Abstract:
There is provided an airless spray gun housing for an airless spray gun adapted to hydraulically atomize and spray paint wherein the spray gun housing includes a barrel portion and a handle portion, the spray gun housing being a unitary construction wherein the barrel portion and handle portion are integral with each other so that no joint or seam exists between the barrel portion and the handle portion.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates generally to hydraulically operated or airless paint spray guns and, more particularly, it relates to an improved airless spray gun housing which simplifies the construction of the spray gun and decreases the spray gun&#39;s potential to leak during use thus rendering the spray gun more practicable and safer to use. 
       BACKGROUND OF THE INVENTION 
       [0002]    Hydraulic or airless paint spray guns operate on the principle of creating a paint spray pattern suitable for painting by passing paint at high pressure through a small orifice or nozzle disposed at the forward end of the spray gun resulting in atomization of the paint. The pressure at which such spray guns operate is generally about 3000 psi and can be as high as 7500 psi. Obviously, at such high operating pressures, the possibility of leakage at any of the joints in the apparatus is always present. Furthermore, any such leaks can pose a physical danger to the operator of the spray gun because of the high pressure involved. 
         [0003]    Heretofore, airless paint spray gun housings have been constructed in essentially two pieces, a barrel portion and a handle portion connected to the barrel portion. The barrel portion of the spray gun includes a spray tip at its forward end, a longitudinal passageway for delivering the high pressure paint to the spray tip, and means within the passageway operated by a trigger for controlling the volume and extent of the paint spray emitted by the spray tip or nozzle. The handle portion is attached, usually by means of threaded engagement, to a lower part of the barrel portion so as to be gripped by the painting operator whereby to direct the paint spray and operate the trigger. The high pressure paint is generally introduced to the spray gun by means of a high pressure hose connected by means of a swivel coupling to the lower end of the handle. The high pressure paint passes through an elongated filter in the handle and is directed to the passageway in the barrel portion and thus to the spray tip or nozzle. Access to the filter for service or replacement, is gained by removal of the handle portion from the barrel portion for most designs. 
         [0004]    It can be easily understood that, because of the extremely high pressure involved, any joint or coupling in the paint delivery system is highly susceptible to leakage. Likewise, it can be appreciated that the elimination of any joint or coupling in the paint delivery system eliminates any possibility of leakage thereat. 
       SUMMARY OF THE INVENTION 
       [0005]    It is a primary object of the present invention to provide an improved airless paint spray gun which is simpler in design and less likely to leak the high pressure paint passing therethrough and is thus more practicable and effective than heretofore. 
         [0006]    The above object is accomplished in accordance with the present invention by providing an airless paint spray gun wherein the barrel portion and handle portion of the spray gun body or housing are formed integrally or in one piece. The barrel portion of the spray gun housing is provided with a passageway terminating in a spray tip or nozzle at the distal end of the barrel portion and the handle portion is provided with a passageway intersecting the passageway in the barrel portion. The passageway in the handle portion houses an elongated filter for the paint passing therethrough and communicates with a source of high pressure paint. Thus, by constructing the spray gun housing in one piece, the resulting spray gun is simpler in construction and the joint or seam between the barrel portion and the handle portion is eliminated thereby eliminating the possibility of leakage thereat. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    The present invention will be described and understood more readily when considered together with the accompanying drawings in which: 
           [0008]      FIG. 1  is a side elevational view of an airless paint spray gun according to the prior art; 
           [0009]      FIG. 2  is a cross sectional view of the prior art airless paint spray gun of  FIG. 1 ; 
           [0010]      FIG. 3  is an exploded view of another prior art airless paint spray gun; 
           [0011]      FIG. 4  is a cross sectional view of an airless paint spray gun incorporating the one piece paint spray gun housing according to the present invention; 
           [0012]      FIG. 5  is a cross sectional view of the one piece airless paint spray gun housing according to the present invention; and 
           [0013]      FIG. 6  is an exploded view of the airless paint spray gun of  FIG. 4 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0014]    Now turning to the drawings, there is shown in  FIG. 1  a typical prior art airless paint spray gun, designated  110 , wherein the housing  112  includes a barrel portion  114  and a handle portion  116 . At the distal end of barrel portion  114 , a spray tip or nozzle  118  including a tip guard  120  (shown in phantom) are attached to the spray gun. Tip guard  120  includes a pair of forwardly extending wings which prevent the spray tip from inadvertently coming too close to a body part and possibly resulting in accidental injection of the body part with the stream of high pressure paint initially exiting the spray tip. A swivel coupling, designated  140 , is attached to the end of handle portion  116  to which is connected a high pressure hose (not shown) which delivers the paint under high pressure to the spray gun.  FIG. 2  shows a cross-sectional view of the prior art airless spray gun  110  of  FIG. 1  wherein an elongated filter  138  is housed in passageway  124  of handle portion  116 . Passageway  124  intersects passageway  122  which extends through barrel portion  114  and which houses needle assembly  128  actuated by trigger  136 . Activation by trigger  136  withdraws needle assembly  128  in passageway  122  to cause high pressure paint to flow from the high pressure hose connected to swivel coupling  140  through elongated filter  138 , passageway  122  and diffuser  134  and impinge upon spray tip  118  to be atomized suitable for spray painting. As clearly seen in  FIGS. 1 and 2 , handle portion  116  of spray gun housing  112  is a separate element from barrel portion  114  and is advantageously threadedly connected thereto resulting in a joint or seam  141  between the handle and barrel portions. The handle portion  116  of such a prior art airless spray gun is typically formed from extruded aluminum tubing which has its exterior machined by the spray gun manufacturer to form the spray gun handle. As can be appreciated, joint  141  is located in close proximity to the normal positioning of the user&#39;s hand during operation so that in the event any leak develops at the joint, there is the danger of injection of the user&#39;s hand by the high pressure paint. 
