Patent Publication Number: US-9427124-B2

Title: Vacuum cleaner

Description:
REFERENCE TO RELATED APPLICATIONS 
     This application claims the priority of United Kingdom Application No. 1210604.3, filed Jun. 14, 2012, the entire contents of which are incorporated herein by reference. 
     FIELD OF THE INVENTION 
     The present invention relates to the field of cyclonic vacuum cleaners, and in particular vacuum cleaners which comprise a removable dust separator. The dust separator itself may be cyclonic or it may be bagged. The vacuum cleaner may be an upright vacuum cleaner or it may be some other type of cleaner (cylinder, handheld, stick vac cleaner etc.). 
     BACKGROUND OF THE INVENTION 
     Cyclonic vacuum cleaners work using cyclonic action to separate out dust and dirt from the dirty air sucked into the cleaner. They generally comprise at least one cyclonic chamber in which the air spins at high speed under the prevailing vacuum pressure, and a respective dirt collection chamber which is arranged to collect the dirt flung out from this fast-spinning airflow. The cyclone chamber and dirt collection chamber are together referred to as a cyclonic stage of separation. 
     The separation efficiency of a cyclonic stage varies with particle size. Consequently, in order to deal with the range in particles sizes typically found in household dust, a tuned series of cyclonic stages is typically provided. In this sort of multi-stage arrangement, the first stage tends to remove the relatively large particles and then each successive stage is optimized to remove successively smaller particles. The various stages may be packaged together as a single, cyclonic separator, which may be removable from the vacuum cleaner to allow easy emptying of the dirt collection chambers.  FIG. 1  shows a typical example of this sort of general arrangement. Here, the vacuum cleaner  1  is an upright vacuum cleaner and a removable multi-stage cyclonic separator  3  is mounted in an upright position on a rolling support assembly  5  forming part of the cleaner  1 . 
       FIG. 2  is a section through the cyclonic separator  3 . Here the first cyclonic stage—or ‘primary’—comprises a relatively large, cylindrical bin  7  which acts both as a cyclone chamber and as a dirt-collection chamber. The second cyclonic stage comprises a plurality of smaller, tapered cyclone chambers  9  arranged in parallel (to reduce pressure losses across the secondary stage) which each feed into a second dirt collection chamber  11 —the so-called Fine Dust Collector (FDC). 
     The dirty air enters the cyclonic separator  3  through a tangential inlet  13  on the bin  7  (shown in  FIG. 1 ), which helps impart the necessary spin to the airflow inside the bin  7 . The air exits then exits the primary through a cylindrical mesh outlet—or ‘shroud’— 15  and from here is ducted to the secondary cyclone stage. The air exits the secondary cyclone chambers  9  through the top and is collected in a manifold  17 , from where it ducted down through the bottom of the cyclonic separator  3 —via a sock filter  19  (for separating very fine particles remaining in the airflow)—to the vac-motor. 
     SUMMARY OF THE INVENTION 
     According to the present invention there is provided a vacuum cleaner comprising a removable dust separator, the dust separator comprising an inlet duct and an outlet duct, the inlet duct being arranged for fluid connection to a dirty-air duct on the cleaner, and the outlet duct being arranged for fluid connection to a motor intake duct on the cleaner, the inlet duct and outlet duct sharing a common wall which divides the open ends of the ducts, an inlet duct sealing member being provided for forming an air-seal between the inlet duct and the dirty-air duct, and an outlet duct sealing member being provided for forming an air seal between the outlet duct and the motor intake duct. 
     In the arrangement of the present invention, the inlet duct and outlet duct are arranged so that they share a common wall. This is an efficient way of packaging the inlet duct and outlet duct in the cyclonic separator. 
     A potential drawback which has been identified with the use of a common wall separating the open ends of the ducts is that air can leak across the common wall between the two ducts, effectively short-circuiting the dirty-air duct to the motor intake duct. Consequently, dirty-air may be drawn in through the motor intake duct, risking damage to the motor. 
     The arrangement of the present invention addresses the problem of dirt ingress into the motor by providing two independent seals: an inlet duct sealing member for forming an air-seal between the inlet duct and the dirty-air duct, and an outlet duct sealing member which forms an air-seal between the outlet duct and the motor intake duct. In other words, there is a common wall section between the ducts, but not a common air-seal. Consequently, failure of either one of the sealing members does not necessarily create a short circuit between the ducts, despite the common wall section between the ducts. As a result, the risk of damage to the motor caused by dust ingress is significantly reduced. 
