  40 , allowing the softer bristles to selectively contact a lower floor surface, such as a bare floor. The stiffened bristle tufts  66  do not expand due to the centripetal force, keeping the stiffer bristles out of contact with the lower floor surface. The non-stiffened bristle tufts  104  will sweep, but not scratch, a bare floor. The stiffened bristle tufts  66  only contact higher surfaces like carpet, which is more forgiving and requires more of a beating action to be effectively cleaned. 
     Like the first example, the dowel  56  can be integrally molded in one-piece using a two-plate mold. In the example shown, the bristle ridges  102  in quadrants I and III are not provided with bristle stiffeners to avoid creating undercuts on the dowel  56 , such that the only bristle stiffeners  68  provided on the dowel  56  are drafted in the line of draw, which may be defined along the Z axis. However, the bristle tufts  66 ,  104  can still be provided in all four quadrants I-IV to maintain a more balanced contact with the surface to be cleaned as the brushroll  40  rotates. 
       FIG.  17    is a perspective view of a brushroll  40  according to a sixth example of the present disclosure, in which like elements are identified with the same reference numerals. The brushroll  40  can be used in place of the brushroll  40  on the vacuum cleaner  10  shown in  FIGS.  1 - 2   , and can be substantially similar to the brushroll  40  shown the fifth example of  FIG.  14 - 16   , save for the rows of non-stiffened bristle tufts  104 . In this example, the non-stiffened bristle tufts  104  are normal to the dowel  56 , whereby the non-stiffened bristle tufts  104  lie at an angle with respect to their position in  FIG.  14   , as shown by the phantom lines indicating the position of the non-stiffened bristle tufts  104  in  FIG.  14   . 
       FIG.  18    is a cross-sectional view through the brushroll  40  of  FIG.  17   . In this example, like the stiffened bristle tufts  66 , the non-stiffened bristle tufts  104  can extend substantially normal to the dowel  56 , such that the centerline N passing through one of the bristle tufts  104  intersects the rotational axis X defined by the shaft  58 . Also, the non-stiffened bristle tufts  104  are not trimmed to the same diameter as the stiffened bristle tufts  66 , such that the non-stiffened bristle tufts  104  are longer and define a larger bristle diameter D N  than the stiffened bristle tufts  66 , which are shorter and define a smaller bristle diameter D S . The non-stiffened bristle tufts  104  will sweep, but not scratch, a bare floor. The stiffened bristle tufts  66  only contact higher surfaces like carpet, which is more forgiving and requires more of a beating action to be effectively cleaned. 
     Like the first example, the dowel  56  can be integrally molded in one piece using a two-plate mold. In the example shown, the bristle ridges  102  in I and III are not provided with bristle stiffeners to avoid creating undercuts on the dowel  56 , such that the only bristle stiffeners  68  provided on the dowel  56  are drafted in the line of draw, which may be defined along the Z axis. However, the bristle tufts  66 ,  104  can still be provided in all four quadrants I-IV to maintain a more balanced contact with the surface to be cleaned as the brushroll  40  rotates. 
       FIG.  19    is a perspective view of a brushroll  40  according to a seventh example of the present disclosure, in which like elements are identified with the same reference numerals. The brushroll  40  can be used in place of the brushroll  40  on the vacuum cleaner  10  shown in  FIGS.  1 - 2   , and can be substantially similar to the brushroll  40  shown the first example of  FIG.  3   , save for the provision of additional rows of bristles, the orientation of the rows, and the provision of some non-stiffened bristles in the rows. In the example shown, four helical rows R of bristles are provided, with each row made up of a repeating pattern of stiffened bristles and non-stiffened bristles. The rows R can be spaced substantially evenly about the dowel  56  to maintain a more balanced contact with the surface to be cleaned as the brushroll  40  rotates. 
     The stiffened bristle tufts  66  are substantially similar to those described above, and are provided on bristle ridges  64  having bristle stiffeners  68 . A plurality of bristle ridges  118  can project or extend from the exterior surface of the brush dowel  56  and are arranged in between the bristle ridges  64 . The bristle ridges  118  are not provided with bristle stiffeners. A plurality of bristle tufts  120  can project or extend from each bristle ridge  118 . Each bristle tuft  120  can include a plurality of flexible bristles, which may be made from a durable polymer material such as nylon or polyester, for example. The bristle tufts  120  can have a stiffness substantially the same as the bristle tufts  66 , and can flex as the brushroll  40  rotates. Circumferential gaps  94  extend around the dowel  56  and separate adjacent bristle ridges  64 ,  120  and allow the rotating brushroll  40  to clear ribs on the lower housing  34  that prevent carpet from getting drawn into the suction nozzle opening  42  ( FIG.  1   ). 
