Abstract:
The paint spray gun includes an upper passageway for receiving gravity fed paint from an upper paint cup and a lower passageway for receiving suction fed paint from a lower paint cup or pressure fed paint from a remote pressurized paint tank via a hose. Plugs are provided to block the upper or lower passageway when the corresponding other passageway is being used.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a spray gun for paint and similar media which can be pressure fed, suction fed or gravity fed. 
     2. Description of the Prior Art 
     Spray guns for paint and similar media typically have a gravity feed, a suction feed or a pressure feed paint delivery system. 
     Gravity feed spray guns typically use a paint container on top of the spray gun, and the paint is fed by its own weight and atmospheric pressure, by gravity, into the spray gun. Gravity feed allows spraying of heavy materials, uses all of the material in the cup and is gaining wide popularity in automotive refinishing. Further, gravity feed requires less air pressure for operation than the suction or “siphon” feed method. The use of liners allows for simple cleaning of the device after use and provides for upside-down spraying. Gravity feed spray guns are disclosed in U.S. Pat. No. 5,727,736 entitled “Spray Applicator with Air Shut-Off Valve” issued on Mar. 17, 1998 to Tryon and U.S. Pat. No. 4,811,904 entitled “Spray Medium Inset for Spraying Pistols and a Spraying Pistol Suitable for Application of Such Insets” issued on Mar. 14, 1989 to Ihmels et al. 
     Suction feed spray guns use a suction created by a pressurized air source to draw the paint from a container up into the pressurized air stream. Suction feed typically allows larger quantities of paint to be used compared to gravity feed systems. Additionally, different paints or colors can be stored in different suction feed cups ready for use. Suction feed paint sprayers have achieved wide popularity among many end user segments. A suction feed spray gun is disclosed in U.S. Pat. No. 5,655,714 entitled “Pivotable Syphon Tube” and issued on Aug. 12, 1997 to Kieffer et al. 
     Pressure feed spray guns use a pressurized air line to the paint container to pressurize the paint and force it into the spray gun. Pressure feed allows spraying of extremely heavy materials, particularly when a large paint capacity is required, such as more than one quart. Pressure feed allows the spray gun to be held upside-down while spraying without the concern of leaks or drips. Moreover, a pressure feed spray gun is light because the paint supply can be separate from the spray gun. 
     Therefore, different paint applications and different users may choose different spray guns—gravity feed, suction feed or pressure feed. However, a single user may be reluctant to acquire spray guns of all three types. U.S. Pat. No. 4,760,962 entitled “Spray Gun Paint Cup and Lid Assembly” issued on Aug. 2, 1988 to Wheeler provides for the selection of pressure feed or suction feed but does not provide for gravity feed. Additionally, the configurations required for the two different feeds may not be intuitively obvious to a user. Similarly, U.S. Pat. No. 4,174,071 entitled “Spray Gun Assembly” issued on Nov. 13, 1979 to Lau et al. discloses a spray gun with an optionally pressurized paint supply. U.S. Pat. No. 5,069,389 entitled “Adapter for an Air Spray Gun” issued on Dec. 3, 1991 to Bitsakos provides a gravity feed attachment to a conventional spray gun. U.S. Pat. No. 5,582,350 entitled “Hand Held Paint Spray Gun with Top Mounted Paint Cup”, issued on Dec. 10, 1996 to Kosmyna et al. discloses a hand held paint spray gun with a top mounted paint cup. The spray gun can operate as both a gravity and a suction feed. 
     OBJECTS AND SUMMARY OF THE INVENTION 
     It is therefore an object of this invention to provide a spray gun which can be configured as a gravity feed spray gun with all of the advantages thereof. 
     It is therefore a further object of this invention to provide a spray gun which can be configured as a pressure feed spray gun with all of the advantages thereof. 
     It is therefore a still further object of this invention to provide a spray gun which can be configured as a suction feed spray gun with all of the advantages thereof. 
     It is therefore a still further object of this invention to provide a spray gun in which the respective gravity, pressure and suction feed mode configurations are intuitively obvious to the user. 
     These and other objects are attained by providing a paint spray gun with an upper feed passageway and a lower feed passageway. The upper feed passageway is used during the gravity feed mode and is blocked during the suction and pressure feed modes. The lower feed passageway is used during the suction and pressure feed modes and is blocked during the gravity feed mode. A fluid hose leading from a remote pressurized paint tank is used during the pressure feed mode to feed paint through the lower feed passageway. A paint cup leading to the lower feed passageway is used during the suction feed mode. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Further objects and advantages of the invention will become apparent from the following description and claims, and from the accompanying drawings, wherein: 
     FIG. 1 is a cross-sectional view, partially in phantom, of the spray gun of the present invention. 
