Patent Publication Number: US-2005132679-A1

Title: Dust collection system and related airlock

Description:
BACKGROUND OF THE INVENTION  
      1. Technical Field  
      The present invention relates generally to a dust collection system. More particularly, the invention relates to a dust collection system which separates lighter materials that are captured by a filter and heavy materials that fall into a collection bin. Specifically, the invention relates to a dust collection system including an airlock which allows the system to be used without a collection bin being sealed to the system.  
      2. Background Information  
      It is customary in the field of woodworking and other arts to provide a dust collection system connected to a series of machines wherein dust and various size particles of wood or other materials are removed from the machines. Such systems commonly have a separator which allows heavy material to fall into a collection bin while light material is captured by a filter. These dust collection systems are essentially a vacuum system allowing for the separation of the light and heavy materials.  
      One problem area that arises with the dust collection system relates to the need to empty the dust collection bin. Aside from the intake and exhaust openings, the dust collection systems are generally sealed throughout to ensure that dust and heavier particulate matter is not discharged in undesired places. Thus, the dust collection bin is sealed to the remainder of the system. Additionally, the dust collection bin has traditionally been sealed to the system in order to assure that a negative pressure is consistently realized within the system. Several problems arise related to the need to provide a seal between a collection bin and the rest of the system. One of the problems is that in order to empty the dust collection bin without discharging both light and heavy materials out of the system in an uncontrolled fashion, the system must be turned off. Another problem is that the connections making the seal with the collection bin are typically cumbersome, thus making removal of the bin difficult and time consuming. A further problem relates to the size of collection bins. Commonly, a collection bin may be a 55-gallon or similar size drum, which makes the bin unwieldy and difficult to empty especially when full. Resolution of these problems is a primary concern herein.  
      Thus, the art desires a dust collection system wherein the system need not be turned off in order to empty a dust collection bin. Further, it is desirable to create a system having a dust collection bin separated from the system to eliminate the need for a cumbersome seal. Further, it is desirable that small, and thus relatively light-weight, collection bins can be used to facilitate their movement for emptying. A dust collection system that eliminates the need for a collection bin altogether is likewise desirable. For instance, the dust collection system could drop the heavy material onto a pallet or a conveyor system if desired.  
     BRIEF SUMMARY OF THE INVENTION  
      The present invention provides an airlock having a housing defining an interior chamber, an entrance hole and an exit hole, each hole being in fluid communication with the interior chamber; a rotor body disposed within the interior chamber and being rotatable about a longitudinal axis; and the rotor body defining at least one airlock chamber so that at no time is there fluid communication between the entrance hole and the exit hole.  
      The present invention further provides a dust collection system having a blower in fluid communication with a source of particulate material and with a separator; the particulate material comprising light material and heavy material separatable by the separator; the separator in fluid communication with a filter for capturing the lighter material; and an airlock for receiving and discharging the heavy material; the airlock comprising a housing defining an interior chamber, an entrance hole and an exit hole, each hole being in fluid communication with the interior chamber; a rotor body disposed within the interior chamber and being rotatable about a longitudinal axis; and the rotor body defining at least one airlock chamber so that at no time is there fluid communication between the entrance hole and the exit hole.  
      The present invention also provides a method of collecting particulate material comprising the steps of providing a particulate material collection system having a blower in communication with sources of particulate material comprising light material and heavy material; the blower being in communication with a separator; the separator being in communication with a filter for capturing the light material; an airlock being in fluid communication with the separator; the airlock comprising a housing defining an interior chamber, an entrance hole and an exit hole, each hole being in fluid communication with the interior chamber; a rotor body disposed within the interior chamber and being rotatable about a longitudinal axis; and the rotor body defining at least one airlock chamber so that at no time is there fluid communication between the entrance hole and the exit hole; operating the blower to move the particulate material through the system; collecting a portion of the heavy material in the at least one airlock chamber; and rotating the rotor body to discharge the portion of the heavy material from the at least one airlock chamber. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS  
       FIG. 1  is a schematic view of a first embodiment of the airlock of the present invention connected to a typical dust collection system.  
