Patent Publication Number: US-10786127-B2

Title: Cleaner head for a vacuum cleaner

Description:
REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 15/679,893, filed Aug. 17, 2017, which is a continuation of U.S. patent application Ser. No. 14/909,399, filed Feb. 1, 2016, which is a national stage application under 35 USC 371 of International Application No. PCT/GB2014/052259, filed Jul. 24, 2014, which claims the priority of United Kingdom Application No. 1313707.0, filed Jul. 31, 2013, the entire contents of each of which are incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to a cleaner head for a vacuum cleaner, and particularly, although not exclusively, relates to a cleaner head for a hand-held vacuum cleaner. 
     BACKGROUND OF THE INVENTION 
     Cleaner heads for vacuum cleaners typically comprise a brush bar located within a housing. A suction opening is provided in a lower surface of the housing, which is commonly known as a sole plate, through which dirt bearing air is drawn into the cleaner head. 
     A problem associated with conventional cleaner heads is that the close proximity required between the sole plate and the surface being cleaned in order to maintain pick-up performance means that large debris tends to be pushed across the surface being cleaned by the cleaner head rather than being drawn through the suction opening into the cleaner head. 
     SUMMARY OF THE INVENTION 
     According to a first aspect of the invention there is provided a cleaner head for a vacuum cleaner, comprising an agitator in the form of a brush bar, the brush bar comprising a plurality of radially extending bristles and a sealing material disposed between the bristles, the sealing material extending over substantially the entire circumferential and axial extent of the regions of the brush bar between the bristles; a housing defining a chamber which at least partially surrounds the brush bar, a dirty air inlet in a lower part of the chamber and a front opening that exposes the brush bar at the front of the housing, the brush bar being supported for rotation with respect to the housing and arranged in the chamber such that the brush bar seals against the housing thereby restricting flow of air through the front opening. 
     The sealing material may be a deformable material. In particular, the sealing material may be a resiliently deformable material. 
     The brush bar may substantially occlude the front opening. 
     The radial extent of the bristles may be equal to the radial extent of the sealing material. The radial extent of the bristles may be greater than the radial extent of the sealing material. 
     The cleaner head may be provided with a support for supporting the cleaner head on a surface being cleaned, the brush bar being arranged such that, in use, the bristles contact the surface being cleaned. The bristles may extend below the support. 
     The sealing material may be arranged such that, in use, the sealing material is spaced away from the surface being cleaned by the support. 
     The front opening may be defined by an upper front edge and opposing side edges of the housing. The upper front edge may be above the rotational axis of the brush bar. The upper front edge may be below the top of the brush bar. 
     The front opening may extend in a plane which is forward of the longitudinal axis of the brush bar. At least a portion of the brush bar may protrude through the front opening. 
     A top portion of the housing may extend forwardly over the top of the brush bar to form a guard that prevents debris from being flung upwardly by the brush bar away from the housing. 
     The sealing material may seal against an inner surface of the front portion of the housing. 
     The bristles may be arranged in a plurality of rows (starts) extending longitudinally with respect to the brush bar. The sealing material may comprise a tufted material. 
     The bristles may comprise carbon fibre bristles having a stiffness which is greater than the stiffness of the sealing material in a radial direction. 
     The cleaner head may comprise a rear roller. 
     According to a second aspect of the invention there is provided a vacuum cleaner comprising a cleaner head in accordance with the first aspect of the invention. 
     According to a third aspect of the invention there is provided a brush bar comprising a plurality of radially extending bristles and a sealing material disposed between the bristles, the sealing material extending over substantially the entire circumferential and axial extent of the regions of the brush bar between the bristles. 
     The sealing material may be a deformable material. In particular, the sealing material may be a resiliently deformable material. 
     The radial extent of the bristles may be equal to the radial extent of the sealing material. 
     The radial extent of the bristles may be greater than the radial extent of the sealing material. 
     The sealing material may comprise a tufted material. The sealing material may have a surface resistivity in the range from 1×105 Ω/sq to 1×1012 Ω/sq. 
