Patent Publication Number: US-6342084-B1

Title: Vacuum cleaner

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a vacuum cleaner. 
     2. Description of the Related Art 
     Vacuum cleaners typically include a vacuum motor and an air pervious bag for collecting material such as dust and other small particulate material. The vacuum motor induces an air flow through the bag and entrained material is collected in the bag. With known vacuum cleaners it is found that when the vacuum cleaner is new the degree of air flow generated through the bag by means of the vacuum motor is good and collection of material is achieved efficiently. 
     The efficiency of collection of material may be sustained if the vacuum cleaner is maintained regularly. However, it is often the case that vacuum cleaners are not maintained properly and this can then cause a build up of accumulated material in the bag. In this case the air flow is gradually reduced and thus the efficiency of collection of material is correspondingly reduced. 
     Furthermore, the reduced air flow leads to reduction of the cooling effect of the air on the vacuum motor. 
     In a backpack type vacuum cleaner, the orientation, in use, of the vacuum cleaner is such that a vacuum motor locates below a collection chamber, the collection chamber being provided with an air pervious collection bag. In operation, the motor creates a suction force which acts to draw air from an inlet located above the bag through the bag and the motor to an outlet located below the motor. With this configuration, as the bag fills with dust or particulate material, holes in the bag become blocked and the resistance to air flow caused by the bag is increased. As a result, over time, the more the vacuum cleaner is used, the lower the suction force of the vacuum cleaner and the lower the cooling effect of the air flow on the motor. 
     The present invention provides an apparatus which seeks, among other things, to alleviate the above mentioned problems. 
     BRIEF SUMMARY OF THE INVENTION 
     In accordance with one aspect of the present invention there is provided a vacuum cleaner apparatus which includes a vacuum motor, an air pervious membrane and an air pervious material collection bag, the vacuum motor being arranged to draw air downwardly in turn through the bag, the said membrane, and the motor so that, in use, the bag retains material entrained in the air, wherein there is also provided a spacing means located intermediate the said membrane and the bag for orienting the bag such that a first portion of the bag is adjacent the said membrane and a second portion of the bag is spaced from the said membrane. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     The present invention will now be described, by way of example, with reference to the accompanying drawings in which: 
     FIG. 1 is a schematic sectional view of a vacuum cleaner in accordance with the present invention; and 
     FIG. 2 is a diagrammatic perspective view of a spacing means of the vacuum cleaner shown in FIG.  1 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In the accompanying drawings, there is shown a vacuum cleaner  10  oriented for use, the vacuum cleaner  10  including a housing  12  containing a partition  14 . A vacuum motor  16  is mounted adjacent and upwardly of the partition  14 . The housing  12  includes a first casing  13  and a second casing  15 , the first casing  13  defining an inlet chamber  18  and the second casing  15  defining an intermediate chamber  17  and an outlet chamber  20 . Also provided is a lid  19  having an air inlet  21 , the lid  19  being fixed to the first casing  13  by releasable fixing means  23 . 
     The inlet chamber  18  contains an air pervious bag  22  arranged to collect dust and other small particulate material, the bag being formed of a material such as nylon or any other filter material which is sufficiently smooth to minimise cling of the dust or particulate material to the bag. The second casing  15  includes a perforated upper wall member  24  which includes an air pervious membrane in the form of a base portion  26 . 
     Further, mounted within the inlet chamber  18  in a central region thereof resting on the base portion  26  is a spacing means in the form of a substantially bell shaped member  28 . The bell shaped member  28  includes a perforated elongate substantially frusto-conical wall portion  30 , a perforated small end portion  32 , and a perforated large end portion  34  of substantially frusto-conical shape, the large end portion  34  being open. The configuration and location of the spacing means is such that the small end portion  32  locates adjacent the air inlet  21 . 
     The frusto-conical wall portion  30  is shaped such that outer and inner surfaces of the wall portion  30  subtend a shallow angle with a central longitudinal axis of the wall portion  30 . The frusto-conical large end portion  34  is shaped such that outer and inner surfaces of the large end portion  34  subtend an angle with the central longitudinal axis of the wall portion  30  which is greater than the angle subtended between the outer and inner surfaces of the wall portion and the central longitudinal axis. 
     The bell shaped member  28  also includes ribs  29  extending longitudinally of an outer surface of the bell shaped member  28 , and fixing means  31  for facilitating fixing of the bell shaped member to the base portion  26 . 
     The bag  22  is draped over an upper edge of the first casing  13  as shown in FIG.  1  and then would normally closely conform to the internal shape of the wall member  24  which includes the base portion  26 . However, because of the presence of the bell shaped member  28 , a central portion  34  of the bag  22  is draped over the bell shaped member  28  so that the central portion  34  is spaced further away from the motor  16  and the base portion  26  than would normally be the case. The central portion  34  is surrounded by an annular peripheral portion  35  which is disposed adjacent to the base portion  26 . 
     Thus, the bag  22  has a larger operative surface area through which air can pass than a normal bag in a conventional vacuum cleaner configuration. 
     Also, when there is an accumulation of material in the inlet chamber  18 , the central portion  34  is generally disposed above the accumulated material. Thus, even when the vacuum cleaner contains a substantial amount of accumulated material, substantially unimpeded air flow is achieved through the central portion  34  and effective cooling of the motor  16  can be maintained. 
     The outlet chamber  20  contains an exhaust  36 . 
     In the above described embodiment, the spacer member is in the form of a substantially bell shaped member  28 . However, it will be appreciated that the spacer member may have any shape which enables it to perform adequately in accordance with the present invention. For example, it may be frusto-conical in shape, parabolical in shape or hemispherical in shape. 
     The present invention may be applied to any vacuum cleaner but it is particularly envisaged for use with backpack type vacuum cleaners. 
     In use, the vacuum cleaner  10  is oriented as shown in FIG.  1 . The vacuum motor  16  is energised and thus induces an air flow downwardly in turn through the bag  22 , the spacer means, the base portion  26  and the motor  16 . Material entrained in the air flow is collected in the bag  22  around the central portion  34  thereof in the annular portion  35 . Since the central portion  34  locates, in use, generally above the collection material and adjacent the air inlet, even when the bag  22  is full a substantial air flow is still allowed to pass through the central portion  34  such that a relatively high suction force is maintained and cooling of the motor  16  is maintained. 
     It will be understood that the air flow passing through the vacuum cleaner follows a substantially cyclonic path with the majority of the dust and particulate material being entrained in a peripheral portion of the air flow. As a consequence, by virtue of the configuration and location of the spacer means relative to the air inlet, the dust or particulate material is urged towards the annular portion  35  of the bag and the central portion  34  of the bag is maintained relatively free from dust. It will also be understood that since the bag is formed of relatively smooth material, a majority of dust or particulate material which falls on the bag on and adjacent the central portion falls to the annular portion  35  by virtue of the suction force generated by the vacuum motor and under gravity. 
     Modifications and variations such as would be apparent to a skilled addressee are deemed to be within the scope of the present invention.