Patent Document

REFERENCE TO RELATED APPLICATIONS 
     This application is a national stage application under 35 USC 371 of International Application No. PCT/GB2007/002532, filed Jul. 6, 2007, which claims the priority of United Kingdom Application Nos. 0614238.4 and 0618493.1, 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. 
     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. Examples of this type of vacuum cleaner are shown in GB1207278 and EP 1452118A. 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. 
     Whilst handheld vacuum cleaners incorporating cyclonic separators are efficient at separating dirt and dust from the incoming airflow, it is still prudent to provide a fine dust filter upstream of the motor to ensure that no dust can enter the motor and cause it to become damaged or unbalanced. It is therefore an object of the invention to provide a cyclonic handheld cleaning appliance in which the motor is protected without adversely affecting the ability of the cleaner to operate efficiently. 
     BACKGROUND OF THE INVENTION 
     The invention provides a handheld cleaning appliance comprising a dirty air inlet, a clean air outlet and a separator for separating dirt and dust from an airflow in an airflow path leading from the air inlet to the air outlet, the appliance further comprising a body housing a fan and motor for drawing air into the appliance via the dirty air inlet and the separator including at least one cyclone, characterised in that the separator and the body are releasably connected together about a chamber in the airflow path which is formed partly by the body and partly by the separator, the chamber housing a filter which is located upstream of the fan and motor and downstream of the or each cyclone. 
     By providing the handheld vacuum cleaner with a body and a separator which are releasably connected to one another about a chamber which houses a filter, the area of the filter can be made relatively large in comparison to the average cross-sectional area of the airflow path through the appliance. This is also achieved without adversely affecting the overall size of the appliance. 
     Preferably, the filter has an upstream surface having an area which is at least three times, more preferably at least five times, the cross-sectional area of the dirty air inlet. This ensures that the pressure drop across the filter is kept to a minimum. 
     In a preferred embodiment, the body and the separator are connected in a plane and the filter lies substantially in the said plane or adjacent the said plane and parallel thereto. This enables the filter to be easily accessed for regular maintenance which also enhances the performance of the appliance. 
    
    
     
       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 ; 
         FIG. 3  is a longitudinal cross section through the cyclonic separating apparatus forming part of the appliance of  FIG. 1 ; and 
         FIG. 4  is a perspective view showing separator of the appliance of  FIG. 1  released from the body thereof. 
     
    
    
     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  away 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 . The dirty air inlet  18  is mounted directly on the cyclonic separator  100  on the side remote from the main body  12 . 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 separator  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 part-cylindrical, part frustoconical 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 recess  152  which is much larger in cross-sectional area than the duct  150 . The purpose of the recess  152  will be described in further detail below. 
     In normal 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. 
       FIG. 4  shows the main body  12  of the handheld vacuum cleaner  10  separated from the cyclonic separator  100 . As can be seen in  FIG. 4 , the main body  12  comprises a recess  50  delimited by a lip  52 . This recess  50  corresponds to the recess  152  formed in the cyclonic separator  100 . The recess  152  is surrounded by a lip  154  which is dimensioned and designed to cooperate with the lip  52 . The dimensions of the lips  52 ,  154  are such that, when the body  12  and the separator  100  are brought into connecting engagement, the lips  52 ,  154  overlap in a sealing manner. The two recesses  50 ,  152  then combine to form a chamber in which a pre-motor filter  56  is housed. The filter  56  has a sealing rim  58  which abuts against one of the lips  52 ,  154  so that air cannot pass between the filter  56  and the lip  52 ,  154 . The cyclonic separator  100  and the main body  12  are held in this position by a catch  60 . 
     In its operative position, the filter  56  lies in or directly adjacent the plane in which the lips  52 ,  154  lie. The filter  56  also fills the entire area within the lips  52 ,  154  so as to maximise the area of the filter  56  which is presented to the airflow passing through the appliance  10 . The area of the upstream surface  56   a  of the filter  56  is designed to be as large as possible in comparison to the area of the dirty air inlet  18 . This reduces the pressure drop across the filter  56  and also increases the period between necessary maintenance washes of the filter  56 . The area of the upstream surface  56   a  of the filter  56  is more than five times the cross-sectional area of the dirty air inlet  18 . 
     When the cyclonic separator  100  is to be released from the body  12 , the catch  60  is depressed to allow the lips  52 ,  154  to be separated from one another. The removal of the separator  100  from the body  12  thus reveals the filter  56  allowing access for washing or replacement. 
     The invention is not limited to the precise details of the embodiment described above. For example, the separator need not be cyclonic. If it is, 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. The shape of the chamber and filter can be varied, as can the area in comparison to the area of the dirty air inlet.

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