     The motor intake duct may be arranged in accordance with another aspect of the present invention so that it connects directly to atmosphere across the air-seal formed by the outlet duct sealing member. Consequently, this creates a leakage path from atmosphere directly into the motor intake duct in the event of failure of the air-seal. The leakage path bypasses the cyclonic separator altogether: in effect, the motor intake short-circuits to atmosphere if the duct sealing member fails. There is no closed path between the motor intake duct and the dirty air duct, across the air-seal formed by the outlet duct sealing member. Ingress of fine dust from the dirty-air duct into the motor intake is significantly reduced, even if both sealing members fail. 
     The open end of the outlet duct may be arranged to fit over the end of the motor intake duct in order to form a bypass leakage channel between the walls of the ducts, which channel connects the motor intake duct to atmosphere. This is a convenient arrangement for connecting the motor intake duct to atmosphere and the outlet duct also advantageously cowls the entrance to the motor intake duct. In this arrangement, the motor intake duct can also be extended a considerable distance up inside the outlet duct, if desired. 
     The duct sealing member may be arranged so that it sits inside the leakage channel formed between the ducts. In a particular arrangement, the duct sealing member is fixedly mounted on the outside of the motor intake duct and is arranged to form a seal against the inside of the outlet duct. The duct sealing member may be a lip seal. The open end of the inlet duct may fit over the end of the dirty-air duct. The inlet duct sealing member may be fixedly mounted on the outside of the dirty-air duct and be arranged to form a seal against the inside of the inlet duct. The inlet duct sealing member may be in the form of a lip seal. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the invention will now be described, with reference to the accompanying drawings, in which: 
         FIG. 1  is a perspective view of a conventional vacuum cleaner; 
         FIG. 2  is a sectional view through a conventional cyclonic separator; 
         FIG. 3  is a sectional view of the bottom part of a cyclonic separator according to the present invention; 
         FIG. 4  is a magnified sectional view of the area circled in  FIG. 3 ; and 
         FIG. 5  is a sectional view taken along C-C in  FIG. 3 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIGS. 3 to 5  illustrate the bottom part of a cyclonic separator  30  on a vacuum cleaner in accordance with the invention. Comparing the separator  30  to the conventional separator  3  shown in  FIG. 1 , the separator likewise comprises an annular, outer cylindrical bin  70  which constitutes the primary cyclone stage, an annular inner dirt collection chamber  110 —referred to below as the FDC—which is fed by a respective plurality of second-stage cyclone chambers (not shown) and an outlet duct  190  which takes the air from an exit manifold (not shown) at the top of the cyclone separator  30  and ducts this air down through the base  230  of the cyclonic separator  30 , to the motor, as indicated by the arrow. 
     The cyclonic separator  30  differs from the separator shown in  FIG. 2  in that the dirty air is also delivered to the primary up through the base of the cyclone separator—again, indicated by an arrow in  FIG. 3 —so that there is actually also an inlet duct  290  running immediately alongside the outlet duct  190 . 
     The outlet duct  190  shares a section of the circular inner wall  310  with the FDC  110 . This common wall section  310   a  divides the open end  190   a  of the outlet duct  190  from the annular open end  110   a  of the FDC  110 . The inlet duct  290  likewise shares a section of the circular inner wall  310  with the FDC  110 . This common wall section  310   b  divides the open end  290   a  of the inlet duct  290  from the annular open end  110   a  of the FDC  110 . 
     In addition, the inlet duct  290  and the outlet duct  190  together share a common wall section  330 , which divides the open ends  190   a,    290   a  of the ducts  190 ,  290 . This common wall section  330  runs diametrically, so that the two ducts  190 ,  290  each have a corresponding semi-circular cross section (the corners of the semi-circle are in each case blended to reduce pressure losses), but this is not essential: the common wall section  330  could be arranged along some other chord line of the circular wall  310 , for example. 
     The base  230  takes the form of an annular, hinged cover which is provided to close off the annular open end  110   a  of the FDC  110 . The annular area of the cover  230  is such that, in this example, the cover  230  also closes off the annular open end of the outer bin  70 . This provides for simultaneous emptying of the FDC  110  and the outer bin  70 , but is not essential: a separate cover may be provided for the bin  70 . 
     The circular inner wall  310  of the FDC  110  extends through the central hole in the annular cover  230  when the cover  230  is in the closed position, shown in  FIG. 3 . 
