Abstract:
A reciprocating work head for use with an electric tool assembly, such as an electric brush, comprises a movable section and a fixed section. The movable section carries a retaining pin. The movable section is arranged to move along the retaining pin in a reciprocating motion along the longitudinal axis of the fixed section. There is also disclosed an electric tool assembly, such as an electric brush, comprising such a work head.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to a replaceable reciprocating work head, for example a brush head for use in an electric tool assembly such as an electric brush assembly.  
       BACKGROUND OF THE INVENTION  
       [0002]     It is often desirable to remove small dirt patches and spots from fabrics such as carpets and this is often conventionally carried out manually using a scrubbing brush or using a vacuum cleaner with a brush attachment. Manual scrubbing may be labour intensive and once the bristles on the brush have worn down the brush must be discarded. The use of a conventional vacuum cleaner may be difficult in some circumstances as the vacuum cleaner is a generally cumbersome device and not suitable for use in all locations.  
         [0003]     Thus there is a need for a low cost modular replaceable reciprocating work head such as a brush head for use in an electric tool, such as a brush, of small size.  
       SUMMARY OF THE INVENTION  
       [0004]     According to a first aspect of the invention there is provided a reciprocating work head for use with an electric tool assembly comprising:  
         [0005]     a movable section; and  
         [0006]     a fixed section having a longitudinal axis, the movable section carrying a retaining pin;  
         [0000]     wherein the movable section is arranged to move along the retaining pin in a reciprocating motion along the longitudinal axis of the fixed section.  
         [0007]     According to a further aspect there is provided an electric brush assembly comprising the reciprocating work head defined above. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]     Preferred features of the invention will now be described, for the sake of illustration only, with reference to the following figures in which:  
         [0009]      FIG. 1   a  is a plan view showing the bristle side of a brush head according to a first preferred embodiment of the invention;  
         [0010]      FIG. 1   b  is an elevation of the brush head according to  FIG. 1   a;    
         [0011]      FIG. 1   c  is a plan view of the other side of the brush head to that shown in  FIG. 1   a;    
         [0012]      FIG. 2  is a parts exploded view of the brush head of  FIGS. 1   a  to  c  showing the assembly method;  
         [0013]      FIG. 3  is a cross-sectional view through the brush head of  FIGS. 1   a  to  c;    
         [0014]      FIG. 4  is a sectional view through a longitudinal centreline of the brush head of  FIG. 3 ;  
         [0015]      FIG. 5   a  is a perspective view of the bristle side of a brush head having bristles at one extreme position according to a first preferred embodiment of the invention;  
         [0016]      FIG. 5   b  is a perspective view of the other side of the brush head of  FIG. 5   a  in the same position as that shown in  FIG. 5   a;    
         [0017]      FIG. 6   a  is a perspective view of a bristle side of a brush head with bristles at another extreme position;  
         [0018]      FIG. 6   b  is a perspective view of the other side of the brush head of  FIG. 6   a  in the same position as the brush head of  FIG. 6   a;    
         [0019]      FIG. 7   a  is a projection showing the underside (non-bristle side) of the brush head attached to a brush drive assembly; and  
         [0020]      FIG. 7   b  is a projection showing the upperside (bristle side) of a brush drive assembly with the brush head removed from the brush drive assembly. 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0021]      FIG. 1   a  shows a brush head  1  according to a first preferred embodiment of the invention. The brush head  1  comprises a reciprocating bristle block section  2  mounted in a stationary bristle block section  4 , and a finger-release tab  6  attached to the stationary bristle block section  4  for removing the brush head  1  from a brush body (not shown) to which it may be attached.  
         [0022]      FIG. 1   b  shows an elevation of the brush head  1  of  FIG. 1   a  with the two bristle block sections  2 ,  4  assembled together. The stationary bristle block section  4  has a first face  8  through which a plurality of bristles  10  extend and a second face  11  extending in a plane substantially parallel to the first face  8 . Two substantially parallel projections  12  are mounted on the second face  11  and extend along the face  11  in a plane substantially parallel thereto. The projections  12  are undercut  13  on their respective faces to engage with flanges in the housing of the brush assembly thereby retaining the brush head  1  on the assembly. The reciprocating bristle block section  2  also has a plurality of bristles extending through apertures in a face of thereof.  
         [0023]      FIG. 1   c  shows a plan view of the non-bristle side of the assembled brush head  1  of  FIGS. 1   a  and  b . A drive lug  14  is mounted on to the face opposing the bristle face of the reciprocating bristle block section  2  and projects through a slot  15  in the stationary bristle block section  4 . A guide and retaining pin  16 , which is preferably formed of stainless steel, passes through the drive lug  14  and is retained in the body of the stationary bristle block section  4 . The pin  16  has a longitudinal axis which extends substantially parallel to the axis of motion of the reciprocating bristle block section  2 . the pin  16  serves to retain the reciprocating bristle block section  2  in place on the drive mechanism and to guide it in its reciprocating motion.  
