Abstract:
A cyclonic separating apparatus for separating particles from a dirt-laden airflow includes a cyclone for separating and collecting dirt and dust from the dirt-laden airflow. The cyclone has an air inlet, an air outlet, a longitudinal axis and a wall. The wall includes a first portion and a second portion spaced farther from the longitudinal axis than the first portion, the first and second portions being spaced along the longitudinal axis. The cyclone also includes at least one lip extending from the first portion of the wall into a portion of the cyclone surrounded by the second portion of the wall. By providing a cyclone with a wall having two portions of different sizes and a lip extending from the portion with the smaller size into the portion with the larger size, the risk of blockages due to re-entrainment and movement of dirt and dust within the cyclonic separating apparatus is reduced.

Description:
REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a national stage application under 35 USC 371 of International Application No. PCT/GB2007/002525, filed Jul. 6, 2007, which claims the priority of United Kingdom Application No. 0614237.6, filed Jul. 18, 2006, the contents of which prior applications are incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention relates to cyclonic separating apparatus particularly, but not exclusively, for a vacuum cleaner. More particularly, the invention relates to cyclonic separating apparatus for a hand-held vacuum cleaner. 
       BACKGROUND OF THE INVENTION 
       [0003]    Cyclonic separating apparatus is known from, for example, EP 0 042 723. This document discloses a vacuum cleaner which separates particles from an airflow using two reverse flow cyclones. The cyclones comprise a first, low-efficiency cyclone and a second, high-efficiency cyclone downstream of the first cyclone. Dirt- and dust-laden air enters through an inlet in the first cyclone and follows a downward helical path around the interior of the first cyclone. Centrifugal forces act on the entrained dirt and dust to separate it from the airflow. When separated from the airflow, the dirt and dust collects at the base of the first cyclone. Upon reaching the base of the first cyclone, the airflow reverses direction. The partially-cleaned airflow moves back up the first cyclone and exits the first cyclone through an outlet. It is usual to provide a so-called shroud around the outlet from the first cyclone. The shroud comprises a wall with a large number of through-holes through which the airflow passes in order to reach the second cyclone. The air then enters the second cyclone and follows a downward helical path inside the second cyclone. Smaller particles are separated from the airflow in a similar fashion to the first cyclone and are deposited in a collector located beneath the second cyclone. The cleaned air then flows back up the interior of the second cyclone and passes sequentially through a pre-motor filter, a motor and a post-motor filter before being exhausted from the vacuum cleaner. 
         [0004]    Occasionally, in this arrangement, some of the dirt and dust which has been separated from the airflow becomes re-entrained in the return airflow. This is undesirable because this dirt and dust may cause blockages in parts of the cyclonic separating apparatus such as the through-holes of the shroud. Blocking the through-holes of the shroud will reduce the efficiency at which the cyclonic separating apparatus operates. 
         [0005]    In order to improve the retention of dirt and dust in the first cyclone upstream of the shroud, it is known to provide the shroud with a lip projecting into the first cyclone. An example of such a lip is shown and described in EP 0 800 359. This lip reduces the risk of the shroud through-holes becoming clogged or blocked. 
         [0006]    However, whilst this solution is useful for cyclonic separating apparatus which is orientated substantially vertically (such as in an upright machine), this arrangement may be less effective for cyclonic separating apparatus which is orientated away from the vertical. Such a situation may arise when, for example, the cyclonic separating apparatus is arranged at an angle to the vertical in a cylinder machine or forms part of a hand-held vacuum cleaner which may be held at an arbitrary angle by a user. In these circumstances, there is a risk that the separated dirt and dust will move towards the outlet of the first cyclone. This is undesirable because the dirt and dust may block the inlet or the through-holes in the shroud. 
