Patent Publication Number: US-2005115411-A1

Title: Suction and filtering apparatus

Description:
FIELD OF THE INVENTION  
      The present invention concerns an air suction and filtering apparatus wherein the air sucked in is filtered of the dust and solid particles by means of a dry filter and a liquid bath filter. The two filters are arranged in series and a mixing chamber is made between them, in which the air, after being partly filtered in the dry filter, is mixed with a jet of clean water. The mixture of air and water thus obtained is conveyed into the liquid bath filter to make even the finer dust, which is more difficult to capture, precipitate therein.  
     BACKGROUND OF THE INVENTION  
      A suction and filtering apparatus is known, comprising a liquid bath filter containing water and, downstream, a dry filter.  
      A suction motor is arranged downstream of the dry filter. In this way the motor is able to generate a flow to suck in the air and dust between an inlet and an outlet of the filtering apparatus, so that the air passes first in the water contained in the liquid bath filter and then in the dry filter.  
      This known apparatus has the disadvantage, however, that the air and finer dust, which do not deposit in the liquid bath filter, are partly dampened by the water contained therein.  
      The dampened air and dust unfortunately dampen the dry filter too, and damage it, with the risk that the efficiency of its filtering power can be diminished.  
      Moreover, the dampened air and dust also cause the formation of damp deposits, which are difficult to remove, in the zone of passage between the liquid bath filter and the dry filter.  
      U.S. Pat. No. 4,676,811 discloses a cleaning apparatus comprising a first hermetic container containing a liquid, such as water. A second container, smaller than the first, is arranged inside the first container and is open on the bottom in order to allow the liquid to enter it too. The air to be cleaned enters the second container, where a second liquid is sprayed onto the air itself in order to dampen the solid particles, making them heavy and causing them to fall into the liquid on the bottom of the first container. The already dampened air exits from the second container and enters the first container through a Venturi-type scrubber, which is provided with a nozzle that sprays the already dampened air and in which the particles, before being sprayed, are further dampened in order to facilitate their fall into the water in the first container. The air introduced into the first container then flows above the liquid, passes through a pre-filter and, through a particulate air filter, comes out through a fan, as clean air.  
      In this known apparatus too the particles are separated from the air first by using a damp method, by means of sprays of liquid, and, subsequently, using a dry method, by means of the pre-filter and the filter. In this case too, the previously described disadvantages occur.  
      The Japanese patent application JP-A-08-112226 discloses a cleaning apparatus comprising, on the head side, a portion to suck in the dust, which is connected to a suction pump through an intermediate channel. A dry filter, consisting of a metal net and of a non-woven fabric, and a first portion to collect the dust captured by the dry filter are inserted into a first half of the intermediate channel, while a liquid bath filter, with water or a water solution, is inserted into the second half of the intermediate channel and constitutes a second portion to collect the dust.  
      In this cleaning apparatus the air sucked in is therefore filtered in the first half of the intermediate channel by means of a dry filter, and in the second half of the intermediate channel by means of a liquid bath filter. This known apparatus has the disadvantage, however, that, in the intermediate zone between the dry filter and the liquid bath filter, the air sucked in is in no way made heavier, or dampened, in order to encourage the dust to fall through gravity into the liquid bath.  
      Applicant has devised and embodied the present invention to overcome these shortcomings of the state of the art and to obtain further advantages.  
     SUMMARY OF THE INVENTION  
      The present invention is set forth and characterized essentially in the main claim, while the dependent claims describe other innovative characteristics of the invention.  
      One purpose of the invention is to achieve an air suction and filtering apparatus by means of which it is possible to completely separate the dust and the solid particles sucked in together with the air and, at the same time, to prevent the formation of unwanted deposits of said dust and solid particles.  
      Another purpose of the present invention is to achieve a suction and filtering apparatus wherein, at a first moment, the larger dust can be separated in a dry filter and, at a second moment, the finer dust can be separated in a liquid bath filter, and wherein the finer dust is encouraged to fall into the liquid bath filter.  
      In accordance with these purposes, an air suction and filtering apparatus according to the present invention comprises at least a first filtering unit and a second filtering unit, connected together in series, and air suction means able to create a flow of air between an inlet pipe, through the first filtering unit and, subsequently, through the second filtering unit, and an outlet aperture arranged downstream of the second filtering unit. To be more exact, the first filtering unit comprises a dry filter and the second filtering unit comprises a liquid bath filter. According to the invention, between the first filtering unit and the second filtering unit a mixing chamber is arranged, independent of the two filters, into which the air arriving from the dry filter is able to be conveyed. Moreover, water introduction means are provided, which are connected to the mixing chamber in order to introduce water therein, advantageously under pressure, in order to obtain an air-water mixture able to be conveyed to the liquid bath filter.  