       FIG.  20    is a close-up view of a portion of the brushroll  40  from  FIG.  19   . Each non-stiffened bristle ridge  118  has a leading surface  122  and a trailing surface  124 , as defined by the direction of rotation, which project from the exterior surface of the brush dowel  56  and are joined by two end surfaces  126 ,  128  and an upper surface  130 . The leading surface  122  and the trailing surface  124  can be non-planar, with a longitudinal twist formed in the leading surface  122  and the trailing surface  124 . During rotation, bristle tufts  120  near the second end surface  128  will contact the surface to be cleaned first, with the bristle tufts  120  closer to the first end surface  126  sequentially following. 
     In the example shown, the bristle tufts  66 ,  120  can have a repeating helically-extending pattern, where the circumferential gaps  94  separate the stiffened and non-stiffened bristle ridges  64 ,  118 , such that the first end surface  76  of one stiffened bristle ridge  64  is aligned with the second end surface  128  of one adjacent non-stiffened bristle ridge  118  and the second end surface  78  of the same stiffened bristle ridge  64  is aligned with the first end surface  126  of the other adjacent non-stiffened bristle ridge  118 , but is radially offset from the first end surface  76 . 
       FIG.  21    is a cross-sectional view through line XXI-XXI of  FIG.  19   . Bristle holes  132  can be formed in the non-stiffened bristle ridge  118  and receive the bristle tufts  120 . The individual bristles making up the bristle tufts  66 ,  120  are not shown for the sake of simplicity. Like the bristle tufts  66 , the bristle tufts  120  can be assembled to the dowel  56  by pressing bristles into the bristle holes  132  and securing the bristles using a fastener (not shown), such as the staple  88  shown in  FIG.  5   . 
     The non-stiffened bristle tufts  120  can be dissimilar from the stiffened bristle tufts  66 . For example, the non-stiffened bristle tufts  120  can extend substantially normal to the dowel  56 , such that the centerline N passing through one of the bristle tufts  120  intersects the rotational axis X defined by the shaft  58 , while the stiffened bristle tufts  66  can extend at an angle from the dowel  56 , such that the centerline S passing through one of the bristle tufts  66  is offset from the rotational axis X defined by the shaft  58 . Also, the non-stiffened bristle tufts  120  are not trimmed to the same diameter as the stiffened bristle tufts  66 , such that the non-stiffened bristle tufts  120  are longer and define a larger bristle diameter D N  than the stiffened bristle tufts  66 , which are shorter and define a smaller bristle diameter D S . 
     In this example, the stiffened bristle tufts  66  are angled into the direction of rotation, increasing the aggressiveness of the beating action on carpet. This allows the stiffened bristle tuft  66  to be manufactured farther from the bristle stiffener  68  while maintaining a perpendicular orientation to the surface to be cleaned after the bristle tuft  66  is deflected by the carpet and until it comes into contact with the bristle stiffener  68 . 
     Like the first example, the dowel  56  can be integrally molded in one-piece using a two-plate mold. In the example shown, the bristle ridges  118  in quadrants I and III are not provided with bristle stiffeners to avoid creating undercuts on the dowel  56 , such that the only bristle stiffeners  68  provided on the dowel  56  are drafted in the line of draw, which may be defined along the Z axis. However, the bristle tufts  66 ,  120  can still be provided in all four quadrants I-IV to maintain a more balanced contact with the surface to be cleaned as the brushroll  40  rotates. 
       FIG.  22    is a perspective view of a brushroll  40  according to an eighth example of the present disclosure, in which like elements are identified with the same reference numerals. The brushroll  40  can be used in place of the brushroll  40  on the vacuum cleaner  10  shown in  FIGS.  1 - 2   , and can be substantially similar to the brushroll  40  shown the seventh example of  FIG.  19 - 21   , save for the rows of non-stiffened bristle tufts  120 . In this example, the non-stiffened bristle tufts  120  are offset with respect to their position in  FIG.  19   , as shown by the phantom lines indicating the position of the non-stiffened bristle tufts  120  in  FIG.  19   . 