     The bristles may comprise carbon fibre bristles. The carbon fibre bristles may have a stiffness which is greater than the stiffness of the sealing material in a radial direction. 
     The carbon fibre bristles may have a surface resistivity between 1×103 Ω/sq and 1×106 Ω/sq. The selection of material having a surface resistivity in this range can ensure that any static electricity on the floor surface is effectively discharged by the second agitating means. Values of surface resistivity discussed herein are as measured using the test method ASTM D257. 
     The diameter of each bristle may be not greater than 10 μm. The bristles may be arranged in a plurality of rows extending longitudinally with respect to the brush bar. The width of each row may be not greater than 5 mm, for example not greater than 2 mm. The rows of bristles may be arranged in a generally helical configuration extending around, or partially around, the brush bar. 
     The bristle density of the bristles is not less than 10,000 bristles per 10 mm in length. A bristle density of not less than 10,000 bristles is particularly effective because it provides effective sealing of the brush bar against the housing. A brush bar comprising rows of bristles having widths less than 2 mm and bristle densities greater than 10,000 are expected to provide excellent sealing characteristics and fine dust pick-up performance. The length of each bristle may be between 4 mm and 8 mm. 
     In particular, a brush bar comprising carbon fibre bristles having a diameters which are not greater than 10 μm and lengths which are between 4 mm and 8 mm and which are arranged in rows having a bristle density which is not less than 10,000 bristles per 10 mm is expected to be particularly effective at picking up dirt and dust from hard surfaces. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In order to better understand the present invention, and to show more clearly how the invention may be put into effect, the invention will now be described, by way of example, with reference to the following drawings: 
         FIG. 1  is a perspective view of a hand-held vacuum cleaner; 
         FIG. 2  is a perspective view of the cleaner head of the vacuum cleaner shown in  FIG. 1 ; 
         FIG. 3  is a front view of the cleaner head shown in  FIG. 2 ; 
         FIG. 4  is a side view of the cleaner head shown in  FIG. 2 ; 
         FIG. 5  is a rear view of the cleaner head shown in  FIG. 2 ; 
         FIG. 6  is an underside view of the cleaner head shown in  FIG. 2 ; and 
         FIG. 7  is a sectional view in the transverse direction of the cleaner head shown in  FIG. 2 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  shows a hand-held vacuum cleaner  2  comprising a main body  4 , a wand  6  and a cleaner head  8 . 
     The main body  4  comprises a separating system  10 , in the form of a cyclonic separator, a motor and impeller (not visible) arranged to draw air through the separating system  10 , and a power supply  12 , in the form of a battery, for powering the motor. The main body  4  has a handle  14  which is gripped by a user, and a clean air outlet  16  through which air that has passed through the separating system  10  is discharged. 
     The wand  6  is attached at one end to the main body  4  and at the other end to the cleaner head  8 . The wand  6  provides fluid communication between the cleaner head  8  and the separating system  10 , and supports the cleaner head  8  during use. 
       FIGS. 2 to 7  show the cleaner head  8  in isolation. The cleaner head  8  comprises an agitator in the form of a brush bar  18 , a rear roller  20 , and a housing  22  which defines a chamber  24  within which the brush bar  18  and the rear roller  20  are at least partially disposed. 
     The housing  22  is connected to the wand  6  by a pivoting arrangement  26  comprising upper and lower pivotal joints  28 ,  30  which enable the cleaner head  8  to be pivoted in yaw and pitch with respect to the wand  6 . A flexible hose  32  extends from a connecting portion  34  of the pivoting arrangement  26  into an upper region of the chamber  24 . The end of the hose  32  that extends into the chamber  24  defines a dirty air outlet  36  (shown in  FIGS. 6 and 7 ) from the chamber  24  through which air is drawn into the wand  6  and through the separating system  10 . 
     The brush bar  18  and the rear roller  20  are supported at each of their respective ends by side walls  38 ,  40  of the housing  22 . The brush bar  18  and the rear roller  20  are each rotatably supported by the side walls  38 ,  40  so that they can rotate with respect to the housing  22 . 