      Advantageously, the water introduction means are able to create a vortical motion of the water in the mixing chamber, so as to facilitate the nebulization of the water and the absorption of the finer particles.  
      The apparatus according to the invention thus allows to separate the heaviest and/or largest particles in the dry filter, and subsequently, in the mixing chamber, to dampen the air with an injection of water, making the finer particles heavier, so as to encourage them to fall into the liquid bath filter.  
      With the apparatus according to the invention it is also possible to prevent the formation of deposits of damp dirt. In fact, the water to be introduced and mixed with the air sucked in arriving from the dry filter cleans the zones of passage of the air between the dry filter and the liquid bath filter.  
      The type of dry filter is not restricted in the field of the present invention. The dry filter can comprise for example a cyclone filter, a membrane filter or a net filter, a bag filter, filtering cloths or otherwise.  
      In one form of embodiment, the mixing chamber for the air and water is substantially cylindrical in shape, or shaped like a truncated cone, and is defined by an inner lateral wall, an outer lateral wall and a circular wall. The chamber is connected by means of respective inlet and outlet pipes, on the one side to the dry filter and on the other side to the liquid bath filter.  
      Advantageously both the water introduction means to introduce the water into the mixing chamber and also the inlet pipe to introduce the air arriving from the dry filter are arranged in proximity with the circular wall, so that both the water and the air are fed in a peripheral zone of the mixing chamber along the circular wall. On the contrary, the outlet pipe, which conveys the mixture of water outside the mixing chamber towards the liquid bath filter, is made in a central zone on one of the two lateral walls of the chamber itself. This configuration allows the formation of the aforementioned vortical motion of the mixture of air-water, from the peripheral zone towards the central zone of the mixing chamber.  
      According to a first embodiment, in order to induce the formation of said vortical motion, the water is introduced into the mixing chamber according to a trajectory that is tangential with respect to the circular wall of the mixing chamber.  
      According to a variant, inside the mixing chamber, in correspondence with the zone where the water, and respectively the air, is introduced, diversion elements are made, with a curved shape, such as platelets, fins or suchlike, which are able to induce a circular vortical motion of the mixture towards the central zone of the mixing chamber.  
      The water to be mixed can be taken both from a tank that is separate from the liquid bath filter and directly from the liquid bath filter itself. In this case the water contained in the liquid bath is suitably filtered before being injected again against the air sucked in.  
      Another purpose of the present invention is to obtain a suction and filtering apparatus of a multi-functional type, which can be used even only to dry filter the dust of a relatively large size, as in the case of crumbs or suchlike, or to suck in only liquids.  
      In accordance with this purpose, the suction and filtering apparatus according to the present invention comprises a by-pass pipe able to put the first filtering unit in direct connection with the suction means.  
      Closing means are provided to isolate the mixing chamber and to selectively open the by-pass pipe, in order to convey the flow of air directly to the suction means and then to the outlet aperture of the apparatus. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      These and other characteristics of the present invention will become apparent from the following description of a preferential form of embodiment, given as a non-restrictive example, with reference to the attached drawings wherein:  
       FIG. 1  is a three-dimensional view, partly in section, of a suction and filtering apparatus according to the present invention;  
       FIG. 2  is another three-dimensional view of the apparatus in  FIG. 1 ;  
       FIG. 3  is a view from above of the apparatus in  FIG. 1 ;  
       FIG. 4  shows a detail of the apparatus in  FIG. 1  in a first operating condition;  
       FIG. 5  shows the detail in  FIG. 4  in a second operating condition;  
       FIG. 6  is a part view of a variant of the apparatus in  FIG. 1 ;  
       FIG. 7  shows a variant of a detail of the apparatus in  FIG. 1 . 
    
    
     DETAILED DESCRIPTION OF A PREFERENTIAL FORM OF EMBODIMENT OF THE INVENTION  
      With reference to the  FIGS. 1 and 2 , a suction and filtering apparatus  10  according to the present invention comprises an inlet pipe  11  for the introduction of the air sucked in, an outlet aperture  15  for the filtered air and a suction motor  21  arranged between the inlet pipe  11  and the outlet aperture  15  in order to create a corresponding flow of air.  
