Patent Publication Number: US-7721384-B2

Title: Pneumatic cleaner

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates generally to pneumatic cleaners (vacuums, blowers, etc.), and more particularly to vacuum cleaners that can be worn as a backpack. 
     Over the years, vacuum cleaners and blowers have been adapted for many different uses. Generally, powerful units are large, bulky, and inherently noisy. Interior ducting is commonly used to dampen the noise produced by a motor and internal airflow. This ducting further increases the bulk of a unit. 
     Portability is a common concern. To improve portability, some vacuums or blowers (including those seen in U.S. Pat. Nos. 6,647,586; 6,115,879; 5,040,263; and 4,223,419) have been designed with a strap that can be slung over a user&#39;s shoulder. Others (including those seen in U.S. Pat. Nos. 6,473,933; 6,151,749; 6,066,211; and 4,944,065) have been designed with waist belts. Still others (including those seen in U.S. Pat. Nos. 6,857,163; 6,568,026; 6,553,610; 6,431,024; 6,295,692; 6,073,301; 5,267,371; 4,748,712; 4,658,778; and RE37,081) have been designed to be worn as backpacks. 
     One problem with backpack vacuums is that the size and depth of a quiet, powerful unit can make the unit awkward to carry. 
     BRIEF SUMMARY OF THE INVENTION 
     The applicants have a developed an arrangement that is relatively manageable in size and configuration yet can still provide relatively quiet, powerful operation. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention may be better understood by referring to the accompanying drawings, in which: 
         FIGS. 1 and 2  are isometric views of one form of a backpack vacuum that uses the invention. 
         FIG. 3  is an elevational view from the back of the vacuum of  FIG. 1 , with the harness removed. 
         FIGS. 4 and 5  are opposite elevational side views of the vacuum, again with the harness removed. 
         FIG. 6  is a top view of the vacuum, with the harness removed. 
         FIG. 7  is a sectional view through lines  7 - 7  in  FIG. 3 . 
         FIG. 8  is a side view of a filter cage used in the vacuum. 
         FIG. 9  is a sectional view through lines  9 - 9  in  FIG. 4 . 
         FIG. 10  is a sectional view through lines  10 - 10  in  FIG. 4 . 
         FIG. 11  is a sectional view through lines  11 - 11  in  FIG. 5 . 
         FIG. 12  is a sectional view through lines  12 - 12  in  FIG. 4 . 
         FIG. 13  is a sectional view through lines  13 - 13  in  FIG. 4 . 
         FIG. 14  is a sectional view through lines  14 - 14  in  FIG. 4 . 
         FIG. 15  is an enlarged fragmentary view of one of the latches, taken along the plane of  FIG. 14 . 
         FIG. 16  is a fragmentary view corresponding with  FIG. 15 , but showing the latch in an open position. 
         FIG. 17  is sectional view through lines  17 - 17  of  FIG. 15 . 
     
    
    
     DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT 
       FIGS. 1-6  depict one form of pneumatic cleaner that can be built using the invention. The illustrated cleaner is a vacuum  10 . The vacuum has a tank  12 , a lid assembly  14 , a hose  16 , and a harness  18  that allows the vacuum to be carried as a backpack. 
     The Tank 
     The illustrated tank  12  is a dirt tank with tanks walls  22  (best seen in  FIG. 7 ) that rise from a tank bottom  24  around a tank axis  26  that parallels the front of the tank (the part of the tank that, in use, forms an unhinged panel  27  toward the user&#39;s back). The illustrated tank axis  26  ( FIG. 7 ) is vertical, but it could also be angled with respect to the vertical. The upper edge  30  of the tank lies on a plane  31  that is canted at an angle of approximately 35 degrees with respect to the tank axis  26 . Preferably, the plane  31  is canted at an angle between 25° and 75° degrees with respect to the tank axis  26  and/or to the vertical. In cross section (as can be discerned from  FIG. 6 ), the illustrated dirt tank  12  has a generally oval shape, is approximately 22 inches tall, 12 inches wide, and 8 inches deep, and has an internal tank volume of approximately 900 cubic inches. Other tank configurations could also be used. For example, the tank could take the form of a recovery tank for an extractor, a simple lower housing for a blower, etc. The tank can be made from a variety of materials, including rigid plastic. 
     Air is drawn into the illustrated tank  12  through the hose  16 , which can be connected to the tank by a conventional tank inlet fitting  28 . 
     The Lid Assembly 
     As seen in  FIGS. 4 and 5 , the lid assembly  14  covers the top of the tank  12 . As seen in  FIG. 7 , the illustrated lid assembly  14  includes a filter assembly  40 , a motor assembly  42 , and a lid cover  43 . The lid assembly also includes walls that form a pre-motor airflow path from the filter assembly  40  to the motor assembly  42 , and a post-motor airflow path from the motor assembly to a pair of exhaust vents  44  ( FIGS. 4 and 5 ). Air from the motor assembly can also be delivered through an optional blower duct  45  on the illustrated lid, as described below. The illustrated lid cover  43  is made of rigid plastic, and includes a rim  46  that is configured to mate with the upper edge  30  of the tank  12 . 