         [0024]      FIG. 2  shows a parts exploded view of the brush head  1  according to a first preferred embodiment, and illustrates the assembly method. The reciprocating bristle block section  2  (shown here without its bristles) slides along the first face  8  of the stationary bristle block section  4  (also shown here without its bristles) and the drive lug  14  on the face of the reciprocating bristle block section  2  opposing the face through which the bristles extend is mounted through the slot  15  in the stationary bristle block section  4 . The guide pin  16  is inserted into the stationary bristle block section  4  and passes through the drive lug  14  on the reciprocating bristle block section  2  so that the pin  16  is retained at both ends in the stationary bristle block section  4  and the reciprocating bristle block section  2  is able to slide on the pin  16  when moved by the drive mechanism along the longitudinal axis of the stationary bristle block section  4 .  
         [0025]     The head of the brush assembly is mountable in use on a body (not shown) and is retained by flanges on the body engaging with the undercut surfaces  13  of the projections  12  on the second face  11  of the stationary bristle block section  4 .  
         [0026]      FIG. 3  shows a section through an assembled brush head  1  along the axis of motion. The reciprocating bristle block section  2  (shown here without its bristles) is mounted on the first face  8  of the stationary bristle block section  4  with its drive lug  14  passing through the slot  15  in the stationary bristle block section  4  (which is also shown here without its bristles). The guide and retaining pin  16  is inserted along the axis of the brush head  1  and passes through the stationary bristle block section  4 , through the drive lug  14  of the reciprocating bristle block section  2  and into the stationary bristle block section  4  at the other end of the slot  15  therein. The drive lug  14  is a sliding fit on the guide pin  16 .  
         [0027]     The reciprocating bristle block section  2  and/or the stationary bristle block section  4  may formed of polyoxymethylene (POM) plastic which is advantageous as it does not require lubrication which could stain the fabric to be cleaned using the brush assembly.  
         [0028]      FIG. 4  shows a projected view sectioned along the central longitudinal axis of the guide pin  16 . The reciprocating bristle block section  2  slides on the first face  8  of the stationary bristle block section  4  with its drive lug  14  projecting through a slot  15  in the stationary bristle block section  4 . The guide pin  16  extends through an aperture in the stationary bristle block section  4 , across the slot  15  therein, and passes through the drive lug  14  in the process  
         [0029]      FIG. 5   a  shows a projection view of a first face of the brush head  1  with the reciprocating bristle block section  2  at one extreme position of its travel, that is, at the end furthest from the finger release tab  6 . The bristles  10  on the stationary bristle block section  4  are preferably longer than those on the reciprocating bristle block section  2 .  
         [0030]      FIG. 5   b  is a projection view of the second face of the brush head  1  with the reciprocating bristle block section  2  still at its extreme point of travel furthest from the finger release tab  6 .  
         [0031]      FIG. 6   a  shows a projection view of the first face of the brush head  1  with the reciprocating bristle block section  2  at the other extreme position of its travel to that shown in  FIGS. 5   a  and  b , that is, at the end closest to the finger release tab  6 .  
         [0032]      FIG. 6   b  is a projection view of the second face of the brush head  1  with the reciprocating bristle block section  2  still at its extreme point of travel closest to the finger release tab  6 .  
         [0033]      FIG. 7   a  shows the one side of the brush head  1  attached to a body  20  of a brush assembly  22  and  FIG. 7   b  shows the other side of the brush assembly  22  with the brush head  1  removed from the brush assembly  22 .  
         [0034]     The brush head may preferably be used as part of an electrically driven brush, for example for cleaning fabrics such as carpets and may be used for cleaning other fabrics. In such a configuration, it comprises the two bristle block sections  2 ,  4  each containing a plurality of bristles  10 , an outer set  10  projecting through the stationary bristle block section  4  which does not move in use with respect to the drive assembly and an inner set extending through the reciprocating bristle block section  2  which is arranged to reciprocate along the axis of the device. The stationary bristles  10  may preferably be slightly longer than the moving ones and would thus tend to take the higher loading when the brush head  1  is pressed against the fabric/surface to be cleaned thereby reducing motor loading and increasing battery life.  
         [0035]     The outer bristles  10  brush against the fabric due to the natural hand motion of the user and thus combine with the reciprocating bristles to assist in the cleaning process.  
         [0036]     The brush head  1  is a complete module in itself and may be clipped on and off the brush body  20  manually and without tools.  
         [0037]     When replacing the brush head  1 , it is not necessary to align the drive lug  14  with the drive mechanism as this will align automatically as it is pressed home.  
         [0038]     Various modifications to the embodiments of the present invention described above may be made. For example, whilst embodiments of the present invention have been described and illustrated herein in the context of an electric brush assembly and a brush head therefor, the present invention is not to be considered limited thereto as it is applicable for use in the context of other forms of electric tool assemblies. Also, other components, materials and method steps may be added or substituted for those described above. Thus, although the invention has been described using particular embodiments, many variations are possible within the scope of the claims, as will be clear to the skilled reader, without departing from the spirit and scope of the invention.