Patent Publication Number: US-2006005345-A1

Title: Hand held steam cleaner

Description:
FIELD OF THE INVENTION  
      This invention relates to a hand held steam cleaner and more particularly to a hand held steam cleaner that has a water container and a pump for delivering water from the container to a tank that is electrically heated to produce steam which is thereafter emitted through a nozzle to an area to be cleaned.  
     BACKGROUND  
      Steam cleaners have been know that have drawn water from a container, converted it to steam and emitted the steam at a nozzle that was equipped to carry one of various cleaning tools such as brushes, wipers, etc. These were often two component arrangements wherein the water container was adapted to rest on the floor where the water is heated and converted to steam that is then delivered through a flexible tube to a cleaning head. The steam then has been delivered through a nozzle on the cleaning head. These devices have been unwieldy and the delivery of steam through a long length of hose raises the possibility of significant condensation of the steam back to water. A similar device equips the water container and steam production unit with a handle so as to be carried by the user from place to place while again a cleaning head is manipulated to emit steam delivered via flexible hose. The device is awkward. Needless to say, if both hands are needed for the cleaning task, a hand is not available to move the water container and steam producing unit. For this reason a strap has been proposed on one such device, but this requires the cumbersome water container and steam producing unit to be strapped to the user&#39;s body. Neither the use of the handle, nor the strapping of the unit to the body addresses the question of increased likelihood of condensation by delivery of steam through the hose attaching the two units.  
      Self contained and hand manipulated steam cleaners have been sold, but they have often been large, bulky and difficult to manipulate. If smaller, some cleaners have contained insufficient water to allow steam cleaning for a reasonable amount of time or have delivered an insufficient flow of steam for proper cleaning. Some have employed a hand operated pump to deliver water to a boiler where steam is created. There is a need, then, for a relatively compact, well-balanced, readily manipulated, single unit hand held steam cleaner that delivers steam at a rate sufficient for most cleaning tasks and over a reasonably long period so that the cleaning need not be often interrupted to replenish water in the cleaner.  
     BRIEF SUMMARY  
      In accordance with this invention a hand held steam cleaner is of a relatively small size, has an easily manipulated pistol shape. When a trigger is depressed to activate a switch the steam cleaner delivers a sustained, relatively high flow of steam over a sufficiently long period to permit few or no interruptions for refilling.  
      In one preferred embodiment the hand held steam cleaner has an electric water pump with a capacity of at least approximately 55 ml per minute and a heated tank that, despite its small size, is able to convert water to steam at that rate and deliver it to the steam cleaner&#39;s nozzle. In a more preferred, exemplary embodiment, the rate of delivery of water to the tank is approximately 70 ml per minute. The tank preferably has an electrical heater coupled in heat conducting relation to a wall thereof. In a preferred embodiment, the interior surface of that tank wall has a surface area increasing topography with numerous surface area increasing projections or undulations such that a large, hot surface area is brought into contact with the water being converted to steam. In that embodiment, baffles formed along the flow of water in the tank define a serpentine path or paths from the tank inlet to the nozzle. This lengthens the path along which heat transfer to the water occurs. In a preferred, exemplary embodiment the tank has the electrical heater imbedded in the wall by casting the tank about the heater. This assures excellent heat transfer from the heater to the tank wall. The tank is preferably cast of a good heat conductor like aluminum.  
      The heater may be a resistive heater and U-shaped. Preferably, two of the serpentine paths extend along the length of the two legs of the U-shaped heater generally parallel to the legs and close to the legs.  
      A water container is detachably connected to a housing that includes a forward barrel and a hand grip. A one way valve, in one preferred embodiment, is formed through a wall of the water container. Two small holes open into the container closely proximate one another. Into one hole is inserted a tack-shaped soft and pliant insert, the head of which is on the interior side and a portion of which overlies the second hole. The head prevents water escaping, but when water is pumped from the container the flexible head of the insert bends away from its underlying hole to permit air entering the container. This makes it possible to continue to pump water. A water line leading from the container to a small electrical pump in the housing includes, within the container, a flexible plastic tube leading to the water outlet of the container. The tube has affixed to a free end a relatively heavy intake element that will bend the tube and locate the inlet element below the level of the water in the container irrespective of the angle or attitude at which the cleaner is held.  