       FIG. 2  is a perspective view of the first embodiment of the present invention.  
       FIG. 3  is an exploded perspective view of the first embodiment of the invention.  
       FIG. 4  is a sectional view of the first embodiment of the invention as seen from the side.  
       FIG. 5  is a sectional view taken along line  5 - 5  of  FIG. 4 .  
       FIG. 6  is a fragmentary sectional view of the dust collection system shown in  FIG. 1  showing an initial accumulation of heavy material falling into an airlock chamber between a pair of adjacent blades, with a rotated position of the blades being shown in phantom.  
       FIG. 7  is similar to  FIG. 6  but shows the blades of the airlock rotated 90degrees from the position shown in  FIG. 6 , with the initial accumulation having moved downwardly and laterally to an intermediate position, and subsequent heavy material in another airlock chamber between a second pair of adjacent blades.  
       FIG. 8  is similar to  FIG. 7  except that the blades of the airlock are rotated an additional 90 degrees to show the initial accumulation being discharged downwardly out of the airlock and subsequent heavy material in another airlock chamber between a third pair of adjacent blades.  
       FIG. 9  is an exploded perspective view of a second embodiment of the present invention.  
       FIG. 10  is a sectional view of the second embodiment of the present invention as seen from the side.  
       FIG. 11  is a partially exploded perspective view of a third embodiment of the present invention.  
       FIG. 12  is a perspective view of the third embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      An airlock of the present invention, used with a dust collection system, is indicated generally at  10  and is shown particularly in  FIGS. 1-8 . Airlock  10  is used as a component of dust collection system  12 , as seen in  FIG. 1 , which removes dust and other particulate material from machines  14 . Dust collection system  12  includes pipes  16  in fluid communication with machines  14  and blower  18 . Another pipe  20  is in fluid communication with blower  18  and separator  22 . Separator  22  in turn is in fluid communication with filter  24  extending upwardly therefrom and with airlock  10  there below. Dust collection system  12  further includes a heavy material  26  collection site, which may be a collection bin  28 .  
      Referring to  FIG. 2 , airlock  10  includes an electric motor  30  as its power source and a gear box  32  which is connected to motor  30 . In turn, gear box  32  is connected to mounting member  34 , which is mounted on mounting plate  36 . Mounting plate  36  is connected to one of a pair of caps  38 , each defining a central hole  40  and a plurality of mounting holes  42  adjacent an outer perimeter  44  of cap  38 .  
      Airlock  10  further includes a blade housing which comprises the pair of opposed end walls or caps  38  and a hollow cylinder  46  having a sidewall  45 , a first end  48  and a second end  50 . Caps  38  are connected to cylinder  46  at first end  48  and second end  50  respectively by threaded rods  52  and nuts  54 . The blade housing defines an interior chamber  56 . The blade housing has an inner surface which comprises an inner surface  47  of cylinder  46  and inner surface  39  of each cap  38 . Cylinder  46  defines an entrance hole  58  and an exit hole  60  in opposed relation to entrance hole  58 . Referring to  FIGS. 24 , Entrance hole  58  includes a leading edged  55  and a trailing edge  57 , and exit hole  60  includes a leading edge  59  and a trailing edge  61 . A cylindrical entry duct  62  extends upwardly from cylinder  46  and defines an entrance opening  64  in fluid communication with entrance hole  58 . Entry duct  62  further includes a stop in the form of an inwardly extending annular flange  66 . The lower end of separator  22  is inserted into entry duct  62  of airlock  10  to form an air tight seal between the lower portion of separator  22  and entry duct  62 . The insertion of lower portion of separator  22  into entry duct  62  of airlock  10  is limited by annular flange  66 . An exit duct  68  extends downwardly from cylinder  46  and defines an exit opening  70  in fluid communication with exit hole  60 .  