     With reference to  FIG. 7 , the brush bar  18  comprises a core  42  in the form of a rigid tube within which a brush bar motor (not shown) and a transmission  44  are disposed. The motor and the transmission  44  are arranged to drive the brush bar  18 . The brush bar  18  comprises four bristle strips  46 , also known as “starts”, spaced circumferentially about the core  42 . The bristle strips  46  are spaced apart from each other by the same separation angle (i.e. 90 degrees). Each bristle strip  46  comprises a row of radially extending bristles which are held by a locating strip  48 . The bristles may be densely packed, or spaced apart either in clumps or individually. 
     Each bristle strip  46  extends both longitudinally and circumferentially with respect to the brush bar  18  in a generally helical configuration. Each bristle strip  46  extends circumferentially through an angle of 90 degrees over the length of the brush bar  18 . The locating strip  48  of each bristle strip  46  is secured to the core  42  within a corresponding groove  50  provided in the outer surface of the core  42 . Each groove  50  has opposing lips along each edge of the groove  50  which interlock with the locating strip  48  to secure the bristle strip  46  to the core  42 . 
     Strips of a sealing material  52  are secured to the outer surface of the core  42  between the bristle strips  46 . The sealing material is locally deformable so that debris pressed into the material is at least partially enveloped by the material. The sealing material may also be resilient so that once debris has been extracted, the material returns to a nominal shape. However, it will be appreciated that centrifugal forces acting on the brush bar  18  during use may return the sealing material to its nominal shape. 
     In the embodiment shown, the sealing material is a tufted material. The material may, for example, be a tufted material having a short dense pile and may be formed by filaments woven to a fabric substrate. The filaments of the pile may be made from nylon, or other suitable material having a relatively low stiffness. The stiffness of a tufted sealing material will depend on the elastic properties of the material, the filament diameter, filament length and pile density. In the embodiment shown, the tufted material is made from nylon and has a filament diameter of between 30 μm and 50 μm (preferably 30 μm), a filament length of 0.005 m and a pile density of 60,000 filaments/25 mm2. The sealing material need not be a tufted material, but could be a foam material such as a closed cell foam material or other suitable material that provides adequate flow restriction. It will be appreciated that although a deformable sealing material is preferred, this is not essential. 
     There are four strips of sealing material  52  in total. The thickness (i.e. radial depth) of each strip of sealing material  52  is substantially constant, and the sealing strips  52  are substantially identical. 
     Each strip of sealing material  52  extends over substantially the entire radial and axial extent of the outer surface of the rigid tube  42  between adjacent bristle strips  46 . For example, each strip of sealing material  52  may extend over an angle of 75 to 90 degrees, preferably 80 to 90 degrees of the circumferential extent of the brush bar  18 . A gap  54  may be formed between one or more of the bristle strips  46  and an adjacent strip of sealing material  52 . In the embodiment shown, each strip of sealing material  52  extends over an angle of 80 degrees and each a gap  54  extending through an angle of 5 degrees is formed each side of each bristle strip  46  (reference signs are provided for the gaps  54  on opposite sides of only one of the bristle strips  46 ). The gaps  54  allow the bristle strips  46  to flex slightly without contacting the strips of sealing material  52 . It will be appreciated that the strips of sealing material  52  may abut the bristle strips  46  so that no gaps are provided between the strips of sealing material  52  and the bristles. This is expected to improve sealing effectiveness. 
     Fewer or more bristle strips  46  may be provided, in which case a corresponding number of strips of sealing material  52  are used. For example, two or three bristle strips  46  may be provided. 
     The radial extent of the bristle strips  46  is greater than the radial extent of the strips of sealing material  52 . That is, the radial distance between the tips of the bristle strips  46  and the rotational axis of the brush bar  18  is greater than the radial distance between the periphery of the strips of sealing material  52  and the rotational axis of the brush bar  18 . The radius of the brush bar  18  is defined as the distance between the axis of the brush bar  18  and the tips of the bristle strips  46 . 