         [0007]    It is known to provide an inwardly-extending projection on the wall of a cyclone. EP 0 728 435 and GB 2 363 744 both show an inwardly-projecting annular collar or rib located around the lower part of the inner surface of such a cyclone. In both of these prior art disclosures, it is suggested that these features will help to prevent dirt and dust becoming re-entrained in the partially-cleaned airflow. However, the introduction of elements such as inwardly-projecting ribs or collars on the inner wall of a cyclone may also introduce unwanted effects. For example, these elements may generate turbulence within the cyclone which may disturb the deposited dirt and dust in an undesirable way. Further, the introduction of these elements can reduce the separation efficiency of the cyclone. 
       SUMMARY OF THE INVENTION 
       [0008]    It is an object of the present invention to provide cyclonic separating apparatus which reduces the risk of re-entrainment of dirt and dust separated from an airflow whilst minimising any detrimental effect on the separation efficiency of the cyclonic separating apparatus. It is a further object to provide cyclonic separating apparatus which minimises the risk of re-entrainment of dirt and dust separated from an airflow when the cyclonic separating apparatus is moved away from a vertical orientation. 
         [0009]    The invention provides cyclonic separating apparatus for separating particles from a dirt- and dust-laden airflow comprising a cyclone for separating and collecting dirt and dust from the dirt- and dust-laden airflow, the cyclone having an air inlet, an air outlet, a longitudinal axis and a wall, the wall comprising a first portion and a second portion spaced further from the longitudinal axis than the first portion, the first and second portions being axially spaced along the longitudinal axis, wherein the cyclone further comprises at least one lip extending from the first portion of the wall into a portion of the cyclone surrounded by the second portion of the wall. By providing a cyclone with a wall having two portions of different sizes and a lip extending from the smaller portion into the larger portion, the risk of blockages due to re-entrainment and movement of dirt and dust within the cyclonic separating apparatus is reduced. 
         [0010]    Preferably, the first portion of the cyclone is cylindrical and has a first radius. More preferably, at least a part of the second portion of the cyclone is cylindrical and has a second radius. 
         [0011]    Preferably, the lip forms a substantially straight extension of the first portion of the wall. This arrangement minimises the protrusion of the lip into the airflow whilst still reducing the risk of re-entrainment of separated dirt and dust within the cyclonic separating apparatus. 
         [0012]    Preferably, the cyclonic separating apparatus comprises at least one further cyclone and a collector which are located downstream of the air outlet, the at least one further cyclone being arranged to deposit separated dirt and dust into the collector. More preferably, the collector has a longitudinal axis, a wall and at least one further lip extending from the wall of the collector into the collector. By providing a lip extending from the wall of the collector, the risk of re-entrainment and migration of fine dirt and dust deposited in the collector can be minimised and thus the risk of the further cyclones becoming blocked is reduced. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    Embodiments of the invention will now be described with reference to the accompanying drawings, in which: 
           [0014]      FIG. 1  shows a hand-held vacuum cleaner incorporating cyclonic separating apparatus according to a first embodiment of the invention; 
           [0015]      FIG. 2  is a cross section through the cyclonic separating apparatus of the hand-held vacuum cleaner of  FIG. 1  taken along a longitudinal axis thereof; 
           [0016]      FIG. 3  is a lateral cross section through the cyclonic separating apparatus of the hand-held vacuum cleaner of  FIG. 1 ; and 
           [0017]      FIGS. 4 to 11  are schematic diagrams of alternative embodiments of part of the cyclonic separating apparatus according to the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0018]      FIG. 1  shows a hand-held vacuum cleaner  10 . The hand-held vacuum cleaner  10  has a main body  12  which houses a motor and fan unit (not shown). The main body  12  also includes a power source  14  such as a battery. A handle  16  is provided on the main body  12  for manipulating the hand-held vacuum cleaner  10  in use. Cyclonic separating apparatus  100  is attached to the main body  12 . An inlet pipe  18  extends from a portion of the cyclonic separating apparatus  100  remote from the main body  12 . A dirty air inlet  20  is formed at the distal end of the inlet pipe  18 . A brush tool  22  is slidably mounted on the distal end of the inlet pipe  18 . A set of exhaust vents  24  are provided on the main body  12  for exhausting air from the hand-held vacuum cleaner  10 . 