       FIG.  23    is a cross-sectional view through the brushroll  40  of  FIG.  22   . In this example, like the stiffened bristle tufts  66 , the non-stiffened bristle tufts  120  can extend at an angle from the dowel  56 , such that the centerline N passing through one of the bristle tufts  120  is offset from the rotational axis X defined by the shaft  58 . The bristle tufts  66 ,  120  can also be trimmed to substantially the same diameter, such that there is a substantially constant bristle diameter D, which can lower manufacturing costs. During operation the angled, non-stiffened bristle tufts  120  expand to a diameter greater than D due to the centripetal force from the rotating brushroll  40 , allowing the softer bristles to selectively contact a lower floor surface, such as a bare floor. The stiffened bristle tufts  66  do not expand due to the centripetal force, keeping the stiffer bristles out of contact with the lower floor surface. The non-stiffened bristle tufts  104  will sweep, but not scratch, a bare floor. The stiffened bristle tufts  66  only contact higher surfaces like carpet, which is more forgiving and requires more of a beating action to be effectively cleaned. 
     In this example, the stiffened bristle tufts  66  are angled into the direction of rotation, increasing the aggressiveness of the beating action on carpet. This allows the stiffened bristle tuft  66  to be manufactured farther from the bristle stiffener  68  while maintaining a perpendicular orientation to the surface to be cleaned after the bristle tuft  66  is deflected by the carpet and until it comes into contact with the bristle stiffener  68 . 
     Like the first example, the dowel  56  can be integrally molded in one-piece using a two-plate mold. In the example shown, the bristle ridges  118  in quadrants I and III are not provided with bristle stiffeners to avoid creating undercuts on the dowel  56 , such that the only bristle stiffeners  68  provided on the dowel  56  are drafted in the line of draw, which may be defined along the Z axis. However, the bristle tufts  66 ,  104  can still be provided in all four quadrants I-IV to maintain a more balanced contact with the surface to be cleaned as the brushroll  40  rotates. 
       FIG.  24    is a perspective view of a brushroll  40  according to a ninth example of the present disclosure, in which like elements are identified with the same reference numerals. The brushroll  40  can be used in place of the brushroll  40  on the vacuum cleaner  10  shown in  FIGS.  1 - 2   , and can be substantially similar to the brushroll  40  shown the first example of  FIG.  3   , save for the agitation features provided on the dowel  56 , as described below. 
     A plurality of bristle ridges  134  project or extend from the exterior surface of the brush dowel  56 . A plurality of bristle tufts  136  can project or extend from each bristle ridge  134 . Each bristle tuft  136  can include a plurality of flexible bristles, which may be made from a durable polymer material such as nylon or polyester, for example. 
     At least one bristle stiffener  138  projects or extends from each bristle ridge  134 . The bristle stiffeners  138  are generally coextensive with the bristle tufts  136 , and can extend generally along the entire length of the bristle ridges  134 . The bristle stiffeners  138  are positioned adjacent to a rear side of the bristle tufts  136 , with “rear” in this case being defined in relation of the direction of rotation A. The bristle stiffeners  138  are substantially rigid, and do not flex as the brushroll  40  rotates. The bristle tufts  136  are less stiff than the bristle stiffeners  138 , can flex somewhat as the brushroll  40  rotates, although the presence bristle stiffeners  138  prevents at least some of the flexure that that bristle tufts  136  would otherwise experience without the bristle stiffeners  138 . 
     As shown herein two opposing bristle ridges  134  extend along the dowel  56 , with each bristle ridge  134  formed as an elongated strip  140  wrapping around the circumference of the dowel and defining a row of bristle tufts  136 . Each strip  140  has multiple bristle tufts  136  and a single, continuous bristle stiffener  138 . The bristle ridges  134 , and thus the bristle tufts  1336  and stiffeners  138 , are arranged in a generally helix pattern spiraling around the outer circumference of the brush dowel  56 . 
       FIG.  25    is a plan view of the dowel  56 . The dowel  56  can be provided with pairs of molded dowel ridges  144  that define a slot  146  in which the strips  140  can be inserted. The brush dowel  56  can be integrally molded, as described above. 