     An annular, cover seal member  350  is provided on the upper surface of the cover  230 . This cover seal member  350  comprises a flexible sealing lip  350   a  which is arranged to form an air-seal between the cover and the outside surface of the circular wall  310  when the cover  230  is in the closed position. The cover seal member  350  additionally incorporates an annular gasket part  350   b  which seals against the lower end of the outer wall  370  of the FDC  110   a  to form an air-seal between the cover  230  and this outer wall  370 . Consequently, the cover  230  seals off the open end of the FDC  110  in the closed position. 
     The inlet duct  290  slidably engages an up-duct  370  on the vacuum cleaner (a sliding engagement is used so as not to hinder removal of the cyclonic separator  30  from the vacuum cleaner as and when required: the ducts simply slide apart). This up-duct  370  is a dirty-air duct—upstream of the cyclonic separator  30 —which ducts dirty air drawn in through the cleaner head to the cyclonic separator  30 . An inlet duct sealing member  390  is provided, near the upper end of the dirty-air duct  370 , in the form of a flexible lip seal. This lip seal  390  seals against the inside of the inlet duct  290  on the cyclonic separator  30 , forming an air-seal between the inlet duct  290  and the dirty-air duct  370 . 
     The outlet duct  190  likewise slidably engages an up-duct  410  on the vacuum cleaner. This second up-duct  410  is a motor intake duct—downstream of the cyclonic separator  30 —which ducts clean air exiting the outlet duct  190  to the intake on the main vac-motor. An outlet duct sealing member  430  is provided, near the upper end of the motor intake duct  410 , in the form of a flexible lip seal. This lip seal  430  seals against the inside of the outlet duct  190  on the cyclonic separator  30 , forming an air-seal between the outlet duct  190  and the motor intake duct  410 . 
     The cover seal member  350  and the outlet duct sealing member  430  act independently from one another. Consequently, both seals are required to fail in order to short circuit the FDC  110  and the motor intake duct  410  (indicated by the dotted arrow in  FIG. 3 ). This is therefore a more reliable sealing arrangement than the conventional sealing arrangement described in  FIG. 2 . 
     Similarly, the inlet duct sealing member  390  and the outlet duct sealing member  430  act independently from one another. Consequently, both seals are required to fail in order to short circuit the dirty air duct  370  and the motor intake duct  410  (indicated by the dotted arrow in  FIG. 4 ). 
     In fact, the specific arrangement described is designed so that a short circuit between the FDC  110  and the motor intake duct  410  is unlikely even in the event of failure of both the cover sealing member  350  and the outlet duct sealing member  430 . This is because the motor intake duct  410  connects directly to atmosphere across the air-seal formed by the outlet duct sealing member  430 . Consequently, failure of the duct sealing member  430  creates a bypass leakage path (indicated by the solid arrow in  FIG. 4 ) which short-circuits the motor intake duct  410  to atmosphere, bypassing the FDC  110 . This significantly reduces dust ingress into the motor intake duct  410  if both sealing members  350 ,  430  fail, because in effect there is no closed path between the FDC  110  and the motor intake duct  410  across the air-seal formed by the outlet duct sealing member  430 . 
     Similarly, short circuit between the dirty-air duct  370  and the motor intake  410  is unlikely to occur because there is likewise no closed path between the dirty-air duct  370  and the motor intake duct  410 : the outlet duct sealing member  430  fails to atmosphere. 
     The motor intake duct  410  connects to atmosphere via an annular bypass channel  450  which is formed between the wall of the outlet duct  190  and the wall of the motor intake duct  410  extending inside the outlet duct  190 . The outlet duct sealing member  430  sits in the bypass channel  450  and, along with the duct walls, effectively forms an annular, open-ended plenum cavity at atmospheric pressure. 
     In the specific arrangement shown in  FIGS. 3 to 5 , the dirty-air duct  370  is also connected to atmosphere, via a respective annular bypass channel  470  in similar manner to the motor intake duct  410 , so that the dirty-air duct likewise short-circuits to atmosphere if the inlet duct sealing member fails. However, this is not necessary to prevent a closed path forming between the dirty-air duct  370  and the motor intake duct  410  if the motor intake duct  410  is itself connected to atmosphere across the air-seal formed by the outlet duct sealing member  430 . 
     The FDC is additionally connected to atmosphere, across the air-seal formed by the cover sealing member  350 , so that the FDC short circuits to atmosphere in the event of failure of the cover sealing member  350 . Again, this is not really necessary for preventing a closed path forming between the FDC  110  and the motor intake duct  410  if the motor intake duct  410  is itself connected to atmosphere across the air-seal formed by the outlet duct sealing member  430 .