     FIG. 2 is a perspective view of the spray gun of the present invention, including the various attachments to effect the various feed configurations. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings in detail wherein like numerals refer to like elements throughout the several views, one sees that FIG. 1 is a cross-sectional view, partially in phantom, of the spray gun  10  of the present invention. Spray gun  10  includes pistol grip  12  through which air passageway  14  extends. Lower end  16  of pistol grip  12  receives compressed air hose  100  through aperture  18 . 
     Air passageway  14  leads to air needle valve passageway  30  which leads horizontally through body  31  of spray gun  10 . Air needle valve passageway  30  contains air needle valve  32  which is controlled by air needle valve knob  34  to control the flow of pressurized air therethrough to nozzle  36 . 
     Trigger  38  is pivotably attached to body  31  of spray gun  10  on pivot point  40 . Trigger  38  is affixed to paint needle valve  42  which travels with forward paint needle valve channel  44  and rear paint needle valve channel  46 . Rear paint needle valve channel  46  is rearwardly bounded by paint needle valve knob  48 . Forward paint needle valve channel  44  is bounded by nozzle  36  which is controlled by the relative insertion or retraction of paint needle valve  42  therein. Enlarged paint chamber  50  is formed within forward paint needle valve channel  44 . Enlarged paint chamber  50  is in fluid communication with upper feed passageway  52  and lower feed passageway  54 . Upper feed chamber  52  extends to upper aperture  56  in the upper surface of body  31 . In the suction feed and pressure feed modes, upper aperture  56  is blocked by removable plug  60  and washer  58 . Removable plug  60  is typically shaped as a gun hook assembly. However, in the gravity feed mode, upper aperture  56  communicates with feed  62  of gravity feed cup  64 . In this gravity feed mode, paint is fed from gravity feed cup  64 , through upper feed passageway  52  to enlarged paint chamber  50 . From enlarged paint chamber  50 , paint is drawn to nozzle  36  and out nozzle  36  by the compressed air passing through air needle valve passageway  30 . Preferably, upper feed passageway  52  does not intersect air needle valve passageway  30 . 
     Lower feed passageway  54  extends downwardly from enlarged paint chamber  50  and axially through threaded stem  66  to lower aperture  68 . In the pressure feed and suction feed configurations, feed tube  70  extends downwardly from lower aperture  68  and paint cup  26  is threadably attached to threaded stem  66 . In the pressure feed mode, hose  22  is attached to threaded stem  66  and receives paint from a remote pressure-fed paint tank (not shown). The paint is thereby forced up lower feed passageway  54  to enlarged paint chamber  50  and out nozzle  36 . In the suction feed mode, paint cup  26  is attached to threaded stem  66 . The passage of pressurized air through air needle valve passageway  30  and nozzle  36  creates a suction which draws paint up through feed tube  70  and lower feed passageway  54  to enlarged paint chamber  50  and nozzle  36 . In the gravity feed mode, paint cup  26  is omitted and lower aperture  68  is blocked by threaded plug  72 . 
     FIG. 2 shows a typical packaging configuration for consumer purposes, including spray gun  10 , paint cup  26 , hose  22 , gravity feed cup  64 , feed tube  70 , threaded plug  72 , along with repair kit  80 , instructions  82 , roll of liners  84  (for gravity feed cup  64 ), bushings  85 , bushing tool  86 , and cleaning brushes  88 , all contained within package  200 . 
     To use spray gun  10 , the user decides which configuration is desired and attaches the devices as described hereinabove. That is, in the pressure feed mode, hose  22  is attached to threaded stem  66  and a remote pressurized paint tank (not shown). Additionally, washer  58  and removable plug  60  are inserted into upper aperture  56 . In the suction feed mode, paint cup  26  is attached to threaded stem  66  and hose  22  is omitted. Washer  58  and removable plug  60  are similarly installed. In the gravity feed mode, hose  22 , paint cup  26 , washer  58  and removable plug  60  are omitted and threaded plug  72  and gravity feed cup  64  are installed. 
     Thus the several aforementioned objects and advantages are most effectively attained. Although a single preferred embodiment of the invention has been disclosed and described in detail herein, it should be understood that this invention is in no sense limited thereby and its scope is to be determined by that of the appended claims.