Patent Abstract:
A handheld cleaning appliance includes a dirty air inlet, a clean air outlet and separating apparatus for separating dirt and dust from an airflow in an airflow path leading from the air inlet to the air outlet. The separating apparatus includes a cyclonic separator having at least one first cyclone and a plurality of second cyclones arranged in parallel with one another and located downstream of the first cyclone. By providing a cyclonic separator having a plurality of second cyclones in parallel, the handheld cleaning appliance is capable of separating fine dirt and dust particles without using barriers such as filters or bags which need maintenance to ensure that performance remains high over a period of time.

Full Description:
REFERENCE TO RELATED APPLICATIONS 
     This application is a national stage application under 35 USC 371 of International Application No. PCT/GB2007/002529, filed Jul. 6, 2007, which claims the priority of United Kingdom Application Nos. 0614237.6 and 0618491.5, filed Jul. 18, 2006, and Sep. 20, 2006, respectively, the contents of which prior applications are incorporated herein by reference. 
     FIELD OF THE INVENTION 
     The invention relates to a handheld cleaning appliance particularly, but not exclusively, to a handheld vacuum cleaner. More particularly, the invention relates to a handheld cleaning appliance having a cyclonic separator. 
     BACKGROUND OF THE INVENTION 
     Handheld vacuum cleaners are well known and have been manufactured and sold by various manufacturers for several years. Typically, a handheld vacuum cleaner comprises a casing which houses a motor and fan unit for drawing air into the cleaner via an inlet, and a separation device such as a filter or bag for separating dirt and dust from the incoming airflow. An example of such a vacuum cleaner is shown in GB1207278. 
     Handheld vacuum cleaners have more recently been developed to incorporate cyclonic separation systems which are capable of removing larger items of debris from the airflow before removing finer particles using a filter or other barrier means. An example of such a device is sold by Black &amp; Decker under the trade name DUSTBUSTER®. A further example of a handheld vacuum cleaner incorporating a cyclonic separator is shown in GB2035787A. 
     A disadvantage of known handheld vacuum cleaners which utilise cyclonic separators is that, when only a single cyclone is used followed by a filter or bag, the filter will require maintenance, either by washing or by replacement. Failure to maintain the filter will result in a decrease in performance. It is therefore an object of the invention to provide a handheld cleaning appliance which is capable of sustaining high performance for longer than known handheld vacuum cleaners. It is a further object of the present invention to provide a handheld cleaning appliance which requires less maintenance than existing appliances. A further object of the present invention is to provide a handheld vacuum cleaner which is capable of developing and sustaining higher suction power than is possible with current designs of handheld vacuum cleaner. 
     SUMMARY OF THE INVENTION 
     The invention provides a handheld cleaning appliance comprising a dirty air inlet, a clean air outlet and separating apparatus located in an airflow path leading from the air inlet to the air outlet for separating dirt and dust from an airflow, the separating apparatus comprising a cyclonic separator having at least one first cyclone, wherein the cyclonic separator further comprises a plurality of second cyclones arranged in parallel with one another and located downstream of the or each first cyclone. 
     By providing a cyclonic separator which comprises a plurality of second cyclones in parallel, the handheld cleaning appliance becomes capable of separating fine dirt and dust particles without using barrier means such as filters or bags which need maintenance to ensure that performance remains high over a period of time. It has hitherto been considered difficult to provide a cyclonic separator of this type in a handheld vacuum cleaner because the space occupied by this type of cyclonic separator is considered to be too bulky and heavy to be suitable for a handheld machine. A further advantage of providing a cyclonic separator of this type in a handheld vacuum cleaner is that the cleaner is then capable of sustaining high suction power because there is no barrier-type filter means to cause a reduction in suction power, and hence pick-up capability, over time. 
     Preferably, the handheld cleaning appliance includes a handle and the cyclonic separator lies between the handle and the dirty air inlet. This provides an arrangement which is well balanced for a user of this type of cleaning appliance. 
     It is preferred that the cyclonic separator lies substantially parallel to the handle, and it is further preferred that the cyclonic separator lies in a generally upright configuration. These features have been found to be beneficial for manipulation and for convenient storage and emptying of the dirt and dust collected in the cyclonic separator. 
     In a preferred embodiment of the invention, a single first cyclone is provided and the second cyclones are spaced around an axis of the first cyclone. This provides a compact arrangement which is balanced for ease of manipulation. It is more preferable that each of the second cyclones has an end which projects into the first cyclone so as to provide a convenient balance of dirt collecting capacity and overall volume of the cyclonic separator. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       An embodiment of the invention will now be described with reference to the accompanying drawings, in which: 
         FIG. 1  shows a handheld cleaning appliance according to the invention; 
         FIG. 2  is a side view of the appliance of  FIG. 1 ; and 
         FIG. 3  is a longitudinal cross section through the cyclonic separating apparatus forming part of the appliance of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIGS. 1 and 2  show a handheld vacuum cleaner  10 . The handheld 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 handheld vacuum cleaner  10  in use. A cyclonic separator  100  is attached to the main body  12 . A dirty air inlet  18  extends from a portion of the cyclonic separator  100  remote from the main body  12 . A brush tool  22  is slidably mounted on the distal end of the dirty air inlet  18 . A set of exhaust vents  24  are provided on the main body  12  for exhausting air from the handheld vacuum cleaner  10 . 
