Abstract:
The present invention provides a liquid spray gun with several improved features, including (1) a molded polymeric possibly disposable body assembly through which passes liquid sprayed by the spray gun that is manually releasable from a metal platform portion of the spray gun through which air is fed to passageways through the body assembly to spray the liquid; (2) non-cylindrical air passageways on air horns that provide improved shape and uniformity for the wide elongate stream of liquid formed by the spray gun, and (3) an air cap portion of the body assembly mounted for manual rotation on a nozzle portion of the body assembly between positions defined by stops and retained at those positions by friction.

Description:
FIELD OF THE INVENTION  
       [0001]     This invention relates to liquid spray guns of the type comprising a body assembly including a nozzle portion having a liquid passageway extending to an outlet end opening through an outlet end of the nozzle portion, the body assembly having a first air passageway having an outlet end at the outlet end of the nozzle portion that extends around the outlet end of the liquid outlet passageway and is shaped to direct air under greater than atmospheric pressure against liquid flowing out of the outlet end of the liquid outlet passageway to propel the liquid away from that outlet end while shaping the liquid into a generally conical stream about an axis; the body assembly including horns projecting past the outlet end of the nozzle on opposite sides of the axis, and also having a second air passageway extending to outlet passageways and apertures spaced along the horns from the outlet end of the nozzle portion and facing opposite sides of the axis, which outlet passageways and apertures direct air under greater than atmospheric pressure flowing through the second air passageway against opposite sides of the stream of liquid formed by air flowing through the first air passageway to reshape that stream into a wide elongate stream; the liquid spray gun further including a platform portion having through air distribution passageways including an inlet opening adapted to be connected to a supply of air under greater than atmospheric pressure, first and second air outlet openings, means for separately regulating the flow of air through the first and second air outlet openings of the air distribution passageways, and manually operated means for stopping or allowing flow of air through the outlet openings of the air distribution passageways; and the platform portion and the nozzle portion having means for mounting the nozzle portion on the platform portion with the first and second air outlet openings of the air distribution passageways communicating with inlet ends of the first and second passageways.  
       BACKGROUND OF THE INVENTION  
       [0002]     The prior art includes liquid spray guns of the type comprising a body assembly including a nozzle portion having a liquid passageway extending to an outlet end opening through an outlet end of the nozzle portion, the body assembly having a first air passageway extending to an outlet end at the outlet end of the nozzle portion that extends around the outlet end of the liquid outlet passageway and is shaped to direct air under greater than atmospheric pressure against liquid flowing out of the outlet end of the liquid outlet passageway to propel the liquid away from that outlet end while shaping the liquid into a generally conical stream about an axis; the body assembly including horns projecting past the outlet end of the nozzle on opposite sides of the axis, and also having a second air passageway extending to outlet passageways and apertures spaced along the horns from the outlet end of the nozzle portion and facing opposite sides of the axis, which outlet passageways and apertures direct air under greater than atmospheric pressure flowing through the second air passageway against opposite sides of the stream of liquid formed by air flowing through the first air passageway to reshape that stream into a wide elongate stream; the liquid spray gun further including a platform portion having through air distribution passageways including an inlet opening adapted to be connected to a supply of air under greater than atmospheric pressure, first and second air outlet openings, means for separately regulating the flow of air through the first and second air outlet openings of the air distribution passageways, and manually operated means for stopping or allowing flow of air through the outlet openings of the air distribution passageways; and the platform portion and the nozzle portion having means for mounting the nozzle portion on the platform portion with the first and second air outlet openings of the air distribution passageways communicating with inlet ends of the first and second passageways. U.S. Pat. No. 5,090,623 (Burns et al.); U.S. Pat. No. 5,102,051 (Smith et al); U.S. Pat. No. 5,209,405 (Robinson et al); and U.S. Pat. No. 5,322,221 (Anderson) and U.S. Patent Application Publication No. U.S. 2002/0148910 A1 published Oct. 17, 2002, provide illustrative examples. In the spray guns described in those U.S. patents typically the nozzle portions can be removed from the platform portions, however the means for mounting the nozzle portions on the platform portions includes attachment members such as threaded nuts that must be removed with a tool such as a wrench, thereby adding difficulty to that removal process.  