     The bristles of the bristle strips  46  are preferably made from a material which is stiffer than the sealing material disposed between the bristle strips  38 . The bristle strips may comprise carbon fibre filaments having a thickness of between 5 μm and 10 μm, preferably 7 μm. In the embodiment shown, the carbon fibre filaments are 5.9 mm in length and the bristle density (i.e. the number of filaments per millimetre in length of the bristle strips  38 ) of the bristle strips  38  is 12,000 bristles per 10 mm. The bristles are arranged in bundles that are spaced apart from each other in the longitudinal direction of each bristle strip  38 . There are 6 bundles per 10 mm of the length of each bristle strip  38 . 
     The rear roller  20  comprises a core  56  in the form of a solid shaft wrapped in a strip of a tufted material. The tufted material may be the same as the tufted material of the brush bar  18 . 
     The underside of the housing  22  is open. In the embodiment shown, the housing  22  comprises a rear sole plate  58  (see  FIG. 6 ) which extends transversely with respect to the cleaner head  8  from one of the side walls  38 ,  40  of the housing  22  to the other. A support in the form of wheels  60  are supported by the sole plate  58 . The wheels  60  are set into the sole plate  58  so that only a lower portion of each wheel  60  protrudes from the sole plate  58 . 
     Each side wall  38 ,  40  has a lower edge  62 ,  64 . The sole plate  28  has a leading edge  66 , which is a working edge, that extends from one of the lower edges  62 ,  64  to the other. The lower edges  62 ,  64  of the side walls  38 ,  40  and the leading edge  66  of the sole plate  58  together define the side and rear peripheral edge of a dirty air inlet  68  of the chamber  24 . 
     The forward peripheral edge of the dirty air inlet  68  is defined by the brush bar  18 . In particular, the forward periphery of the dirty air inlet  68  is defined by the lowermost radial periphery of the strips of sealing material  52 . 
     The wheels  60  support the cleaner head  8  on a surface being cleaned such that the sole plate  58 , the side walls  38 ,  40  and the strips of sealing material  52  are spaced from the surface. In the embodiment shown, the brush bar  18  is arranged such that strips of sealing material  52  are spaced from the surface being cleaned by an amount that provides clearance of the strips of sealing material  52  from the surface, but which does not impair the sealing effectiveness between the strips of sealing material  52  and the surface. 
     The sole plate  58  and the side walls  38 ,  40  are spaced further from the surface being cleaned than the strips of sealing material  52 . A rear sealing strip  70  is therefore provided along the underside of the sole plate  58  adjacent the leading edge  66 . Side sealing strips  71 ,  72  are also provided along the lower edges  62 ,  64  of the side walls  38 ,  40 . The sealing strips  70 ,  71 ,  72  are arranged to seal against the surface being cleaned during use. The sealing strips  70 ,  71 ,  72  comprise a material having a pile, for example a tufted fabric/brush-like fabric having filaments made of a suitable material, such as nylon. 
     The housing  22  has an upper front edge  74  which extends transversely with respect to the cleaner head  8 . The upper front edge  74  is above the rotational axis of the brush bar  18  and below the top of the brush bar  18 . The brush bar  18  extends forwards of the upper front edge  74 . The upper front edge  74  and the front edges  75 ,  77  (shown in  FIGS. 3 and 4 ) of the side walls  38 ,  40  define a front opening of the chamber  24 . 
     The inner surface of a front region of the housing  22  which defines part of the chamber  24  curves over the top of the brush bar  18 . The radius of curvature of the inner surface of the chamber  24  corresponds to the radius of the tips of the bristle strips  46 . The front region of the housing  22  adjacent the front edge  74  provides a guard which prevents debris from being flung upwardly and/or forwardly by the brush bar  18  during use. However, it will be appreciated that in alternative embodiments the housing need not be arranged as a guard and need not extend forwardly of the top of the brush bar  18 . It will be appreciated that a small clearance may be provided to prevent interference between the tips of the bristles and the housing  22 . The brush bar  18  is arranged so that the sealing material restricts flow between the brush bar  18  and the inner surface of the housing adjacent the front edge  74 . 