      Airlock  10  further includes a rotor body, which is preferably a blade assembly  72  comprising a blade shaft  74 , a plurality of rectangular blades  76  and a pair of opposed circular end plates  78 . Blade assembly  72  defines an airlock chamber  77  between each adjacent pair of blades  76  and between wedge-shaped portions of respective end plates  78 . Blade shaft  74  has a longitudinal axis  80  and is connected to a drive shaft  82  extending outwardly from gear box  32 . Drive shaft  82  is coaxial with longitudinal axis  80  of the blade shaft  74 . Blades  76  extend radially outwardly from blade shaft  74 , each blade  76  having an outer perimeter  84  comprising an outer edge  86  and a pair of opposed parallel ends  88 , each of which are perpendicular to outer edge  86 .  
      Blade assembly  72  is disposed within interior chamber  56  with blade shaft  74  extending through each of central holes  40  of respective caps  38 . Outer surfaces  83  of respective end plates  78  lie adjacent the respective inner surfaces  39  of caps  38 , thereby limiting the lateral movement of blade assembly  72  along longitudinal axis  80 . Each outer perimeter  79  of end plates  78  is continuously adjacent inner surface  47  of cylinder  46 . The outer edge  86  of each blade  76  is also continuously adjacent inner surface  47  when outer edge  86  of blade  76  is not in communication with either entrance hole  58  or exit hole  60  of cylinder  46 . Said another way, outer edge  86  of a given blade  76  is continuously adjacent inner surface  47  when the given blade  76  is disposed between leading edge  55  of entrance hole  58  and trailing edge  61  of exit hole  60  or when the given blade  76  is disposed between trailing edge  57  of entrance hole  58  and leading edge  59  of exit hole  60 . (It is noted, however, that certain alternately-shaped blades may curve so that the outer edge of the blade may be continuously adjacent inner surface  47  while certain portions of those blades are not disposed between leading edge  55  of entrance hole  58  and trailing edge  61  of exit hole  60  or between trailing edge  57  of entrance hole  58  and leading edge  59  of exit hole  60 .) End plates  78  are connected to either blade  76  or blade shaft  74  or both such that inner surface  81  of each end plate  78  lies continuously adjacent a respective end  88  of blade  76  and also continuously adjacent blade shaft  74 .  
      In the case of cylinder  46  and each blade  76 , outer edge  86  of blade  76  is always continuously adjacent inner surface  47  of cylinder  46  when edge  86  is not in communication with either hole  58  or  60 . This is due to the fact that any cross-section of cylinder  46  normal to longitudinal axis  80  defines a circle or a pair of concentric arcs. Thus, all points along inner surface  47  are equidistant from axis  80  and corresponding points on outer edge  86  of blade  76  rotate along a circular path closely adjacent to inner surface  47 . However, an airlock similar to airlock  10  may function properly even where the cross-section as discussed above in not circular. Thus, it is not required that outer edge  86  of blade  76  or a perimeter of a blade always be continuously adjacent the inner surface of the blade housing. Rather, where, as in the preferred embodiment, outer edge  86  is coplanar with longitudinal axis  80 , airlock  10  will operate properly as long as at all times, the outer edge  86  of at least one blade  76  is continuously adjacent inner surface  47  when disposed between leading edge  55  of entrance hole  58  and trailing edge  61  of exit hole  60  and simultaneously the outer edge  86  of at least one other blade  76  is continuously adjacent inner surface  47  when disposed between trailing edge  57  of entrance hole  58  and leading edge  59  of exit hole  60 . Most importantly and more broadly stated, blade assembly  72  defines at least one airlock chamber  77  so that at no time is there fluid communication between entrance hole  58  and exit hole  60 , as explained in more detail further below.  