      For safety, the preferred, exemplary embodiment of the invention has a steam release valve that vents hot steam and/or water under pressure to atmosphere in the event of steam pressure buildup. Communicating with a water flow path from the pump to the heated tank is a tube that terminates in a steam release cap extending through a wall of the steam cleaner housing. Tightly held within the tube adjacent to the cap is a metal, preferably stainless steel, ball that is in fluid-type engagement with the interior of the tube. Should it occur that steam pressure builds within the tank and the water delivery path from the pump to the tank as may occur when the unit&#39;s nozzle is blocked, hot steam and/or water under pressure will reach the tube at the location of the ball. The tube is of a thermoplastic and expands under the increased heat and increased pressure to permit steam and/or water to move around the ball and into the cap, escaping to atmosphere thus relieving the pressure buildup. The cap&#39;s inner tip is slotted across so that the ball, if it engages the tip, does not block the passage through the cap.  
      The steam cleaner is conveniently controlled by a trigger-like switch actuator located on the hand grip. It switches electrical power to the pump to cause delivery of water to the heated tank. The temperature of the tank is thermostat controlled. A thermostat is secured in heat conducting relation to the tank wall carrying the heater. The thermostat is operative to break the electrical connection to the heater at a desired temperature. Preferably, breaking this connection also changes the state of an indicator lamp (i.e. from on to off or vice versa), whereby the user is made to know that the tank has reached its optimum temperature and steam cleaning can proceed.  
      In a preferred embodiment, absent the attachment of any cleaning tool at the nozzle, the steam cleaner has only a length of less than approximately 13 inches, a height of less than approximately 8 inches and a width less than approximately 3½ inches. Consequently the steam cleaner is easily manipulated manually.  
      The above and further objects and advantages of the invention will be better understood with reference to the following detailed description taken in consideration with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a perspective view of a hand held steam cleaner in accordance with the present invention;  
       FIG. 2  is a top plan view of the steam cleaner of  FIG. 1 ;  
       FIG. 3  is an enlarged cross-sectional view of the steam cleaner of  FIGS. 1 and 2  taken along the line  3 - 3  in  FIG. 2  with certain interior parts illustrated in elevation;  
       FIG. 4  is an enlarged side elevation view with parts broken away for clarity of a tank and heater for converting water to steam in the steam cleaner of  FIGS. 1 and 2 ;  
       FIG. 5  is a top plan view of the tank of  FIG. 4  with a cover plate removed to reveal the tanks&#39; interior;  
       FIG. 6  is a schematic illustration of the electrical interconnections of the  FIG. 1  steam cleaner;  
      FIGS.  7 ( a ) and ( b ) are perspective views of interfitting nose members and;  
       FIG. 8  is an enlarged fragmentary cross-sectional view of a one-way valve admitting air into the interior of a water container permitting pumping of water from the container; and  
      FIGS.  9 ( a ) and ( b ) are perspective views of interconnecting elements of a water container and body of the steam cleaner of  FIGS. 1 and 2 . 
    
    
     DETAILED DESCRIPTION  
      Turning now to  FIG. 1 , there is shown a hand held steam cleaner  10  in accordance with the present invention. The cleaner is generally pistol shaped and includes a housing  12  that has a barrel section  14  and a hand grip  16 . The housing may, for example, be molded in two halves and held together by screws introduced through holes in one of the halves at suitably chosen locations such as, e.g. the holes  17 . A trigger-like switch actuator  18  is carried by the hand grip. A generally conical nose member  20  is detachably connected to the main housing  12 . The nose member  20  has a central opening  22  in which is located a, preferably brass, nozzle  24 . One of a number of cleaning tools such as brushes, wipers and the like may attach to the nose member in fluid communication with the nozzle  24  as described below. Rearward of the hand grip  16 , a water container  26  detachably connects to the main housing  12 . A slide  28 , best seen in  FIG. 2  and again in  FIG. 9 ( a ), is finger operated to release the container  26  from the housing  12 .  