     A partition  76  is arranged within the chamber  24  between the brush bar  18  and the chamber outlet  36 . The partition  76  extends transversely with respect to the cleaner head  8  and divides the chamber  24  into a settling region  24   a , between the partition  76  and the chamber outlet  36 , and an agitating region  24   b , forward of the partition  76 . 
     The partition  76  comprises a front wall  78  and a rear wall  80  which extend across the chamber  24 . The front wall  78  is supported at each end by the side walls  38 ,  40  of the housing  22 . The front wall  78  extends in a plane which is substantially tangential to the brush bar  18 , and inclined rearwardly with respect to the upright direction of the cleaner head  8 . The front wall  78  has a lower edge  82  and an upper edge  84  which extend along the length of the front wall  78 . The lower edge  82  and the sidewalls  38 ,  40  define a first debris opening  86  beneath the front wall  78  in the form of a slot. The first debris opening  86  extends in a direction which is parallel with the rotational axis of the brush bar  18 . 
     The rear wall  80  is disposed between the front wall  78  and the chamber outlet  36 , and extends downwardly from an upper region of the chamber  24  in a direction which is substantially parallel with the front wall  78 . 
     The rear wall  80  has a joining portion  88  which abuts the housing  22 . The joining portion  88  has a front edge  90 . The upper edge  84  of the front wall  78  and the front edge  90  of the joining portion  88  define a second debris opening  92  in the form of a slot. The second debris opening  92  extends in a direction which is parallel with the rotational axis of the brush bar  18 . The front edge  90  is substantially level with the rotational axis of the brush bar  18  and forms a lip that overhangs the upper edge  84  of the front wall  78  (i.e. the front edge  90  projects radially inwardly of the upper edge  84  with respect to the rotational axis of the brush bar  18 ). 
     The front wall  78  and the rear wall  80  define a debris recovery passageway which extends downwardly and forwardly from the second debris opening  92 . The passageway opens at the lower end into the settling region  24   a  of the chamber  24 . A portion of the joining portion  88  between the rear wall  80  and the front edge  90  has an inclined front surface  94  which is inclined forwardly at an angle of between 35 degrees and 65 degrees to the upright direction of cleaner head  8 . The inclined front surface  94  forms a deflector for deflecting debris downwardly along the passageway defined by the front and rear walls  78 ,  80 . 
     In use, the cleaner head  8  of the vacuum cleaner  2  is placed on a floor, for example a floor having a hard surface. The cleaner head  8  is supported on the surface by the rollers  60  so that the sealing strips  70 ,  71 ,  72 , together with the lower periphery of the sealing material of the brush bar  18 , seal against the surface being cleaned. The chamber  24  is therefore sealed around the periphery of the dirty air inlet  68  by the sealing strips  70 ,  71 ,  72  and the sealing material  52  of the brush bar  18 . In addition, the brush bar  18  seals against the upper inner surface of the housing  22  adjacent the front edge  74 . 
     In the context of the specification, the term “seal” should be understood to mean capable of maintaining a predetermined pressure difference during use of the vacuum cleaner  2 . For example, the chamber  24  can be regarded as being sealed provided that the flow of air through the chamber  24  is restricted to an amount that is sufficient to maintain a pressure difference of at least 0.65 kPa between the inside of chamber  24  and ambient during normal use (e.g. when used to clean a hard/firm surface). Similarly, the brush bar  18  can be considered to be sealed against the housing  22  if the flow of air through the front opening is restricted by the brush bar  18  such that a pressure difference of at least 0.65 kPa between the inside of chamber  24  and ambient is maintained during normal use. 
     The motor and the impeller draw air into the chamber  24  through the dirty air inlet  68  in the housing  22  and upwardly through the chamber outlet  36 , through the wand  6  and into the separating system  10 . Dirt is extracted from the air by the separating system  10  before being exhausted through the clean air outlet  16 . 