      The apparatus  10  also comprises a tank  12 , closed at the top by means of a cover  13 , inside which a first filtering unit is made, comprising a dry filter  14 , and a second filtering unit, comprising a liquid bath filter, or water filter  16 . The latter is connected to the suction motor  21  by means of an intermediate pipe  17 . Between the suction motor  21  and the outlet aperture  15  there is also a unit to expel the air  19 , provided with another filter device of a known type, for example a HEPA filter.  
      According to a characteristic of the present invention, the apparatus  10  also comprises a mixing chamber  18 , independent of the water filter  16  and the dry filter  14 , into which water is able to be injected, to be mixed with the air arriving from the dry filter. The mixing chamber  18  is connected, in this case, to the dry filter  14 , by means of an inlet pipe  20  and is in communication with the water filter  16  by means of an outlet pipe  22 .  
      In this embodiment of the invention, the water to be injected into the mixing chamber  18  is taken directly from the water filter  16 , through a water introduction pipe  23 , by means of a feed pump  24 .  
      The dry filter  14  comprises a first container  26 , which can be removed from the tank  12 , connected at the rear with the inlet pipe  11  and closed at the top by a separating wall  28 .  
      Inside the first container  26  there is a filtering body  30 , tubular in shape, holed inside and attached at the top to the separating wall  28 . A vertical wall  30   a  is attached to one side of the filtering body  30  and is arranged, in this case, opposite the entrance to the inlet pipe  11 .  
      In this way, as it enters the first container  26 , the air hits the vertical wall  30   a  and causes the heavier and coarser particles to precipitate onto the bottom of the first container  26 .  
      The separating wall  28 , with the cover  13  of the tank  12 , defines an expansion chamber  31  for the air, which communicates on one side with the dry filter  14 , by means of a through hole  32 , and on the other side with the mixing chamber  18 , by means of the inlet pipe  20 . The through hole  32  is made in a central zone of the separating wall  28  in correspondence with the filtering body  30  below, so as to allow the air to pass into the expansion chamber  31 , after dry filtering.  
      According to a characteristic of the present invention, the expansion chamber  31  can be put into communication directly with the suction motor  21 , by means of a bypass  35  open towards the second filtering unit, so as to exclude the mixing chamber  18  from the suction path.  
      This solution is particularly useful in the event that it is sufficient to filter the air only with the dry filter, for example when crumbs or similar particles are sucked in.  
      To be more exact, above the separating wall  28  there is a shutter  33  able to slide linearly backwards and forwards between two operating positions.  
      In a forward operating position, not shown in the drawings, the shutter  33  closes the inlet pipe  20  and isolates the mixing chamber  18  from the flow of air in order to thus obtain a dry filtering of the air only. In correspondence with the forward operating position, the feed pump  24  is advantageously switched off.  
      In a retracted operating position, shown in  FIGS. 1 and 3 , the shutter  33  closes the by-pass  35  and keeps the expansion chamber  31  in communication with the mixing chamber  18 , by means of the inlet pipe  20 , in order to obtain a mixed type of filtering, that is to say, by means of which, after the air has been dry filtered of the coarser and heavier dust, it is mixed with water in the mixing chamber  18  in order to be subsequently filtered in the water filter  16 .  
      The mixing chamber  18  is made inside a cylindrical box-like body  36 , which is arranged at the front of the tank  12  and comprises an inner lateral wall  38 , an outer lateral wall, not shown in the drawings, and a cylindrical or circular wall  39 .  
      The outlet pipe  22  couples into a central zone of the inner lateral wall  38  and its upper end is connected with the water filter  16  by means of a joint  40 .  
      In the embodiment shown in  FIGS. 1-3 , the water introduction pipe  23  couples into an upper zone of the cylindrical wall  39 , in a substantially horizontal manner, so as to introduce the water into the mixing chamber  18  in a direction substantially tangential to the cylindrical wall  39 .  
      The jet of water thus introduced mixes with the air entering into the lower zone of the mixing chamber  18  from the inlet pipe  20 , forming a vortex which extends from the periphery towards the center of the mixing chamber  18  and is sucked in through the outlet pipe  22 , to fall in a cascade into the water filter  16 .  
      The formation of the vortex facilitates the nebulization of the water and allows a greater absorption of the fine dust in the water.  
      According to a variant shown in  FIG. 7 , the water introduction pipe  23  couples into the lower zone of the inner wall  38  of the mixing chamber  18 , while the inlet pipe  20  for the air arriving from the dry filter  14  couples into the cylindrical wall  39  in an upper zone of the mixing chamber  18 .  