       FIG.  26    is a partially exploded view of the brushroll  40  from  FIG.  24   . The dowel ridges  144  can be provided with one or more holes  148  for receiving a mechanical fastener, such as screw  150 , for securing the strips  140  to the dowel  56 . The bend of the dowel ridges  1400  allow the holes  148  to be drilled into the dowel  56  in the line of draw. The strips  140  can likewise be provided with holes  154  for receiving the screws  150 . To assemble the bristles ridges  134  to the dowel  56 , the strips  140  can be slid in between the dowel ridges  144  and secured with the screws  150 . As shown, the bristles tufts  136  can be tufted into the strips  140  prior to assembling the strips  140  with the dowel  56 . 
       FIG.  27    is a cross-sectional view through line XXVII-XXVII of  FIG.  24   . Each dowel ridge  144  has a leading surface  160  and a trailing surface  162 , as defined by the direction of rotation, that project from the exterior surface of the brush dowel  56 . Each bristle ridges  134  has a leading surface  164  and a trailing surface  166  that project from the exterior surface of the brush dowel  56  and are joined by an upper surface  168 . The leading surface  164  of the bristle ridge  134  can be flush against trailing surface  162  of the dowel ridge  144 . The bristle stiffener  138  can be integrally formed with the bristle ridge  134 , and can include an inner stiffener surface  172  which extends upwardly form the upper surface  170  to a stiffener edge  174  which joins the upper end of the trailing surface  166 . 
     Bristle holes  176  can be formed in the upper surface  170  and extend at least partially into the bristle ridge  134 . The bristle tufts  136  can be assembled to the dowel  56  by pressing bristles into the bristle holes  176  and securing the bristles using a fastener (not shown), such as a staple  88  as in  FIG.  5   . 
     The bristle stiffener  138  can be adjacent to the bristle holes  176 , such that there is a small gap G between the inner stiffener surface  172  and the closest portion of the bristle tuft  136 . In one example, the gap G can be approximately 0.5 mm. 
       FIG.  28    is a perspective view of a brushroll  40  according to a tenth example of the present disclosure, in which like elements are identified with the same reference numerals. The brushroll  40  can be used in place of the brushroll  40  on the vacuum cleaner  10  shown in  FIGS.  1 - 2   , and can be substantially similar to the brushroll  40  shown the first example of  FIG.  3   , save for the agitation features provided on the dowel  56 , as described below. 
     In the example shown, multiple helical rows R of bristles are provided, with each row made up of a repeating pattern of stiffer bristles  178  and softer bristles  180 . The rows R can be spaced substantially evenly about the dowel  56 , which maintains a balanced contact with the surface to be cleaned as the brushroll  40  rotates. Preferably, 2-4 rows R are provided. 
     A plurality of bristle ridges  182  project or extend from the exterior surface of the brush dowel  56 , with the stiffer bristles  178  projecting or extending from alternating bristle ridges  182  and the softer bristles  180  projecting or extending from the intervening bristle ridges  182 . Each bristle tuft  178 ,  180  can include a plurality of flexible bristles, which may be made from a durable polymer material such as nylon or polyester, for example. The bristle ridges  182  do not include bristle stiffeners. Circumferential gaps  94  extend around the dowel  56  and separate adjacent bristle ridges  182  and allow the rotating brushroll  40  to clear ribs on the lower housing  34  that prevent carpet from getting drawn into the suction nozzle opening  42  ( FIG.  1   ). 
     By providing a combination stiffer and softer bristles  178 ,  180 , the brushroll  40  is effective on multiple types of floor surfaces. The stiffer bristles  178  allow deeper penetration of carpet, while the softer bristles  180  perform well on hard surfaces including bare floors. The stiffer and softer bristles  178 ,  180  can be trimmed to substantially the same diameter, such that there is a substantially constant bristle diameter, which can lower manufacturing costs. Alternatively, the softer bristles  180  can be longer than the stiffer bristles  178 . 
     During operation the softer bristles  180  can expand to a larger diameter due to the centripetal force from the rotating brushroll  40 , allowing the softer bristles  180  to selectively contact a lower floor surface, such as a bare floor. The stiffer bristles  178  do not expand due to the centripetal force, keeping the stiffer bristles  178  out of contact with the lower floor surface. The softer bristles  180  will sweep, but not scratch, a bare floor. The stiffer bristles  178  only contact higher surfaces like carpet, which is more forgiving and requires more of a beating action to be effectively cleaned. 