     The cyclonic separator  100  is located between the main body  12  and the dirty air inlet  18 . Consequently, the cyclonic separator  100  is located between the handle  16  and the dirty air inlet  18 . The cyclonic separator  100  has a longitudinal axis  26  which extends in a generally upright direction so that the axis  26 , and therefore the cyclonic separator  100 , lies substantially parallel to the direction in which the handle  16  extends. 
     The orientation of the handle  16  is such that, when the user grips the handle  16 , the user&#39;s hand forms a fist in a manner similar to that adopted when gripping a saw. This ensures that the user&#39;s wrist is not strained more than necessary when manipulating the handheld vacuum cleaner  10  for cleaning purposes. The cyclonic separator  100  is positioned close to the handle  16  which also reduces the moment applied to the user&#39;s wrist when the handheld vacuum cleaner  10  is in use. The handle  16  carries an on/off switch  20  in the form of a trigger for turning the vacuum cleaner motor on and off. 
     The cyclonic separating apparatus  100  forming part of the handheld vacuum cleaner  10  is shown in more detail in  FIG. 3 . The cyclonic separating apparatus  100  comprises a first cyclone  102  which has a longitudinal axis X-X and a wall  104 . An inlet  110  is formed in the upper portion of the wall  104 . The inlet  110  is in communication with the dirty air inlet  18  and forms a communication path between the dirty air inlet  18  and the interior of the first cyclone  102 . The air inlet  110  is arranged tangentially to the first cyclone  102  so that the incoming air is forced to follow a helical path around the interior of the first cyclone  102 . 
     A base  116  closes one end of the first cyclone  102 . The base  116  is pivotably mounted on the lower end of the first cyclone wall  104  by means of a hinge  118 . The base  116  is retained in a closed position (as shown the figures) by means of a catch  120 . 
     A shroud  121  is located inwardly of the wall  104  of the first 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 first cyclone  102 . The outlet  124  provides a communication path between the first cyclone  102  and a second cyclone assembly  126 . A lip  128  is provided at the base of the shroud  121 . The lip  128  has a plurality of through-holes  129  which are designed to allow air to pass through but to capture dirt and dust. 
     The second cyclone assembly  126  comprises a plurality of second cyclones  130  arranged in parallel with one another. In this embodiment, six second cyclones  130  are provided. The second cyclones  130  are arranged around the axis X-X of the first cyclone  102 . The arrangement of the second cyclones  130  is such that the second cyclones are spaced equi-angularly around the axis X-X. Each second 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 second cyclone  130 . A cone opening  136  is located at a second end of each second cyclone  130 . The plane of the cone opening  136  of each second cyclone  130  is inclined with respect to a longitudinal axis (not shown) of the respective further cyclone  130 . The cone opening  136  of each of the second cyclones  130  is in communication with a passageway  138  defined by a wall  140  located inwardly of the shroud  121 . 
     The second end of each second cyclone  130  projects into the interior of the first cyclone  102 . However, the first end of each second cyclone  130  lies outside the envelope of the first cyclone  102 . In the orientation shown, it is the lower end of each second cyclone  130  which projects into the upper end of the first cyclone  102 . The inlet  110  is also arranged at the upper end of the first cyclone  102  so that the inlet  110  is located in the region of the cyclonic separator  100  in which the first and second cyclones  102 ,  130  overlap. Because the first ends of the second cyclones  130  lie outside the envelope of the first cyclone, this region of the cyclone separator  100  lies intermediate the upper end of the cyclone separator  100  and the lower end of the cyclone separator  100 . Connecting the dirty air inlet  18  to the cyclone separator  100  at an intermediate portion thereof is beneficial for the manipulation of the handheld vacuum cleaner  10  and avoids the lower extremities of the appliance being accidentally knocked on surfaces away from the area being cleaned. 
     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 delimited by the base  116  and the sides of the first and second portions  144 ,  146  of the collector  142 . 
     Each of the air outlets  134  of the second 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 handheld 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 and can also include a fine filter material. The pre-motor filter  152  is designed to prevent any fine dust particles from entering the motor and causing damage thereto. 
     In use, when the on/off switch  20  is depressed, the motor and fan unit draws a flow of dirt-laden air into the dirty air inlet  18  and then into the cyclonic separator  100 . Dirt-laden air enters the cyclonic separator  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 first cyclone  102 . 
     The partially-cleaned airflow then flows back up the interior of the first cyclone  102  and exits the first 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 second cyclones  130 . Each of the second cyclones  130  has a diameter which is smaller than that of the first cyclone  102 . Therefore, the second cyclones  130  are able to separate smaller particles of dirt and dust from the partially-cleaned airflow than the first cyclone  102 . Separated dirt and dust exits the second 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 bottom of the collector  142  on the base  116 . 
     Cleaned air then flows back up the second cyclones  130 , exits the second 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 . 
     The first cyclone  102  and the 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 separator  100 . This allows efficient and reliable emptying of the dirt and dust from the cyclonic separator  100  at periodic intervals convenient to the user. 
     The invention is not limited to the precise details of the embodiment described above. For example, the number of second cyclones can be varied, as can the detail of their design, such as their cone angle, axis inclination and cone opening inclination. The collected dirt and dust can be released in other ways, such as by complete removal of the lower portion of the first cyclone  102 , and the location of the on/off switch may be varied.

Technology Classification (CPC): 8