         [0019]    The cyclonic separating apparatus  100  forming part of the hand-held vacuum cleaner  10  is shown in more detail in  FIGS. 2 and 3 . The cyclonic separating apparatus  100  comprises a cyclone  102  which has a longitudinal axis X-X and a wall  104 . The wall  104  comprises a first portion  106  and a second portion  108 . An inlet  110  is formed in the wall  104  and arranged so that the first portion  106  of the wall  104  is located between the inlet  110  and the second portion  108  of the wall  104 . The inlet  110  is in communication with the dirty air inlet  20  and forms a communication path between the inlet pipe  18  and the interior of the cyclone  102 . The air inlet  110  is arranged tangentially to the cyclone  102  so that the incoming air is forced to follow a helical path around the interior of the cyclone  102 . 
         [0020]    The first portion  106  of the wall  104  is substantially cylindrical and is in two parts. This is so that the parts can be separated to allow cleaning of the interior of the cyclone  102 . However, this is not material to the invention. The second portion  108  of the wall  104  is spaced further from the longitudinal axis X-X than the first portion  106  of the wall  104 . The second portion  108  of the wall  104  includes a shoulder  112  and a cylindrical part  113 . A lip  114  extends from the first portion  106  of the wall  104  into the space surrounded by the second portion  108  of the wall  104  of the cyclone  102 . The lip  114  forms a substantially straight extension of the first portion  106  of the wall  104 . The function of the lip  114  will be described later. 
         [0021]    A base  116  closes one end of the cyclone  102 . The base  116  is pivotably mounted on the lower end of the second portion  108  of the wall  104  by means of a hinge  118 . The base  116  is retained in a closed position (as shown in  FIGS. 1 to 3 ) by means of a catch  120 . 
         [0022]    A shroud  121  is located inwardly of the wall  104  of the cyclone  102 . The shroud  121  comprises a cylindrical wall  122  having a plurality of through-holes  123 . The shroud  121  surrounds an outlet  124  from the cyclone  102 . The outlet  124  provides a communication path between the cyclone  102  and a further cyclone assembly  126 . A lip  128  is provided at the base of the shroud  121 . The lip  128  has a plurality of through-holes which are designed to allow air to pass through but to capture dirt and dust. 
         [0023]    The further cyclone assembly  126  comprises a plurality of further cyclones  130  arranged in parallel. In this embodiment, six further cyclones  130  are provided. Each further cyclone  130  has a tangentially-arranged air inlet  132  and an air outlet  134 . Each air inlet  132  and air outlet  134  is located at a first end of the respective further cyclone  130 . A cone opening  136  is located at a second end of each further cyclone  130 . The cone opening  136  of each further cyclone  130  is inclined with respect to a longitudinal axis (not shown) of the respective further cyclone  130  as can be best seen in  FIG. 3 . The cone openings  136  of each of the further cyclones  130  are in communication with a passageway  138  defined by a wall  140  located inwardly of the shroud  121 . 
         [0024]    A collector  142  is located at the lower end of the passageway  138 . The collector  142  comprises a frustoconical first portion  144  and a cylindrical second portion  146 . The interior of the collector  142  is surrounded by the base  116  and the sides of the first and second portions  144 ,  146  of the collector  142 . 
         [0025]    A further lip  148  extends into the portion of the collector  142  surrounded by the cylindrical second portion  146 . The further lip  148  comprises a frustoconical portion  148   a  and a cylindrical portion  148   b  which extends substantially parallel to the sides of the second portion  146  of the collector  142 . The function of the further lip  148  will be described later. 