       DISCLOSURE OF THE INVENTION  
       [0003]     The present invention provides a liquid spray gun generally of the type described above that is more easily disassembled between successive uses.  
         [0004]     According to the present invention there is provided a liquid spray gun comprising a body assembly including a nozzle portion having a liquid passageway extending to an outlet end opening through an outlet end of the nozzle portion, the body assembly having a first air passageway extending to an outlet end at the outlet end of the nozzle portion that extends around the outlet end of the liquid outlet passageway and is shaped to direct air under greater than atmospheric pressure against liquid flowing out of the outlet end of the liquid outlet passageway to propel the liquid away from that outlet end while shaping the liquid into a generally conical stream about an axis; the body assembly including horns projecting past the outlet end of the nozzle on opposite sides of the axis, and also having a second air passageway extending to outlet passageways and apertures spaced along the horns from the outlet end of the nozzle portion and facing opposite sides of the axis, which outlet passageways and apertures direct air under greater than atmospheric pressure flowing through the second air passageway against opposite sides of the stream of liquid formed by air flowing through the first air passageway to reshape that stream into a wide elongate stream; the liquid spray gun further including a platform portion having through air distribution passageways including an inlet opening adapted to be connected to a supply of air under greater than atmospheric pressure, first and second air outlet openings, means for separately regulating the flow of air through the first and second air outlet openings of the air distribution passageways, and manually operated means for stopping or allowing flow of air through the outlet openings of the air distribution passageways; and the platform portion and the nozzle portion having manually releasable means (i.e., means manually operable by a person without the use of tools) for mounting the nozzle portion on the platform portion with the first and second air outlet openings of the air distribution passageways communicating with inlet ends of the first and second passageways.  
         [0005]     The manually operable means for releasably mounting the nozzle portion on the platform portion can comprise the platform portion including a support wall, an opening through the support wall between inner and outer surfaces of the support wall, and the nozzle portion including a projection from a contact surface on the side of the nozzle portion opposite its outlet end, the projection being received in the support wall opening with the contact surface against the outer surface of the support wall, and a distal part of the projection projecting past the outer surface of support wall, the distal part of the projection having a transverse groove, and the manually operable means further including a latching member releasably engaged in the transverse groove adapted for manual removal from the distal part.  
         [0006]     The platform portion can be reusable (i.e., made of metal), and the nozzle and air cap portions can be molded of a polymeric material. The molded air cap and nozzle portions can be sufficiently inexpensive that they can be discarded rather than cleaned for some applications.  
         [0007]     The passageways on the horns opening through the outlet apertures that direct high velocity air flowing through the second air passageway against opposite sides of a stream of liquid formed by air flowing through the first air passageway to reshape that generally conical stream of liquid into a wide elongate stream can have a greater width in a direction at a right angle to the axis than depth in a direction parallel to the axis (e.g., the outlet apertures can be generally rectangular). Such a shape has been found to form a liquid stream that is very uniform in width and in the amount of liquid delivered per unit time along its length to facilitate uniform application of the liquid to a surface.  
         [0008]     The body assembly can include an air cap including the horns that is molded of polymeric material, with the non-circular passageways leading to the outlet apertures being formed during the molding process. Means are provided for mounting the molded polymeric air cap portion on the nozzle portion, with the molded air cap and the nozzle portion having surfaces forming the first and second air passageways.  
         [0009]     The means mounting the air cap portion on the nozzle portion can allow rotation of the air cap portion about the axis relative to the nozzle portion, the air cap and nozzle portions can include stops limiting relative rotation of the air cap portion relative to the nozzle portion to rotation through a predetermined angle (e.g., 90 degrees) between first and second relative positions, and the means mounting the air cap portion on the nozzle portion can include surfaces in frictional engagement to restrict relative rotation of the air cap and nozzle portions until a predetermined torque is manually applied between the air cap and nozzle portions. Thus a person wishing to change the relative position of the air cap portion on the nozzle portion need only rotate the air cap portion relative to the nozzle portion, and the air cap portion will remain in that position until it is again repositioned by the operator. 