     The dimensions of the tank  12  and the lid cover  43  can vary. Along the angled plane  31 , the illustrated rim  46  measures approximately 15 inches wide from front to back; the illustrated lid cover  43  rises approximately 6 inches from the plane of the rim. With the lid assembly  14  attached, the overall unit depth D of the illustrated cleaner  10  (measured horizontally from the plane of the panel  27  near the user&#39;s back to the rearward-most point of the lid cover) is approximately 9 inches. The horizontal distance from the front of the tank to the center of gravity of the cleaner is approximately 4 inches. Other sizes and shapes could also be used. For ease of use, however, the overall unit depth is preferably no more than approximately 12 inches, and the distance from the front of the tank  12  to the center of gravity is no more than approximately 5 inches. 
     When the lid assembly  14  is attached to the tank  12 , the filter assembly  40  is in fluid communication with the internal volume of the tank, and filters the air coming from the tank before the air reaches the motor assembly  42 . Although other arrangements could be used, the illustrated filter assembly  40  includes a lid cage  47  ( FIG. 8 ) on the bottom of the lid assembly  14 . The illustrated lid cage includes a replaceable, cylindrical filter cartridge  48  that fits on a filter cage  49 , but a wide variety of filter options can be used, including filters of other shapes and sizes, bags, cyclone chambers, etc. 
     The Motor Assembly 
     The motor assembly  42  powers the cleaner  10 . The illustrated motor assembly ( FIG. 7 ) is positioned centrally within the lid assembly  14 , and includes a motor  50  and an impeller  52  that spins on a shaft  53 . The illustrated motor is a 5½ horsepower electric motor, though other sizes and types of motors, including a switch reluctance motor, could also be used. Although other arrangements could be used, the illustrated impeller  52  is positioned axially beneath the motor  50 , and is arranged for spinning air outwardly. The illustrated impeller  52  is approximately ⅜ inches high, with an external diameter of approximately 5 inches. The illustrated impeller shaft  53  is mounted at an acute angle with respect to the vertical, perpendicular to the angled plane  31  of the upper edge  30  of the tank  12 . 
     As best seen in  FIGS. 7 and 9 , the air path from the illustrated filter assembly  40  to the illustrated motor assembly  42  includes an inlet chamber  54  defined by walls  55  that extend from a mouth  56  of the filter assembly to an impeller inlet grill  58  on the motor assembly. Preferably, this air path is short and unrestricted. In the illustrated cleaner, the distance from the center of the mouth of the filter assembly  40  to the inlet grill  58  on the motor assembly  42  is approximately 2 inches, and the lateral walls  55  are widely spaced. Although other arrangements could be used, the short distance and wide spacing of the walls helps to keep the flow resistance through this air path relatively low. 
     The Post-Motor Airflow Chambers 
     The air path from the motor assembly  42  to the exhaust vents  44 , on the other hand, is relatively long and tortuous. This arrangement helps to quiet the noise of the cleaner  10 . In the illustrated cleaner, the air path from the motor assembly  42  to the exhaust vents  44  includes a variety of different chambers around the motor assembly. As discussed below, three tangential airflow chambers conduct the air in a tangential direction around the motor assembly. These chambers are divided by shared annular walls (walls that generally extend around the axis of the motor assembly, rather than toward it, and need not extend continuously all the way around the assembly, or be positioned at a constant radius). Collectively, the illustrated tangential chambers direct the air first to the back of the cleaner, then to the front of the cleaner, and then back again to the back of the cleaner, providing a relatively long, tortuous path. 
     As best seen in  FIGS. 10 and 11 , air from the illustrated motor assembly  42  is blown into a first radial chamber  60  that is defined primarily by a first annular wall  62  that is approximately 3 inches high and is spaced approximately ½ inch radially away from the motor assembly. This chamber, which substantially surrounds the motor assembly, diverts the air from the impeller  52  and sends it upwardly. 
     The diverted air enters a second radial chamber  63  ( FIG. 11 ) that is primarily defined by a second annular wall  70  that is approximately 1¼ inches high and is spaced even farther away from the motor assembly  42 . The volume of the illustrated second radial chamber is approximately 12 cubic inches, but could vary in from 10 cubic inches to 14 cubic inches for similar units using other common motor assemblies. In this chamber, the air moves radially outwardly, causing its flow rate to decrease. An upper radial wall  66  requires the air to move downwardly. 