         [0026]    Each of the air outlets  134  of the further cyclones  130  is in communication with a duct  150 . The duct  150  provides an airflow path from the cyclonic separating apparatus  100  into other parts of the hand-held vacuum cleaner  10 . Located at the downstream end of the duct  150  is a pre-motor filter  152 . The pre-motor filter  152  comprises a porous material such as foam. 
         [0027]    In use, the motor and fan unit draws a flow of dirt-laden air into the dirty air inlet  20 , through the inlet pipe  18  and into the cyclonic separating apparatus  100 . Dirt-laden air enters the cyclonic separating apparatus  100  through the inlet  110 . Due to the tangential arrangement of the inlet  110 , the airflow is forced to follow a helical path around the interior of the wall  104 . Larger dirt and dust particles are separated by cyclonic motion around the wall  104 . These particles are then collected at the base  116  of the cyclone  102 . Separation of larger particles will occur in the region of the cyclone  102  surrounded by the first portion  106  of the wall  104  and also the portion of the cyclone  102  surrounded by the lip  114 . Separated particles gather in the portion of the cyclone  102  surrounded by the second portion  108  of the wall  104 . 
         [0028]    The partially-cleaned airflow then flows back up the interior of the cyclone  102  and exits the cyclone  102  via the through-holes in the shroud  121 . Once the airflow has passed through the shroud  121 , it enters the outlet  124  and from there is divided between the tangential inlets  132  of each of the further cyclones  130 . Each of the further cyclones  130  has a diameter smaller than that of the cyclone  102 . Therefore, the further cyclones  130  are able to separate smaller particles of dirt and dust from the partially-cleaned airflow than the cyclone  102 . Separated dirt and dust exits the further cyclones  130  via the cone openings  136 . Thereafter, the separated dirt and dust passes down the passageway  138  and into the collector  142 . The separated dirt and dust eventually settles at the base of the collector  142 . 
         [0029]    Cleaned air then flows back up the further cyclones  130 , exits the further cyclones  130  through the air outlets  134  and enters the duct  150 . The cleaned air then passes from the duct  150  sequentially through the pre-motor filter  152 , the motor and fan unit, and a post-motor filter before being exhausted from the vacuum cleaner  10  through the air vents  24 . 
         [0030]    It is likely that, in use, the hand-held vacuum cleaner  10  will be held in a variety of orientations. It may even be held upside down in use. When the cyclonic separating apparatus  100  is tilted away from the vertical, a large proportion of the separated dirt and dust that may otherwise move towards the inlet  110  and the shroud  121  is caught in an annular pocket created between the lip  114  and the second portion  108  of the wall  104 . Further, the presence of the above-described pocket may assist in the creation of stagnation points and eddy-currents within the lower portion of the cyclone  102 . This may further prevent re-entrainment of separated dirt and dust into the return airflow. 
         [0031]    Regarding the collector  142 , a pocket is created between the second portion  146  of the collector  142  and the further lip  148 . The pocket will prevent a proportion of the separated dirt and dust which may potentially block the cone openings  136  or other parts of the further cyclones  130  from re-entering the passageway  138  when the hand-held vacuum cleaner  10  is tilted away from the vertical. 
         [0032]    The cyclone  102  and collector  142  can be emptied simultaneously by releasing the catch  120  to allow the base  116  to pivot about the hinge  118  so that the separated dirt and dust can fall away from the cyclonic separating apparatus  100 . 
         [0033]    Both the lip  114  and the further lip  148  may take different configurations or shapes from those shown in the first embodiment.  FIGS. 4 to 11  illustrate schematically eight further alternative configurations of the lip or lips which fall within the scope of the invention. In these illustrations, all detail will be omitted other than the general shape of the lip and adjoining wall portions. These configurations of lip may be applied to either the lip in the cyclone or to the further lip in the collector. 