     The brush bar  18  is driven in a forward direction which is the counter-clockwise direction in  FIG. 7 . The brush bar  18  is driven at a relatively high rotational speed, for example between 600 rpm and 3000 rpm, preferably between 600 rpm and 1400 rpm. Increasing the rotational speed can be expected to improve fine dust pick up performance. The boundary layer effect in the vicinity of the sealing material  52  and the bristle strips  46  causes rotational flow within the agitating region  24   b  of the chamber  24  in the direction of rotation of the brush bar  18 . The rotational flow dynamically seals the gap between the brush bar  18  and the front edge  74  of the housing  22 . This dynamic sealing of the chamber  24  helps to maintain pressure within the chamber  24  by further restricting flow of air between the brush bar  18  and the housing  22 . 
     As the cleaner head  8  is moved across the surface being cleaned, the tips of the bristles of the bristle strips  46  contact the surface and sweep debris rearwardly towards the first debris opening  86 . The bristles are particularly effective at removing fine dust from crevices and agitating dust that has been compacted on the surface being cleaned. The gaps  54  extending along each side of the bristle strips  46  accommodate flexing of the bristles as they are pressed against the surface of the floor. 
     As the cleaner head  8  is moved over large debris (i.e. debris that is larger than the clearance between the periphery of the sealing material  52  and the floor), for example grains of rice, oats, pasta, cereals or similar, the sealing material  52  is deformed locally by the debris. 
     Local deformation of the sealing material  52  ensures that, for most large debris, the cleaner head  8  does not ride-up over the debris, which would reduce sealing effectiveness between the sealing strip  70 ,  71 ,  72 , the sealing material  52  on the brush bar  18  and the floor surface. Sealing between the brush bar  18  and the surface being cleaned is therefore not adversely affected, and so effective pick-up performance is maintained. The large debris, which has been substantially enveloped by the sealing material  52 , is then released rearwardly through the first debris opening  86  into the settling region  24   a  of the chamber  24 . Smaller debris or debris which clings to the floor, such as compacted dust, is agitated by the bristle strips  46  and swept rearwardly through the first debris opening  86  into the settling region  24   a  of the chamber  24 . The debris, as well as other debris which may have been drawn directly up through the dirty air inlet  68 , is sucked through the chamber outlet  36  to the separating system  10 , as described above. 
     It will be appreciated that the sealing material  52  also deforms to accommodate small variations in the surface being cleaned without causing scratching of the surface. 
     In some circumstances, debris having relatively high inertia such as large debris, for example rice or large dust particles, rebounds off the rear wall of the settling region  24   a  of the chamber  24  back though the first debris opening  86  without being sucked up through the chamber outlet  36 . Such debris collides with the brush bar  18  and is swept either back through the first debris opening  86  or else is driven upwardly along the front surface of the front wall  78  of the partition  76  towards the second debris opening  92 . The overhanging front edge  90  intercepts the debris and directs the debris rearwardly towards the inclined front surface  94  of the joining portion  88 . The overhanging front edge  90  therefore prevents the debris from being swept along the inner surface of the chamber  24  and out through the front opening by the brush bar  18 . 
     Debris which collides with the inclined front surface  94  is directed downwardly along the passageway between the front and rear walls  78 ,  80  of the partition  76  into the settling region  24   a  of the chamber  24 . Each collision of the debris with the front and rear walls  78 ,  80  dissipates some of the kinetic energy of the debris, thereby reducing its inertia. Consequently, debris that falls down along the passageway into the settling region  24   a  is entrained by the air flowing through the chamber  24  and sucked the chamber outlet  36  to the separating system  10 . 
     The front opening of the housing  22  allows the brush bar  18  to be pushed up against an object on the surface being cleaned or against a wall so the brush bar can pick up debris adjacent the object or wall. This improves overall pick up performance. 
     The rear roller  20  is arranged to roll of debris on the surface being cleaned. Therefore, debris is not scraped along the surface being cleaned which could otherwise scratch the surface. 
     The cleaner head  8  is effective at picking up both small and large debris as well as dust that has been compacted. The cleaner head  8  is particularly effective on hard floors in which large debris stands proud of the surface, or on which dust has been compacted.