     The brush dowel  56 , including the bristle ridges  182 , can be integrally molded, as described above, with the bristle tufts  178 ,  180  assembled to the dowel  56  by pressing bristles into bristle holes (not shown) drilled into the molded dowel  56  and securing the bristles using a fastener (not shown), such as a staple  88  as in  FIG.  5   . 
       FIG.  29    is a perspective view of a brushroll  40  according to an eleventh example of the present disclosure, in which like elements are identified with the same reference numerals. The brushroll  40  can be used in place of the brushroll  40  on the vacuum cleaner  10  shown in  FIGS.  1 - 2   , and can be substantially similar to the brushroll  40  shown the first example of  FIG.  3   , save for the agitation features provided on the dowel  56 , as described below. 
     A plurality of bristle ridges  188  project or extend from the exterior surface of the brush dowel  56 . A plurality of bristle tufts  190  can project or extend from each bristle ridge  188 . Each bristle tuft  190  can include a plurality of flexible bristles, which may be made from a durable polymer material such as nylon or polyester, for example. 
     The bristle ridges  188  can be formed as helical ribs  192  which extend around the circumference of the dowel  56  at least one time. The helical ribs  192  have a relatively narrow width along the longitudinal axis X in comparison to the width of the bristle ridges of the previous examples. As shown herein, each helical rib  192  extends around the dowel  56  multiple times, from a first end  194  to a second end  196 . The first and second ends  194 ,  196  of adjacent helical ribs  192  can partially overlap, such that an effectively continuous helical bristle ridge  188  is provided along the length of the dowel  56 , but are laterally spaced from each other so that the rotating brushroll  40  can clear ribs on the lower housing  34  that prevent carpet from being drawn into the suction nozzle opening  42  ( FIG.  1   ). The turns of the helical ribs  192  can be relatively close together, with a spacing of 20 mm and a pitch angle of 60 degrees. The helical ribs  192  can act as an auger which directs air and debris toward the suction nozzle opening  42  ( FIG.  2   ). 
     Each helical rib  192  can have multiple bristle tufts  190  extending radially from an outer peripheral surface of the helical rib  192 . The tufts  190  of each helical rib  192  are spaced from each other such that the bristles of one tuft  190  do not intersect or touch the bristles from another tuft  190 . The tufts  190  are organized across the dowel  56  in an opposing helical pattern to the helical rib  192 . This provides a precessing motion to the tufts  190  as the brushroll  40  rotates, akin to the action of fingers drumming on a table, which opens or parts carpet fibers in a spaced, even path. 
     The brush dowel  56 , including the bristle ridges  188 , can be integrally molded, as described above, with the bristle tufts  190  assembled to the dowel  56  by pressing bristles into bristle holes (not shown) drilled into the molded dowel  56  and securing the bristles using a fastener (not shown), such as a staple  88  as in  FIG.  5   . 
       FIG.  30    is a perspective view of a brushroll  40  according to a twelfth example of the present disclosure, in which like elements are identified with the same reference numerals. The brushroll  40  can be used in place of the brushroll  40  on the vacuum cleaner  10  shown in  FIGS.  1 - 2   , and can be substantially similar to the brushroll  40  shown the first example of  FIG.  3   , save for the agitation features provided on the dowel  56 , as described below. 
     A plurality of bristle ridges  200  project or extend from the exterior surface of the brush dowel  56 . A plurality of bristle tufts  202  can project or extend from each bristle ridge  200 . Each bristle tuft  202  can include a plurality of flexible bristles, which may be made from a durable polymer material such as nylon or polyester, for example. Alternatively, instead of multiple discrete tufts  202  as shown herein, a continuous brush strip composed of a plurality of flexible bristles can be provided on each bristle ridge  200 . 
     The bristle ridges  200  can be formed as discs  204  which extend around the circumference of the dowel  56 , with each disc  204  having multiple bristle tufts  202  extending radially from an outer peripheral surface  206  of the disc  204 . The tufts  202  of each disc  204  are spaced from each other such that the bristles of one tuft  202  do not intersect or touch the bristles from another tuft  202 . 