         [0034]      FIG. 4  shows a second embodiment of the invention. In this embodiment, the cyclonic separating apparatus  200  includes a lip  202  which extends from a first portion  204  of a wall into a region surrounded by a second portion  206  of the wall. The lip  202  has a plurality of through-holes which allow air to pass but block larger particles of dirt and dust. Otherwise, the lip  202  is the same as the lip  114  described above. 
         [0035]      FIG. 5  shows a third embodiment of the invention. In this embodiment, the cyclonic separating apparatus  250  includes a lip  252  which extends from a frustoconically-shaped first portion  254  of a wall into a region surrounded by a second portion  256  of the wall. The second portion  254  of the wall is partly frustoconical-shaped and partly cylindrical. 
         [0036]      FIG. 6  shows a fourth embodiment of the invention. In this embodiment (which is not shown to scale), the cyclonic separating apparatus  300  has a longitudinal axis X′-X′ and includes a lip  302  which extends from a cylindrically-shaped first portion  304  of a wall into a region surrounded by a second portion  306  of the wall. The lip  302  extends inwardly from the first portion  304  of the wall at an angle to the longitudinal axis X′-X′. 
         [0037]      FIG. 7  shows a fifth embodiment of the invention. In this embodiment (which is also not shown to scale), the cyclonic separating apparatus  350  has a longitudinal axis X″-X″ and includes a lip  352  which extends from a cylindrically-shaped first portion  354  of a wall into a region surrounded by a second portion  356  of the wall. The lip  352  extends outwardly from the first portion  304  of the wall at an angle to the longitudinal axis X″-X″. 
         [0038]      FIG. 8  shows a sixth embodiment of the invention. In this embodiment, the cyclonic separating apparatus  400  includes a lip  402  which extends from a cylindrically-shaped first portion  404  of a wall into a region surrounded by a second portion  406  of the wall. The lip  402  comprises two parts—a first part which forms a substantially straight extension of the first portion  404  of the wall and a second part which forms an inwardly-extending annular part at right angles to the first part. 
         [0039]      FIG. 9  shows a seventh embodiment of the invention. In this embodiment, the cyclonic separating apparatus  450  includes a lip  452  and first and second portions  454 ,  456  of a wall. This embodiment is the same as the sixth embodiment except that the annular part extends outwardly. 
         [0040]      FIG. 10  shows an eighth embodiment of the invention. In this embodiment, the cyclonic separating apparatus  500  includes a lip  502  extending from a cylindrically-shaped first portion  504  of a wall into a region surrounded by a second portion  506  of the wall. The lip  502  comprises two parts—a first part which extends inwardly and a second part which extends parallel to the first portion  504  of the wall. 
         [0041]      FIG. 11  shows a ninth embodiment of the invention. In this embodiment, the cyclonic separating apparatus  550  includes a first portion  552  of a wall which has a cylindrical part and an annular part. A lip  554  extends from the annular part of the first portion  552  into a region surrounded by a second portion  556  of the wall. 
         [0042]    The arrangements illustrated in  FIGS. 4 to 11  are intended to show that the number, shape and configuration of the lip or lips can be varied. It will be understood that other arrangements are also possible. For example, the further cyclone assembly may comprise any number of cyclones. Alternatively, the further cyclone assembly need not be present and a filter or other separating media may take its place. 
         [0043]    There need not be a collector or a lip on the collector. What is important is that there is one cyclone which has a wall with two portions of different sizes, and a lip extends from the smaller portion into the larger portion. 
         [0044]    The lips in the above-described embodiments all extend around the whole of the circumference of the wall of the cyclone. However, this need not be so. The lip may extend around only part of the circumference of the wall of the cyclone. Alternatively, a plurality of lips may be provided, each of which extends partly around the circumference of the wall of the cyclone. 
         [0045]    The lip may extend into a small part of the region surrounded by second portion of the wall of the cyclone or, alternatively, the lip may extend further into the cyclone. Any number of lips may be provided; for example, several concentric lips may be provided.