     
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0010]     The present invention will be further described with reference to the accompanying drawings wherein like reference numerals refer to like or corresponding parts throughout the several views, and wherein:  
         [0011]      FIG. 1  is a side view of a liquid spraying device according to the present invention  
         [0012]      FIG. 2  is an opposite side view of the liquid spraying device of  FIG. 1  in which a nozzle portion, an air cap portion and a platform portion of the spraying device are separated from each other;  
         [0013]      FIG. 3  is an enlarged front view of the platform portion of the liquid spraying device as seen along line  3 - 3  of  FIG. 2 ;  
         [0014]      FIG. 4  is a enlarged fragmentary vertical cross sectional view of the liquid spraying device of  FIG. 1 ;  
         [0015]      FIG. 5  is a sectional view taken approximately along line  5 - 5  of  FIG. 4  after the nozzle portion is removed from the platform portion;  
         [0016]      FIG. 6  is a sectional view taken approximately along line  6 - 6  of  FIG. 4  after the nozzle portion is removed from the platform portion;  
         [0017]      FIG. 7  is a side view of the platform portion of the liquid spraying device of  FIG. 1  which has been partially sectioned to show detail;  
         [0018]      FIG. 8  is a rear view of the nozzle portion included in the spraying device of  FIG. 1 ;  
         [0019]      FIG. 9  is a sectional view taken approximately along line  9 - 9  of  FIG. 8 ;  
         [0020]      FIG. 10  is a front view of the nozzle portion of  FIG. 2 ;  
         [0021]      FIG. 11  is an enlarged rear view of the air cap portion included in the spraying device of  FIG. 1 ;  
         [0022]      FIG. 12  is a sectional view taken approximately along line  12 - 12  of  FIG. 11 ;  
         [0023]      FIG. 13  is a sectional view taken approximately along line  13 - 13  of  FIG. 12 ; and  
         [0024]      FIGS. 14, 15 ,  16 , and  17  are enlarged illustrations of alternative shapes that could be used for outlet passageways and apertures in horns on the air cap portion included in the spraying device of  FIG. 1 . 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0025]     Referring now to the drawing there is illustrated a liquid spraying device or spray gun  10  according to the present invention. Generally, the liquid spray gun  10  comprises a body assembly  12  including a nozzle portion  14  with an outlet end  15 . The nozzle portion  14  has a liquid passageway  16  extending from an inlet end  17  to an outlet end  18  opening through the outlet end  15  of the nozzle portion  14 . The body assembly  12  also has a first air passageway  20  extending from an inlet end  21  to an outlet end  22  at the outlet end  15  of the nozzle portion  14 . The outlet end  22  of the first air passageway  20  extends around the outlet end  18  of the liquid passageway  16  and is shaped to direct air under greater than atmospheric pressure against liquid flowing out of the outlet end  18  of the liquid passageway  16  to propel liquid flowing out of the liquid passageway  16  away from the outlet end  15  of the nozzle portion  14  while shaping the liquid into a generally conical stream about an axis  23 . The body assembly  12  includes horns  24  projecting past the outlet end  15  of the nozzle portion  14  on opposite sides of that axis  23 , and the body assembly  12  has a second air passageway  26  extending from an inlet end  27  through portions of the horns  24  to outlet passageways  28  having outlet apertures spaced along the horns  24  from the outlet end  15  of the nozzle portion  14  and facing opposite sides of the axis  23 . The outlet passageways  28  and apertures are non-circular and are shaped to direct air under greater than atmospheric pressure flowing through the second air passageway  26  against opposite sides of a generally conical stream of liquid formed by air flowing through the first air passageway  20  to reshape that generally conical stream of liquid into a wide elongate stream. The outlet passageways  28  and apertures are generally rectangular and have a greater width in a direction at a right angle to the axis  23  than depth in a direction parallel to the axis.  
         [0026]     As a non-limiting example, as illustrated the outlet passageways  28  and apertures can comprise first and second pairs  28   a  and  28   b  of opposed outlet passageways  28  and apertures on the horns  24 , the first pair of outlet passageways  28   a  and apertures each having a width in a direction at a right angle to the axis  23  of about 0.154 inch or 0.39 cm, a depth in a direction parallel to the axis  23  of about 0.35 inch or 0.89 cm, and being spaced about 0.25 inch or 0.64 cm from the outlet end  15  of the nozzle portion  14 , with the outlet passageways  28   a  being disposed at an angle of about 66 degrees with respect to the axis; and the second pair of outlet passageways  28   b  and apertures each having a width in a direction at a right angle to the axis  23  of about 0.165 inch or 0.42 cm, a depth in a direction parallel to the axis of about 0.050 inch or 0.13 cm, and being spaced about 0.35 inch or 0.89 cm from the outlet end  15  of the nozzle portion  14  with the outlet passageways  28   b  being disposed at an angle of about 75 degrees with respect to the axis  23 .  