      In operation, dust collection system  12  works generally as follows. Machines  14  create various sizes of particulate material, such as dust, small wood chips, metal shavings and so forth. In reference to system  12 , these materials can be broadly broken into light materials and heavy materials  26 . Blower  18  creates a pressure differential between machines  14  and blower  18  amounting to a suction from machines  14  towards blower  18  so that the heavy and light materials are entrained in air and moved through pipe  16  into blower  18  and then are blown out of blower  18  through pipe  20 . The materials exit pipe  20  into separator  22 , which has a larger diameter than pipe  20 , thus reducing the velocity of the air moving through the system. The light particles remain entrained in the upward airflow that moves through filter  24  while the heavy material  26  falls downwardly from separator  22  into airlock  10 . Ultimately, heavy material  26  is discharged from airlock  10  into collection bin  28  or onto another collection site. The light material is captured by filter  24 .  
      In accordance with the present invention, airlock  10  functions as follows. Motor  30  is activated to provide a source of power to rotate drive shaft  82  via gear box  32 , which is used to control the rotational velocity of drive shaft  82  and in turn blade shaft  74  and blades  76 . Generally, the rotational velocity of blade shaft  74  and blades  76  is relatively slow and is intended to allow heavy material  76  to be discharged from airlock  10  by gravitational force alone. Thus, the rotational velocity is generally not intended to significantly effect the velocity with which heavy material  26  is discharged from airlock  10 , although it may impart such an effect. Typically, blades  76  rotate at a constant velocity regardless of how full airlock  10  is. Outer perimeters  79  of respective end plates  78  and outer edges  86  of respective blade  76  lie closely adjacent or are in contact with inner surface  47  of cylinder  46 , and may create an airtight seal between these respective surfaces where desired or needed. This is also true of the close proximity between each end plate  78  and each of blade  76  and blade shaft  74 .  
       FIGS. 6-8  further show the function of airlock  10 .  FIG. 6  shows the flow of air through the system and the movement of the light material and heavy material  26  as the air and particulate materials exit pipe  20  and enter separator  22 , which separates the light and heavy materials in a manner commonly known in the art. The solid black arrows shown within pipe  20  and separator  22  and pointing upward towards filter  24  indicate air flow and may further represent the light material for the purposes herein. The broad arrows pointing downwardly indicate the direction of flow of heavy material  26  into airlock  10 . The light material follows the upward airflow and is captured by filter  24 . Heavy material  26  falls downwardly into airlock  10  so that it lies in an airlock chamber  77 . The arrows in airlock  10  of  FIG. 6  indicate the direction of rotation of blade shaft  74  and blade  76  about longitudinal axis  80 . In  FIG. 6 , an initial accumulation of heavy material  26  is seen in an upward orientation. As shown in  FIG. 7 , initial accumulation of heavy material  26  has moved to a lateral position while a second subsequent accumulation of heavy material  26  is in another airlock chamber  77  in the upper position as blades  76  have rotated approximately 90 degrees counterclockwise from their position in  FIG. 6 .  FIG. 8  shows blades  76  further rotated another 90 degrees so that the initial accumulation of heavy material  26  is discharged by gravity downwardly through exit duct  68  while the second accumulation is in the lateral position and a third subsequent accumulation is in yet another airlock chamber  77  in the upper position.  
      In accordance with the present invention, the rotor body or blade assembly  72  defining airlock chambers  77  is configured to prevent fluid communication between entrance hole  58  and exit hole  60  at all times, as further described below. Airlock  10  does not require a seal between the rotor body or blade assembly  72  and inner surface  47  of housing or cylinder  46 , although a seal is preferable where it is desirable or necessary to prevent any bleed through of air or small particulate material through airlock  10 . Generally, it is sufficient that blade assembly  72  and inner surface  47  are closely adjacent one another so as to create a minimal-leakage arrangement. Thus, when blade assembly  72  defining airlock chambers  77  is configured to prevent fluid communication between entrance hole  58  and exit hole  60  at all times, it means either that a seal is formed between blade assembly  72  and the inner surface of the blade housing or that the amount of leakage between blade assembly  72  and the inner surface of the housing is minimal and insignificant in terms of the purpose for which the airlock is to be used. Obviously, in certain environments, a certain increase in the degree of such leakage may be acceptable. However, it is clearly beneficial in general to minimize such leakage to the greatest degree possible within reasonable limits and cost factors.  