     As seen in  FIGS. 11 and 12 , the downwardly-directed air then enters a first tangential airflow chamber  67  that—in the illustrated cleaner—is positioned radially outwardly from the first radial chamber  60  and substantially surrounds the impeller  52 . This first tangential airflow chamber is defined by the first annular wall  62 , a radial portion  68  of the wall  55  that defines the chamber between the filter assembly  40  and the motor assembly  42 , and a third annular wall  72  that is positioned outwardly from the first annular wall  62 . As seen in  FIG. 12 , this tangential airflow chamber  67  substantially surrounds the motor assembly  42 . In this chamber, air is collected and directed rearwardly, in a tangential direction, to an outlet  74  located near the back of the cleaner. 
     The dimensions of this first tangential airflow chamber  67  can vary. The distances between the annular walls  62 ,  72  of this first tangential airflow chamber can vary from approximately ¾ inches to approximately 2 inches, and the height of those walls can vary from approximately ½ inches to approximately 2 inches. Preferably, the radial cross-sectional area of this chamber  67  will range from approximately 20 square inches to approximately 24 square inches when the illustrated cleaner is used with most conventional motor assemblies in use today. The lateral length of the illustrated chamber, from a forwardmost path position  73  toward the front of the cleaner to the outlet  74  near the back of the cleaner  10  is approximately 9 inches, but the distances between these path positions could vary from approximately 8 inches to approximately 10 inches in comparably-sized products arranged in a similar way with a similar motor assembly. The shortest flow path through this illustrated chamber  67  is approximately 5 inches. The size of the outlet  74  can also vary, from approximately 1 square inch to approximately 5 square inches for similarly-arranged products with a similar motor assembly. 
     As seen in  FIGS. 12 and 13 , after passing through the outlet  74 , air in the illustrated cleaner  10  moves upwardly into a conversion chamber  76 . The path of the air after entering the conversion chamber depends upon whether the device is configured for vacuum use or for use as a blower. 
     For vacuum use, the 2½ inch diameter blower duct  45  on the illustrated lid assembly  12  is closed by a cap  78  ( FIG. 13 ). The presence of the cap forces the air into a pair of lower tangential airflow chambers  80 , where it ultimately proceeds to the exhaust vents  44 , as discussed below. 
     Alternatively, the illustrated cleaner  10  can be configured for use as a blower by first removing the illustrated cap  78  from the blower duct  45 . Then, a hose and fitting similar to the hose  16  and the fitting  28  that feed into the tank  12  can be inserted into the blower duct  45 . The insertion of the fitting can seal off the path from the conversation chamber  76  to the tangential airflow chambers  80  and force the air into the hose. 
     As seen in  FIGS. 11 and 14 , each of the illustrated lower tangential airflow chambers  80  is positioned radially outwardly from first tangential airflow chamber  67 . These lower airflow chambers  80  extend substantially the entire overall unit depth of the cleaner  10 . In these lower chambers, air is re-directed forwardly, again in a tangential direction, from a path position  81  near the conversion chamber  76  ( FIG. 14 ) to a frontal chamber  82  near the front of the vacuum. The illustrated lower airflow chambers  80 , which vary in height from approximately 1½ inches near the conversion chamber  76 , to approximately 2½ inches at the mid-depth of the cleaner, to approximately 2 inches near the front of the cleaner  10 , are defined by the third annular wall  72 , upper and lower radial walls  76  and  78  ( FIG. 11 ), and a fourth annular wall  84  that is spaced approximately ½ inches from the third annular wall. The lateral length of these tangential airflow chambers  80 , from the conversion chamber  76  to the frontal chamber  82 , is approximately 15 inches. This distance exceeds the overall unit depth, but could be varied. 
     As seen in  FIG. 14 , air can leave the frontal chamber  82  in the illustrated cleaner  10  through terminal tangential airflow chambers  86  that extend substantially the entire overall unit depth and lead to the exhaust vents  44  on the back of the cleaner  10 . The terminal airflow chambers  86  are positioned radially outwardly from the lower air chambers  80 . As seen in  FIG. 11 , the illustrated terminal airflow chambers  86  are defined by the fourth annular wall  84  of the lower air chambers  80 , the upper and lower radial walls  76  and  78 , and the outer shell  90  of the lid assembly  12 , which is spaced approximately 1 inch from the fourth annular wall  84 . The illustrated terminal air chambers  86  can vary in height from approximately 1½ inches to approximately 3 inches near the frontal chamber, to from approximately 2 inches to approximately 4 inches at the mid-depth of the cleaner, to from approximately ½ inches to approximately 2 inches near the exhaust vents  44 . The lateral length of these terminal chambers  86 , from the frontal chamber  82  to the exhaust vents, is approximately 14 inches. 
     In the illustrated cleaner  10 , the overall air path from the impeller  52  in the motor assembly  42  to the exhaust vents  44  exceeds 40 inches. Preferably, the overall length of the airflow path from the motor assembly to the exhaust vents is at least 30 inches for cleaners using motor assemblies and arrangements comparable to the one illustrated. 