         [0027]     The body assembly  12  includes an air cap portion  30  including the horns  24  that is preferably molded of a polymeric material (e.g., polypropylene, polyethylene, or glass filled nylon), with the outlet passageways  28  and apertures being formed by the molding process. The body assembly  12  also includes means for mounting the air cap portion  30  on the nozzle portion  14  so that adjacent surfaces of the air cap portion  30  and the nozzle portion  14  form parts of the first and second air passageways  20  and  26 . The means mounting the air cap portion  30  on the nozzle portion  14  includes a radially outwardly projecting annular ring  32  around the outlet end  15  of the nozzle portion  14  co-axial with the axis  23 , and a generally cylindrical collar  33  on the air cap portion  30  having an annular recess  34  from its inner surface adapted to receive the annular ring  32  of the nozzle portion  14 . The collar  33  on the air cap portion  30  is sufficiently resiliently flexible that the inner surface of the collar  33  can be pressed over the annular ring  32  to position the ring  32  in the recess  34 . A cylindrical part  35  of the inner surface of the air cap portion has a close sliding fit around an outer surface of a cylindrical portion  37  of the nozzle portion  14  to separate the first and second air passageways  20  and  26 . This means for mounting the air cap portion  30  on the nozzle portion allows rotation of the air cap portion  30  about the axis  23  relative to the nozzle portion  14 . The air cap and nozzle portions  30  and  14  include stops  36  and  38  respectively that limit relative rotation of the air cap and nozzle portions  30  and  14  to rotation through a predetermined angle (90 degrees as illustrated) between first and second relative positions. This means mounting the air cap portion  30  on the nozzle portion  14  also includes surfaces on the air cap and nozzle portions  30  and  14  in frictional engagement (i.e., such engagement can be with each other as illustrated or, alternatively, could be with a frictional layer, not shown, between the air cap and nozzle portions  30  and  14 ) to restrict relative rotation of the air cap and nozzle portions  30  and  14  until a predetermined torque is manually applied between the air cap and nozzle portions  30  and  14 . That predetermined torque should be enough to restrict rotation of the air cap portion  30  on the nozzle portion  14  by slight contact with the air cap portion, but not so much that it is difficult to manually rotate the nozzle portion  14  on the air cap portion  30 . Such torque should thus be in the range of 5 to 40 inch pounds, and more preferably in the range of 10 to 20 inch pounds. An O-ring  39  is positioned between the air cap and nozzle portions  30  and  14  to restrict leakage between the collar  33  and the nozzle portion  14 .  
         [0028]     The outlet end  22  of the first air passageway  20  is shaped to direct a peripheral portion of air exiting the first air passageway  20  in a converging conical pattern (e.g., converging at an angle in the range of about 30 to 45 degrees with respect to the axis  23  against liquid exiting the outlet end  18  of the liquid passageway  16 . This converging conical pattern better atomizes the liquid leaving the outlet end  18  of the liquid passageway  16  than would air flowing out of the outlet end  22  of the first air passageway  20  in a direction parallel to the stream of fluid leaving the outlet end  18  of the liquid passageway  16 .  