      Because airlock  10  either creates an airtight seal or allows minimal leakage at all times while blades  76  are rotating about axis  80 , there is no need to form a further seal between dust collection system  12  and a collection bin  28 . Thus, if collection bin  28  is used, there is no need to disconnect, re-connect or ensure a seal between collection bin  28  and system  12 . Further, there is no need to turn blower  18  off in order to remove and empty collection bin  28 . Another collection bin may be easily inserted with little or no spillage of heavy material  26  while bin  28  is being emptied. Alternatively, by way of example, heavy material  26  may be discharged into a collection bin having wheels or onto a pallet or conveyor for added convenience in removing accumulations material  26 .  
      A second embodiment of the airlock of the present invention is indicated generally at  100  and is shown in  FIGS. 9-10 . Airlock  100  is similar to airlock  10  except that a slightly different blade assembly  172  includes no end plates  78 . Otherwise, all the numbering in relation to airlock  100  is the same as in regard to airlock  10 . Due to the lack of end plates  78 , ends  88  of blades  76  lie adjacent respective inner surfaces  39  of caps  38 . Once again, the term adjacent means lying closely adjacent or in contact with, and thus in the second embodiment, an airtight seal or minimal-leakage arrangement is maintained as described above, while also including a seal or minimal-leakage arrangement between ends  88  and respective surfaces  39 . In the second embodiment, the airtight seal or minimal-leakage arrangement may be described as being between the inner surface of the blade housing and outer perimeter  84  of each blade  76 . Blade assembly  172  defines an airlock chamber  77  between each adjacent pair of blades  76  and between wedge-shaped portions of respective caps  38 .  
      In operation, airlock  100 , except in regard to the differences noted between airlock  10  and airlock  100 , functions in the same manner as airlock  10 .  
      A third embodiment of the airlock of the present invention is indicated generally at  200  and is shown in  FIGS. 11 -12 . Airlock  200  is similar to airlock  100  except that the blade housing and entry and exit ducts are formed differently and the ducts have a rectangular cross-section. Blade shaft  74  and blades  76  are the same as in airlock  100 . The blade housing and entry duct  262  and exit duct  268  are all formed by a pair of opposed end walls  238  and a pair of opposed sidewalls  240 . Each end wall  238  is generally rectangular and has a pair of opposed arcuate sections  242  extending outwardly from the long sides of the rectangle. Each end wall  238  defines a generally central hole  244  and a plurality of mounting holes  246  adjacent an outer perimeter  248  of end wall  238 . Each end wall  238  further includes an inner surface  250  and an outer surface  252  and defines a pair of grooves or slots  254  extending inwardly from inner surface  250  adjacent outer perimeter  248 . Sidewalls  240  have a pair of opposed ends  256  which fit into respective slots  254  of respective end walls  238  to form a tongue in groove fit. Sidewalls  240  further include a rectangular upper portion  258 , a rectangular lower portion  260  and a middle portion  264  disposed between and connected to upper portion  258  and lower portion  260 . Middle portion  264  is substantially an arc of a cylinder and has an inner surface  266 . In conjunction with portions of respective end walls  238 , the pair of opposed middle portions  264  define an interior chamber  270  therebetween. In combination with portions of respective end walls  238 , upper portions  258  of sidewalls  240  form entry duct  262  defining entrance opening  272 . In combination with portions of respective end walls  238 , lower portions  260  of sidewalls  240  form an exit duct  268  defining an exit opening  274 .  