      As shown in  FIG. 3 , the trigger  18  is biased outward from the hand grip  16  by a spring  30 . When depressed, the trigger  18  closes a switch  32  also shown in the schematic of  FIG. 6 . This closes a circuit from an electrical plug  34  to a pump  36  again as schematically illustrated in  FIG. 6 . The pump  36  in one preferred exemplary embodiment is a commercially available electric pump operating on 120V A.C. at 60 HZ and rated at 70 ml./min. ±20%. A heater  38  is connected to the plug  34  via a thermostat  40  and fuse  42  (in  FIG. 6 ). An indicator lamp  44  (in  FIG. 6 ) in series with a current limiting resistor  46  is connected across the heater  38 .  
      As best seen in  FIG. 4 , the heater  38  is imbedded in a wall  48  of a tank  50 . The tank  50  may be of cast aluminum, molded about the heater  38  for excellent heat transfer from heater to tank wall. The heater  38  may be a resistive “Calrod” type heating element. It is of an extended U shape, running substantially the entire length of the tank  50 . Its two ends and electrical connections thereto can be seen at  52  and  54  in  FIG. 5 . An interior recess  56  within the tank  50  and as shown in  FIGS. 4 and 5  receives water at one end thereof and emits steam from the other. When activated, the pump  36  pumps water through a water inlet tip. The water proceeds along a pair of serpentine paths indicated by the unnumbered arrows in  FIG. 5 . Steam emerges under pressure from a nozzle  60  that threads into a boss  62  integrally formed on the tank  50 . The serpentine paths are defined by a series of side baffles  64  integrally cast into the interior of the tank  50  and a central divider  66  defining further baffles  68 . The serpentine paths provide a longer path to improve heat transfer to water moving along them. Along the entire water to steam conversion paths within the tank  50 , integrally cast, pyramid-shaped projections  70  cover the surface of the bottom wall, increasing the surface area for still better heat transfer to the water introduced into the tank. A plate  72  shown in  FIG. 4  closes the tank. A series of screws (not shown) screw the plate  72  into tight engagement with a gasket  74  seated within the tank  50  as shown in  FIG. 5 . Screw holes  76  are provided in bosses within the tank to receive the screws holding the plate  72  in place. A thermal blanket  78  in  FIG. 3  is wrapped about the tank  50  and may be secured by a fiber tie wound around and tying the blanket in place (not shown) or by other convenient means.  
      Tank  50  is supported in the housing by a suitably sized flange  80  molded as part of the housing and engaging a silicon rubber washer  82  received on the boss  62  at the front of the tank. A pair of cruciform projections  93  are integrally cast on the tank  50  opposite sides thereof. These receive a further pair of silicon rubber washers  95  (one of which is shown in  FIG. 3  and  FIG. 5 ). The holders  95  fit into a pair of sockets (not shown) integrally molded with the sides of the housing  12  to support the tank  50  at its back end.  
      When the pump  36  is activated, water flow out of the container  26  through the pump and to the tank  50  begins at a spherical water intake element  84 . The element  84  has a tubular extension  86  that enters a long, flexible plastic tube  88  of, for example, silicon rubber. The tube  88  connects to an inwardly directed projection  90  of a water container cap  92 . The cap has a cylindrical skirt  94  that fits into a water container opening  96 . The skirt  94  carries a washer like seal of, again, silicon rubber or other soft plastic material capable of sealing engagement between the edge of the container opening  96  and a head  100  of the cap  92 . An outward projecting hollow tubular part  102  of the cap  92  is in fluid communication with the inward directed projection  90 . The hollow member  102  extends into a rubber seal  104  when the container  26  is mounted to the steam cleaner housing  12 . The seal  104  extends through a rear wall  106  of housing  12 . At its forward end the seal, which is hollow, connects onto a cylindrical inlet  108  of the pump  36 . The intake element  84 , tube  88 , cap  92  and seal  104  thus form a first water flow line from the container to the pump. The spherical intake element  84  in the container  26  is of a material, brass for example, that is heavy enough to bend the tube as gravity keeps the element  84  at or near the bottom of the pool of water in the container regardless of the attitude of the steam cleaner. The element  84  may have a number of openings from the surface to the extension  86  as illustrated.  