         [0029]     The liquid spray gun  10  further includes a platform portion  40  including a frame  41  having through air distribution passageways including an inlet passageway  42  (see  FIGS. 3 and 7 ) with an inlet end  45  adapted to be connected to a supply of air under greater than atmospheric pressure, first and second air outlet openings  43  and  44 , means in the form of an adjustable valve member  46  for regulating the portion of air flow through the air distribution passageways that can flow to the second air outlet opening  44 , and manually operated valve means  47  for stopping or allowing flow of air from the inlet passageway  42  to the outlet openings  43  and  44  of the air distribution passageways. The platform portion  40  and the nozzle portion  14  have manually operable means for releasably mounting the nozzle portion  14  on the platform portion  40  with the first and second air outlet openings  43  and  44  of the air distribution passageways communicating with the inlet ends  21  and  27  of the first and second air passageways  20  and  26  respectively. That manually operable means (see  FIG. 4 ) comprises the platform portion  40  including a support wall  48  having opposite inner and outer surfaces  49  and  50 , a cylindrical opening  51  through the support wall  48  between its inner and outer surfaces  49  and  50 ; and the nozzle portion  14  including a projection  52  beyond a contact surface  53  on the side of the nozzle portion  14  opposite its outlet end  18 . The projection  52  is received in the opening  51  through the support wall  48  with the contact surface  53  against its outer surface  50  and a distal part of the projection  52  projecting past the inner surface  49  of the support wall  48 . The distal part of the projection  52  has a transverse annular groove  56 , and the manually operable means further includes a plate-like latch member  55  mounted on the frame  41  for sliding movement transverse of the opening  51  between (1) an engaged position at which a generally C-shaped portion of the latch member  55  having a latching surface  55   a  facing away from the support wall  48  that is about normal to the axis of the opening  51  will be positioned in a portion of the transverse groove  56  if the projection  52  is fully engaged in the opening  51  to retain the projection  52  and thereby the nozzle portion  14  in engagement with the platform portion  40 , and (2) a release position to which the latch member  55  can be manually slid against the bias of a spring  54  between the latch member  55  and the frame  41  that biases the latch member  55  to its engaged position, at which release position a circular opening  55   c  through the latch member  55  larger in diameter than the projection  52  is aligned with the projection  52  to allow the nozzle portion  14  to be mounted on or removed from the platform portion  40 . The latch member  55  includes a cam surface  55   b  on its side opposite the latching surface  55   a  that faces the support wall  48  and is disposed at an angle (e.g., about 45 degrees) with respect to the axis of the opening  51  so that pressing the distal end of the projection  52  against the cam surface  55   b  will cause the latch member  55  to move to its release position and allow the distal end of the projection  52  to move past the latch member  55  until the projection  52  is fully engaged in the opening  51 , whereupon the latching surface  55   a  will move into engagement with a portion of the transverse groove  56  (the latching position of the latch member  55 ) under the influence of the spring  54  to retain the projection  52  and thereby the nozzle portion  14  in engagement with the platform portion  40 .  
         [0030]     The platform portion  40  can be made by modifying a metal spray gun that is commercial available under the trade designation “HVLP Gravity feed spray gun” from Graco, Minneapolis, Minn., by adding to the frame  41  a portion  41   a  for mounting the latch member  55  described above and by adding to the frame  41  a plate  58  which provides the outer surface  50  shaped for sealing engagement with the contact surface  53  on the nozzle portion  14 , and in which the first and second air outlet openings  43  and  44  are formed. The second air outlet openings  44  are defined by sockets adapted to closely receive projecting tubular portions  59  that are at the inlet ends  27  of the second air passageways  26  in the nozzle portion  14 . The plate  55  has an opening  71  adapted to closely receive a projection  57  on the nozzle portion  14  to help locate the nozzle portion  14  on the plate  58 , and has a groove  69  around its periphery adapted to receive in sealing engagement a projecting lip  68  around the periphery of the nozzle portion  14 .  