      In operation, airlock  200  is substantially similar to airlock  100 . The distinction is only related to the specifics of where the air tight seals or minimal-leakage arrangements are formed, which are nonetheless analogous to those of airlock  100 . Specifically, outer edge  86  of blades  76  lie adjacent inner surface  266  of middle section  264  to form one area of the seal or minimal-leakage arrangement. The other portion of the seal or minimal-leakage arrangement is formed between each end  88  of blade  76  and inner surface  250  of respective end walls  238 . Otherwise, as with airlock  100 , motor  30  is connected to gear box  32  and mounted on mounting member  34 , which is in turn mounted on mounting plate  36 . In the case of airlock  200 , mounting plate  36  is mounted on one end wall  238 , but the function otherwise is the same. Airlock  200  allows for an easier connection with dust collection system ducts having a rectangular shape.  
      It will be understood that a variety of changes could be made to structures described herein without departing from the spirit of the invention. For example, blade assembly  72  is but one type of rotor body which may rotate about longitudinal axis  80  so that airlock of the present invention may operate properly. Most importantly, the rotor body defines at least one airlock chamber so that at no time is there fluid communication between the entrance hole and the exit hole. Thus, for instance, the rotor body may be a solid body with an airlock chamber formed therein, like a solid cylinder with a wedge cut out of it. Alternately, the rotor body may be hollow. Rotor bodies may have a wide variety of shapes, as noted more particularly below with regard to a rotor body comprising a blade assembly and blades.  
      An airlock may have only one airlock chamber, for example, a solid or hollow cylinder with one airlock chamber formed therein. In this case, the airlock chamber would receive heavy materials  26  from the rest of the dust collection system and then be rotated to discharge heavy material  26 . As the airlock chamber rotated to positions not in communication with the entrance hole, then heavy material  26  would accumulate on the outer perimeter of the cylinder until the airlock chamber was once again in communication with the entrance hole to receive the accumulated heavy material  26 . While such an embodiment is not preferred, it is clearly operational.  
      Blades  76  may have a variety of shapes other than rectangular and still perform in accordance with the concept of the invention. One example would be blades that have substantially semi-circular outer perimeter which would form the seal between the blade and inner surface of the blade housing. In such a case, the blade housing would be substantially spherical. Trapezoidal or other shapes may also be used. The rectangular or square shape is simple and allows for the insertion of the blade assembly easily into the blade housing from one side, but other configurations may perform with equal success. In addition, the blades may be angled, including angles that are variable. Innumerable configurations for the blades are imaginable, although blades similar to blades  76  maintain a very simple, effective and cost-efficient configuration.  
      By way of further example, motor  30  need not be electrical, and any power source capable of rotating blades  76  will allow airlock  10  to function. Further, gear box  32  may be eliminated where the power source allows blades  76  to rotate at an appropriate speed.  
      While entrance hole  58  and exit hole  60  are preferably in opposed relation, they need not be, as long as heavy material  26  may enter and exit airlock  10 ,  100  or  200  through these respective holes. Further, entry duct  62  need not extend vertically upwardly as long as heavy material  26  may enter through duct  62 . Likewise, exit duct  68  need not extend vertically downward as long as material  26  may exit properly. Thus, for example, these ducts may be sloped.  
      Airlocks  10 ,  100  and  200  are all situated with blades  76  rotating about a substantially horizontal longitudinal axis  80 . Thus, entrance hole  58  and exit hole  60  are formed in sidewall  45  of airlock  10  and  100  and in an analogous position in airlock  200 . In these configurations, outer edges  86  of blades  76  intermittently communicate with holes  58  and  60  as blades  76  rotate. However, a similar airlock may be situated with a longitudinal axis being substantially vertical. In this configuration, entrance and exit holes may be formed in respective end walls so that ends  88  of blades  76  intermittently communicate with the holes as blades  76  rotate. Entry and exit ducts would then connect the end walls and communicate with respective entrance and exit holes.  
      In the foregoing description, certain terms have been used for brevity, clearness, and understanding. No unnecessary limitations are to be implied therefrom beyond the requirement of the prior art because such terms are used for descriptive purposes and are intended to be broadly construed.  
      Moreover, the description and illustration of the invention is an example and the invention is not limited to the exact details shown or described.