         [0015]      FIG. 3  is an exploded view of another prior art airless paint spray gun, designated  210 , wherein the housing includes a barrel portion  214  and a handle portion  216 . Barrel portion  214  houses a needle assembly  228 , spring  230 , end cap  226  and diffuser  234 . A spray tip and tip guard (not shown) are attached to the distal end of barrel portion  214  in front of diffuser  234 . Handle portion  216  houses a pipe like handle element  235  which is threadedly engaged with barrel portion  214  resulting in a joint or seam similar to joint  141  of spray gun  110 . Handle element  235  has inserted therein elongated filter  238 . Swivel coupling  240  is threadedly secured to handle element  235  and delivers high pressure paint thereto from a high pressure hose (not shown). Handle portion  216  may be aligned on the gun and secured to handle element  235  by means of a set screw (not shown). Typically, handle element  235  is formed from extruded aluminum tubing as is the case with handle portion  116  of prior art airless spray gun  110  of  FIGS. 1 and 2 . As in spray gun  110 , the extruded aluminum tubing is machined by the spray gun manufacturer to create the final form of handle element  235 . 
         [0016]    Now turning to the present invention, there is shown in  FIG. 4  an airless paint spray gun, generally designated  10 , including a housing  12  having a barrel portion  14  and a handle portion  16  depending from the barrel portion. At the distal end of barrel portion  14  a spray tip or nozzle  18  including a tip guard  20  are attached to the spray gun. A longitudinally oriented passageway, designated  22 , is arranged in barrel portion  14  which is intersected by passageway  24  extending through handle portion  16 . Passageway  22  extends throughout the length of barrel portion  14  and is capped at the rear end thereof by threaded end cap or nut  26  and terminates at the distal end thereof at spray tip  18 . A control needle assembly, designated  28 , is disposed in passageway  22  for controlling the spray of paint issuing from spray tip  18 . The needle of needle assembly  28  is biased by spring  30  to seat on and obstruct the bore  32  of diffuser  34  thereby preventing high pressure paint reaching spray tip  18  until the needle assembly is withdrawn by trigger  36 . An elongated filter, designated  38 , is disposed in passageway  24  for the purpose of filtering the paint which passes through passageway  24  on its way to passageway  22  and spray tip  18 . Paint is supplied to spray gun  10  via a high pressure hose (not shown) connected to swivel coupling  40  at the base of handle portion  16  which in turn communicates with passageway  24  in the handle portion. A spring, designated  42 , disposed between swivel coupling  40  and filter  38  biases filter  38  so that shoulder  44  thereof engages step  46  in passageway  24 . In this way all the paint introduced to passageway  24  must pass through filter  38 . 
         [0017]      FIG. 5  is a cross-sectional view of the spray gun housing  12  of  FIG. 1  and clearly shows that handle  16  is integrally formed with barrel  14  resulting in a one piece housing. Such a one piece construction is possible by using through-the-tool coolant drilling technology to produce passageway  24 . Through-the-tool coolant drilling causes drilling chips to be removed from the work by means of high pressure coolant passing through the center of the drill and forcing the chips along the flutes of the drill and out of the drilled hole. Through-the-tool coolant drilling is utilized where the length of the drilled hole is long compared to its diameter, as is the case of passageway  24 . Through-the-tool coolant drilling permits removal of potentially damaging chips and heat as the drill feeds deeper into the hole thus allowing high speed drilling and deeper holes. Passageway  24  comprises four stepped bores. The first, designated  48  accommodates swivel coupling  40 , the second and longest, designated  50 , accommodates elongated filter  38 , the third, designated  52 , accommodates the necked-in top end  54  of filter  38 , and the fourth, designated  56 , intersects with passageway  22  in barrel  14 . Step  46  is defined by the different diameters of bores  50  and  52 . 
         [0018]    Passageway  22  in barrel portion  14  comprises a series of stepped relatively short bores commencing with bore  58  at the rear of barrel portion  14  for accommodating end cap  26  and spring  30 , bores  60 ,  62  and  64  accommodate needle assembly  28 , and bore  66  accommodates diffuser  34 . 
         [0019]      FIG. 6  is an exploded view of spray gun  10  showing the various internal elements of the spray gun arranged in relationship to the spray gun housing  12 . As clearly seen, pivot pin  68  and nut  70  serve to secure trigger  36  to housing  12 . Pins  72  are housed in chambers (not shown) in housing  12  to be acted on by trigger  36  to retract needle assembly  28  against the biasing action of spring  30  to uncover bore  32  in diffuser  34  and permit the high pressure paint to impinge on spray tip  18  and be sprayed therefrom. Seal  74  seats against the head of diffuser  34  and seat  76  in bore  66  to seal the outer rim of diffuser  34  against leakage. As clearly seen in  FIG. 6 , elongated filter  38  is inserted into passageway  24  of handle portion  16  from the open bottom thereof and shoulder  44  of filter  38  is biased against step  46  in passageway  24  by spring  42  which is disposed between filter  38  and swivel coupling  40 . 
         [0020]    As a result of forming housing  12  in one piece, the resulting spray gun  10  is formed of fewer parts and is therefor simpler and easier to manufacture as well as being safer because of the elimination of the seam or joint between the handle and barrel portions of the spray gun. 
         [0021]    While only a single embodiment of the present invention has been shown and described, it will be obvious that many changes and modifications may be made thereto without departing from the spirit and scope of the present invention.