         [0031]     The manually operated valve means  46  (see  FIG. 7 ) for stopping or allowing flow of air from the inlet passageway  42  to the outlet openings  43  and  44  of the air distribution passageways includes a valve seat on the frame  41  around an opening  60  between the inlet passageway  42  and a second air passageway  61  included in the air distribution passageways that is parallel to the inlet passageway  42 . The valve member  62  is mounted on the frame  41  for movement between (1) a closed position engaging that seat to prevent flow of air through the opening  60  to which closed position the valve member  62  is biased by a spring  63  between the valve member  62  and the frame  41 , and (2) positions spaced from the seat around that opening  60  to allow various rates of air to flow from the inlet passageway  42  to the second air passageway  61 , and from there to the first outlet openings  43  and to the second outlet openings  44  if the valve member  46  is open. Such movement of the valve member  62  to positions spaced from the seat can be caused by manually pulling a trigger member  64  pivotally mounted on the frame  41  by a pin  65  toward a handle portion  66  of the frame  41 . The amount of such movement that can be caused by pulling the trigger member  64  is determined by a stop member  67  in threaded engagement with the frame  41  so that the maximum amount of such movement is adjustable. A fluid flow control needle  70  is attached to the valve member  62 . The fluid flow control needle  70  extends through a central bore  72  in the projection  52  and through a seal  74  in the bore  72  around its periphery which separates part of the liquid passageway  16  adjacent its outlet end  18  from the opposite end of that bore  72  (see  FIG. 4 ). A generally conical end portion  75  of that needle  70  is positioned against the inner surface of and closes the liquid passageway  16  adjacent its outlet end  18  when the valve member  62  is positioned in its closed position to which it is biased by the spring  63 . The end portion  75  of that needle  70  moves away from the inner surface of the liquid passageway  16  to allow liquid to flow through it when the trigger member  64  is manually moved toward the handle portion  66  and away from its closed position against the bias of the spring  63 . The end portion  75  of the needle is formed of polymeric material and tapered at a much smaller angle than the valve member  62  so that the valve member  62  will open to allow air to flow through the outlet openings  43  and  44  of the air distribution passageways, through the first and second air passageways  20  and  26 , out of the outlet end  22  of the first air passageway  20 , and out of the outlet passageways  28  of the second air passageway  26  (if the valve member  46  is open) before fluid can flow out of the outlet end  18  of the liquid passageway  16 .  
         [0032]     Liquid can be gravity fed to the outlet end  15  of the liquid passageway  16  from a suitable container at its inlet end  17 , which container could be the container described in U.S. Pat. No. 6,588,681 that includes a portion of a connector adapted for manually releasable engagement with a connector portion  80  illustrated about the inlet end  17  of the liquid passageway  16 . Alternatively, smaller volume liquid containers such as those described in U.S. patent application Ser. No. 10/112,182 (Schwartz), filed Mar. 28, 2002 could be used.  
         [0033]     Optionally, a pressure tap  77  (see  FIG. 2 ) communicating with the second air passageway  26  and closed when not used could be provided to supply air pressure to the pressurized liquid container described in U.S. patent application Ser. No. 10/279,518, filed Oct. 24, 2002, which pressurized liquid container could be used to supply liquid to the liquid passageway  16  of the spray gun  10 . The pressure tap  77  should communicate with the second air passageway  26  at a position spaced (e.g. over 1 inch or 2.54 cm) from the outlet passageways  28  and outlet apertures in the air horns  24  so that it does not cause air pressure differences between the two horns  24 .  
         [0034]     The content of the aforementioned U.S. Pat. No. 6,588,681 and U.S. Applications Nos. 10/112,182 and 10/279,518 are hereby incorporated herein by reference.  
         [0035]     The body assembly  12  including both the nozzle portion  14  and the air cap portion  30  can be molded of a suitable polymeric material (e.g., polypropylene, polyethylene, or glass filled nylon). The body assembly  12 , and particularly its nozzle portion  14  will make most of the contact with a liquid (e.g., paint) being sprayed (i.e., only the needle  70  on the platform portion  40  will contact that liquid), and the molded body assembly  12  can be sufficiently inexpensive that it can be discarded rather than being cleaned for some applications.  
         [0036]     The present invention has now been described with reference to one embodiment and possible modifications thereof. It will be apparent to those skilled in the art that many changes can be made in the embodiments described without departing from the scope of the present invention. For example, the outlet passageways  28  and apertures in the air horns  24  that have a greater width in a direction at a right angle to the axis  23  than depth in a direction parallel to the axis  23  could have shapes other than rectangular, such as, but not limited to, oval shapes  28   a  and  28   b  illustrated in  FIGS. 14 and 15 , diamond shapes such as the diamond shape  28   c  illustrated in  FIG. 16 , or shapes with an enlarged (e.g., generally circular, rectangular or oval) center portions and with more narrow portions extending on opposite sides of the center portion such as the shape  28   d  illustrated in  FIG. 17 . Thus, the scope of the present invention should not be limited to the structures and methods described in this application, but only by the structures and methods described by the language of the claims and the equivalents thereof.