      The pump  36  has a cylindrical outlet  110 . Onto it fits a flexible plastic sleeve  112 . The sleeve  112  extends onto a 3-way tube  114 . The 3-way tube opens into the sleeve  112  in one direction and into a further sleeve  116  in the opposite direction. The sleeve  116  fits onto a steam release cap  118  that opens through a wall of the housing  12 . Tightly received in the sleeve  116  adjacent the internal end of the relief cap  118  is a stainless steel ball  120 . A further branch of the 3-way tube  114  receives a flexible plastic tube  122 . That tube extends to the water inlet tip  58  of the tank  50 . The sleeve  112 , 3-way tube  114  and tube  122  form a second water flow line from the pump to the tank.  
      In the event that steam pressure rises beyond an acceptable level in the tank  50 , as may occur if the nozzle  60  is blocked, steam backs up through the tube  122 , the 3-way tube  114  and the sleeve  116 . There, pressure and heat effects enlargement of the thermoplastic sleeve  116  such that hot steam and/or water under pressure is able to flow past the ball  120 . The inward tip of the steam relief cap  118  is slotted across at  124  so that the ball  120  does not block entrance of the steam into the cap. In this way overpressure within the steam cleaner is relieved.  
      The nose member  20  of the steam cleaner ( FIGS. 3 and 7 ( a )) has integrally molded and slightly flexible connectors  126  whose outwardly turned ends snap into place through holes formed in a front wall  128  of the housing  12 . As shown in FIGS.  7 ( a ) and  7 ( b ) the nose element  20  has a hollow interior. A generally circular opening  22  has radially opposite slots  130  and  131 , the slot  134  being slightly wider than the slot  130 . This difference in widths assures proper insertion into the opening of one of several cleaning tools such as the brush  136  of  FIG. 7 ( b ). These tools have a stem  138  and a pair of radially opposite projections  140  and  142 , the projection  142  being slightly wider than the projection  140  such that it will fit only in the slot  134  and not in the slot  130 . Inside the tip  20  integrally molded raised surfaces permit the tool or brush  136  to be turned to its proper orientation with the projection  142  seated on a first land  144  and the projection  140  seated on a somewhat narrower second land  146 . A pair of heightened wall segments  148  and  150  prevents turning the tool or brush  136  towards the wrong orientation. Ends of the heightened wall segments  148  and  150  define edges of the lands  144  and  146 , respectively, along with a pair of slightly raised bosses  152  and  154 .  
      Shown in  FIG. 8  is the one way air inlet valve arrangement of the container  26 . A slightly recessed circular section  156  of the forward wall of the container has formed therein a pair of closely spaced openings  158  and  168 . A tack-shaped insert  162  of pliant plastic or rubber extends through the hole  158  where it is tightly retained. The head  164  overlies the opening  160 . When water is pumped from within the container  26 , air pressure against the head  164  of the tack-shaped insert  162  causes the head to bend away from the opening  160  as illustrated in  FIG. 8 . This permits the introduction of air allowing liquid to be pumped from the container  26 .  
      The means for connecting the container  26  with the housing  12  is shown in  FIG. 9 . The container  26  has a pair of slots  170  that interfit with a pair of guiding ribs  172  formed on the interior of the sides of the housing  12 . These lead the end face  174  of the container to face the opposing end face  176  of the housing  12 . This brings the cap  92  to the seal  104 . The rim  174  of the housing  12  aligns with a shoulder  176  on the container  26 . At the same time a protruding catch member  178  on the container  26  moves into a recess  180  in the housing  12 . A slidable latch  180  connected to the slide  28  is spring biased to its position projecting from a box  182  formed in the housing  12 . The box  182  contains a small coil spring urging the latch outward. The surface of the latch engages a beveled surface  184  on the catch and is cammed back into the box  182  as the latch moves to alignment with a shallow slot  186  into which it snaps, retaining the container  26  in place on the housing  12 .  
      Although preferred embodiments of the invention have been described in detail, it will be readily appreciated by those skilled in the art that further modifications, alterations and additions to the invention embodiments disclosed may be made without departure from the spirit and scope of the invention as set forth in the appended claims.