     Shaft Angle 
     As seen in  FIG. 7 , the impeller shaft  53  and the plane  31  of the lid cover  43  in the illustrated vacuum  10  are canted with respect to the axis  26  of the tank  12  and to the vertical. The various chambers in the lid assembly  12  are generally parallel to the plane  31  of the lid cover  43 . Canting the angle of the impeller shaft  53  and the lid cover  43  reduces the rearward projection of the annular chambers and passages in the lid assembly  14 . As noted above, the linear distance from the back of the frontal chamber  82  in the illustrated cleaner to the outlet  74  on the conversion chamber  76  ( FIG. 14 ) is approximately 15 inches, and the linear distance from the front of the fourth annular wall  82  to the back of the exhaust vents  44  is approximately 11½ inches. However, because of the angle of the impeller shaft  53  and the lid cover  43 , the overall depth of the vacuum  10  (including the blower port  45 ) is only approximately 11 inches, and the center of gravity of the unit is roughly ⅓ closer to the front of the unit (only approximately 4 inches in the illustrated embodiment) than it would have been if the same lid cover  43  and motor assembly  42  were arranged horizontally. Both the reduced overall depth of the unit and the reduced distance from the front of the tank to the center of gravity improve the ease of carrying and maneuvering the vacuum. 
     When the impeller shaft is angled, the overall depth of the unit can also be affected by the proposition of (a) the radial distance from the impeller to the farthest air chambers to (b) the axial height of those chambers. The lower this proportion, the more the impeller may need to be canted to reduce the overall depth of the unit. As can be seen in  FIG. 7 , the ratio of the (a) radial distance to the farthest points in the illustrated conversation chamber  76  and in the frontal chamber  82  to (b) the axial height of those chambers is roughly 2:1. With these proportions, a minimum cant of approximately 35° is required to reduce the overall depth of the unit. Units with distant chambers that are farther away for their height (i.e., that have a higher proportion of radial distance to axial height) may be able to obtain overall depth reductions with less tilt. 
     Arranging the impeller shaft  53  horizontally could minimize the rearward projection of the post-motor airflow chambers. However, pre-motor ducting generally includes an inlet chamber disposed axially below the impeller (like inlet chamber  54  in the illustrated cleaner  10 ), and a strictly horizontal arrangement of the impeller may result in the inlet chamber adding to the overall depth of the unit. Preferably, then, the impeller shaft is inclined sufficiently from the horizontal to prevent the required projection of the inlet chamber from adding to the overall unit depth. In the illustrated vacuum  10 , the inlet chamber  54  will not add to the overall depth of the unit so long as the impeller shaft  53  is not angled more than approximately 70° with respect to the vertical. Steeper angles could be used, however, if the inlet chamber  54  were reconfigured. 
     Other Elements 
     The hose  16  allows the user to direct the suction of the unit to desired locations. Most conventional vacuum hoses can be adapted for use with the illustrated embodiment of the invention. 
     The harness  18  ( FIGS. 1 and 2 ) allows the user to wear the cleaner  10  on his or her back. The illustrated harness  18  includes conventional adjustable shoulder straps  92  and an adjustable waist belt  94 . Many other arrangements could be used. 
     An optional control pad  96  is connected to the illustrated cleaner  10  by a cord  98 . The illustrated control pad allows the user to remotely turn the cleaner on or off, for example, or to control the speed or pressure of the flow of air through the cleaner. 
     As seen in  FIG. 7 , the illustrated vacuum  10  also has an optional motor cooling fan  100  on the motor  50 . Ducting  102  creates a path from cooling-inlets  104  on the lid assembly  14  ( FIG. 6 ) to the cooling fan  100 , and from the cooling fan to cooling outlets  106  on the lid assembly. In the illustrated cleaner, the flow through the cooling air path is completely separate from the working airflow from the tank  12 . Alternatively, filtered air from the tank could be used to cool the motor, as known to those skilled in the art. 
     As seen in  FIGS. 15-17 , latches  108  can be used to secure the lid assembly  14  to the tank  12 . The illustrated latches are mounted on the tank with a pivot  110  ( FIGS. 15 and 16 ) that enables the latch to open and close on the same plane  31  as the upper edge  30  of the tank. When the lid assembly  14  is in place, a lip  112  on the rim  46  ( FIG. 17 ) projects over the side of the tank  12 , preventing lateral movement. When the latch  108  is closed, an arm  114  inside the head  116  of the latch engages the top of the rim  46 , holding the lid assembly  14  securely in place. 
     This description of various embodiments of the invention has been provided for illustrative purposes. Revisions or modifications may be apparent to those of ordinary skill in the art without departing from the invention. The full scope of the invention is set forth in the following claims.