      Inside the mixing chamber  18  there is a first diversion element  45 , curved, which is arranged in proximity with the zone where the air enters the mixing chamber  18  in order to induce a circular motion of the air towards the lower zone where there is a second diversion element  46 , which diverts the air upwards again.  
      The second diversion element  46  is joined in one piece with a third diversion element  47  which is arranged in proximity with the inlet zone of the water pumped inside the mixing chamber  18 . The water is sucked in due to the Venturi effect by the circulating air and is diverted upwards by the third diversion element  47 , according to a circular trajectory, mixing with the air itself.  
      The mixture of air and water is diverted, finally, by a fourth diversion element  48  towards the center of the mixing chamber  18  where there is a tubular element  49 , partly open, where the mixture forms a vortex which extends as far as into the outlet pipe  22 , and then falls, in this embodiment too, in a cascade into the water filter  16 .  
      The water filter  16  comprises a second container  50  ( FIGS. 4 and 5 ) for water, also removable from the tank  12  and connected at the upper part with the intermediate pipe  17  and at the lower part with the mixing chamber  18  by means of the water introduction pipe  23 .  
      To be more exact, upstream of the intermediate pipe  17  a seating  51  is attached for a safety float of a known type, not shown in the drawings, which is able to block the suction motor  21  in the event that the water level inside the second container  50  has reached a maximum level.  
      Under the second container  50 , moreover, in correspondence with the point where it connects with the feed pump  24 , there is a chamber  53  ( FIGS. 2, 4  and  5 ), communicating with the latter.  
      The connection between the chamber  53  and the bottom of the container  50  is obtained by means of a pair of spring valves  54  and  55 , which normally block the flow of water when the second container  50  is removed from the tank  12 .  
      The valve  54  comprises a tubular body  54   a  inside which a first rod  56  is able to slide, with a cross-shaped transverse section and able to be inserted in abutment in a mating tubular compartment  55   a  of the valve  55 , inside which a second rod  58  is able to slide, also with a cross-shaped transverse section.  
      Two helical springs  57  and  65  keep the rods  56  and  58  in a forward position, in which the valves  54  and  55  are in a closed position, with their sealing packings  63  and  66  thrust against the respective tubular bodies  54   a  and  55   a.    
      When the container  50  is inserted into the tank  12  ( FIG. 5 ), the abutment coupling of the tubular body  54   a  in the compartment  55   a  causes a compression in opposite directions of the respective springs  57  and  65  and the consequent opening of the passage of flow of water into the chamber  53  through the inter-spaces defined by the empty spaces of the cross-shaped rods  56  and  58 .  
      According to another characteristic of the present invention, the apparatus  10  as described heretofore can also be used only to suck in liquids.  
      For this use the filtering body  30  is removed from the respective container  26  and the latter is used simply as a collection container for the liquids sucked in like the container  50  of the liquid bath filter  16 .  
      The door  33  is positioned in its forward operating position and the feed pump  24  is de-activated.  
      When the suction motor  21  is driven, the liquids to be sucked in are momentarily collected in the first container  26  and subsequently in the second container  50 . When the level of liquids collected in the second container  50  reaches the maximum level, the safety float blocks the suction motor  21  and therefore the whole apparatus  10 .  
      It is clear, however, that modifications and/or additions of parts may be made to the suction and filtering apparatus  10  as described heretofore without departing from the field and scope of the present invention.  
      According to a variant, the dry filter  14  comprises a propeller element  130  ( FIG. 6 ), which is contained in a first container  126  connected at the lower part with the inlet pipe  11 .  
      The first container  126  is substantially cylindrical in shape and comprises an outer wall  131  and an inner wall  132 , coaxial to the outer wall  131  and in which through holes  133  are made. The inner wall  132  is attached, at a set distance, from the outer wall  131  and defines therewith an intermediate compartment  134 .  
      The propeller element  130  is able to induce a cyclonic motion in the air and in the solid particles sucked in with it, in order to obtain a first dry filtering of the air.  
      The heavier particles, in fact, having a greater speed, are thrust due to centrifugal force through the holes  133  against the outer wall  131  and are deposited, falling into the intermediate compartment  134 , on the bottom of the container  126 .  
      The lighter particles, instead, are drawn with the air into the expansion chamber  31 , made above the dry filter  14 .  
      It is also clear that, although the present invention has been described with reference to specific examples, the person of skill in the art shall certainly be able to embody many other equivalent forms of suction and filtering apparatus, all of which shall come within the field and scope of the present invention.