     The bristle ridges  200  can be divided into two groups, a first group  208  associated with the pulley end of the dowel  56  and a second group  210  associated the opposing end of the dowel  56 . With each group, the discs  204  can be oriented along parallel planes, but the discs  204  are all angled relative to a plane P perpendicular to the ends of the dowel  56 . The discs  204  of the first group  208  can oriented at a positive acute angle relative to the plane P and the discs  204  of the second group  210  can oriented at a negative acute angle relative to the plane P. The leaning discs  204  effective oscillate the bristle tufts  202  back and forth as the brushroll  40  rotates. While not shown, radially aligned gaps can be formed in each disc  204  to effectively form a longitudinal slot across the length of the dowel  56  for the insertion of scissors for cutting hair that wraps around the dowel  56 . 
     The brush dowel  56 , including the bristle ridges  200 , can be integrally molded, as described above, with the bristle tufts  202  assembled to the dowel  56  by pressing bristles into bristle holes (not shown) drilled into the molded dowel  56  and securing the bristles using a fastener (not shown), such as a staple  88  as in  FIG.  5   . The bristle tufts  202  can be tufted coplanar relative to the outer peripheral surface  206  of the disc  204 . This allows the discs  204  to remain relatively thin since the drilled holes will not be too close to the sides of the disc  204  in this orientation. 
       FIG.  31    is a schematic view of a bristle tufting tool  214  according to a thirteenth example of the present disclosure. The tufting process is illustrated on the brushroll  40  of the first example, but may apply to tufting any type of brushroll having a bristle stiffener. As described above with respect to  FIG.  5   , the bristle stiffener  68  is adjacent to the bristle holes  86  for the bristle tufts (not shown), such that there is a small gap between the inner stiffener surface and the closest portion of the bristle tuft. During manufacturing, it is difficult to place the bristle tuft close to the bristle stiffener  68  because the bristles are guided by a sleeve during tufting.  FIG.  31    shows a tufting tool  214  including a sleeve  216  with a notch  218  cut out of one side so that the sleeve  216  can clear the bristle stiffener  68 . Along with the sleeve  216 , the bristle stiffener  68  at the notch  218  can act as a guide to the tuft insertion on the stiffener side. This allows the bristle tuft to be located very close to the bristle stiffener  68 .  FIG.  32    is a bottom view of the tufting tool  216 . 
       FIGS.  33 - 37    illustrate a method of tufting a brushroll dowel  56  using the tufting tool  214  of  FIGS.  31 - 32   . Using the tufting method, bristle tufts can be tufted close to a bristle stiffener on a brushroll dowel. In some versions, the tufting method may virtually eliminate any gap between the bristle tuft and the adjacent bristle stiffener  68  such that the bristle tuft is adjacent and in register with the stiffener  68 . However, in other versions, a small gap may remain. 
     The method may be performed using a CNC tufting machine, a portion of which is schematically illustrated in the figures, that has a frame with a holding fixture that is configured to mount the dowel  56  and move the dowel  56  relative to the tufting tool  214  during operation. The tufting machine can include a supply of bristle material  220  and a supply of fasteners  88 , such as staples, anchors, or wedges, for securing bristle tufts to the dowel  56 . In addition to the tufting tool  214 , the machine can further include a bristle cutting blade  222  and a bristle driving member  224 , all of which can be adapted to reciprocate vertically relative to the dowel  56 . 
     In one example, the holding fixture of the tufting machine can be configured to rotate the dowel  56  about its longitudinal axis and move the dowel  56  laterally along its longitudinal axis in accordance with output from a controller. While not shown herein, the tufting machine can include one or more sensors and controllers that output signals to various components on the machine according to a pre-determined tufting program and desired tuft pattern. Furthermore, the tufting machine can include a bristle hole drilling station, or alternatively the bristle holes  86  can be pre-drilled in the dowel  56  on a separate machine. 
     With reference to  FIG.  33   , the sleeve  216  of the tufting tool  214  includes a central bore  226  that tapers from a larger diameter at a top or inlet opening  228  of the sleeve  216  to a smaller diameter at a bottom or outlet opening  230  of the sleeve  216 . The notch  218  is provided adjacent to the outlet opening  230 . The bore  226  is configured to guide the driving member  224  and bristle bundles during the tufting operation. 
     The supply of bristle material  220  can be provided on a supply reel that can be connected to a controller and feeder mechanism configured to automatically feed a bundle of bristle filaments into the machine during operation. The cutting blade  222  can be associated with the feeder mechanism and configured to cut a bristle bundles to a predetermined length prior to insertion into the dowel  56 . 
     The driving member  224  can include a rod-like member with a longitudinal slot  232  for delivering fasteners  88  to the bottom of the driving member where they are driven into the dowel. Alternatively, the fasteners  88  can be provided in a magazine or via a bulk hopper that is configured to selectively introduce a fastener  88  near the bottom of the sleeve  216  just prior to impact by the driving member  224 . 
     In operation, a dowel  56  with a pre-formed bristle hole  86  can be loaded into the holding fixture and the tufting machine can be actuated. The holding fixture can automatically align the bristle hole  86  with the longitudinal axis of the tufting sleeve  216  by rotating and/or shifting the dowel  56  about its longitudinal axis according to output signals from the controller and sensor feedback. 
     To begin tufting, the tufting tool  214  descends downwardly and bottoms out on the dowel  56  with the bristle stiffener  68  nested within the notch  218  and the outlet opening  230  at least partially aligned with the bristle hole  86 . The supply reel feeds bristle material  220  into the machine through an opening  234  (shown in  FIG.  32   ) in the top of the tufting sleeve  216 . The cutting blade  222  cuts a bristle bundle  236  to a predetermined length. 
     Referring to  FIG.  34   , the driving member  224  descends vertically within the tufting sleeve  216  and pushes the bristle bundle  236  through the bore  226  of the tufting sleeve  216 . 
     Referring to  FIG.  35   , as the bristle bundle  236  is pushed through the tufting sleeve  216 , the bristle bundle  236  folds inwardly due to the tapered shape of the bore  226 , such that the ends of the bristle bundle  236  converge towards the driving member  224  and the middle of the bristle bundle  236  is driven toward the bottom of the bristle hole  86 . 
     Referring to  FIG.  36   , as the bristle bundle  236  passes the notch  218 , the portion of the bristle stiffener  68  aligned with the notch  218  at least partially guides the bristle bundle  236  out of the outlet opening  230  and into the bristle hole  86 . Thus, the bristle bundle  236  is entirely surrounded by a combination of the sleeve  216  and a portion of the bristle stiffener  68  during insertion, with at least some of the bristles positioned in register with the bristle stiffener  68 . 
     Referring to  FIG.  37   , once the bristle bundle  236  is fully pressed within the bristle hole  86 , the driving member  224  inserts a fastener  88  at the bottom of the bristle hole  86  to retain the bristles deeply and securely within the bristle hole  86 . The driving member  224  and tufting tool  214  can then be raised away from the dowel  56 . It is noted that while the method is illustrated for a single tuft, brushrolls most commonly include multiple tufts of bristles; as such, it is understood that the method can be repeated multiple times in order to fully tuft the dowel  56 . After the tufting operation is complete, additional operations can be commenced, such as a tuft trimming operation and a rotational balancing operation, for example. 
     The vacuum cleaner  10  and various brushrolls  40  disclosed herein provide improved cleaning performance and ease of manufacture. One advantage that may be realized in the practice of some examples of the described vacuum cleaner  10  and various brushrolls  40  is that the bristle stiffeners are formed as one-piece with the brushroll dowel in a two-piece or clamshell-type mold, with the bristle stiffeners drafted in the line of draw. This eliminates undercuts from the dowel, making it possible to integrally mold the bristle stiffeners with the dowel using a two-plate mold, which is much less complex and costly than other types of molds. 
     Another advantage that may be realized in the practice of some examples of the described tufting tool and associated tufting method is that bristle tufts can be tufted close to a bristle stiffener on a brushroll dowel so as to virtually eliminate any gap between the bristle tuft and the adjacent bristle stiffener. 
     While the present disclosure has been specifically described in connection with certain specific examples thereof, it is to be understood that this is by way of illustration and not of limitation. Reasonable variation and modification are possible with the scope of the foregoing disclosure and drawings without departing from the spirit of the invention which, is defined in the appended claims. Hence, specific dimensions and other physical characteristics relating to the examples disclosed herein are not to be considered as limiting, unless the claims expressly state otherwise.