Abstract:
A structurally improved spray gun includes a hollow housing having a hollow handle, an electromagnet in the housing to acturate an oscillating armature which repeatedly impinges a piston in a cylinder to aspirate the paint from a container into the cylinder to spray out to the atmosphere through a nozzle at front of the cylinder. It is characterized in a locking device which is disposed in the housing beneath the cylinder to lock or unlock the cylinder in a rapid and convenient manner.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention relates to spray guns and more particularly to a locking device for spray gun which device facilitates a rapid positioning and readily disassembling of a cylinder inside the spray gun.  
           [0002]    Typical spray gun  1  (as shown in FIG. 1) comprises a container  2 , a lid  3 , a cylinder  4  and a electromagnet  5  inside the housing to actuate an oscillating armature  6  to force a piston  8  moving forward so as to aspirate the paint inside the container  2  into the cylinder  4  spraying out to the atmosphere through a nozzle  11 . An adjustable anvil  7  on the right side of the oscillating armature  6  to adjust the oscillating extent of the armature  6 . The electromagnet  5  is controlled by a press button  10 . Because of the lid  3  is integrated with the cylinder  4 , the lid  3  must be secured to the bottom  12  of the housing by screws  9  prior to the assembly of the cylinder  4  into the housing. It is known that after finish of a job, a certain amount of paint may congeal in the cylinder  4 . To clean there congealed paint, the cylinder  4  must be disassembled by unfastening a plurality of screws  9 . This is wearisome job and waste time.  
           [0003]    U.S. Pat. No. 3,680,789 and U.S. Pat. No. 3,899,134 all adopt fastening means that difficult to assemble or disassemble. And U.S. Pat. No. 2,999,646 and U.S. Pat. No. 3,445,068 also have the disadvantage of integration of the lid with the housing. It causes more difficult to remove the cylinder out of the spray gun to clean up.  
           [0004]    Recently, some of the producers adapt threaded cylinder. But it is still inconvenient.  
         SUMMARY OF THE PRESENT INVENTION  
         [0005]    The present invention has a main object to provide a structurally improved spray gun in which a locking device is provided to facilitate a rapid assembling and/or disassembling the cylinder into the housing of the spray gun and the assembly is rather stable.  
           [0006]    Accordingly, the structurally improved spray gun of the present invention comprises a hollow housing with a handle, an electromagnet in the housing operated by a pressbutton switch, an oscillating armature pivoted to a rear side of the electromagnet which actuates the armature to make oscillatory action, an adjustable anvil to control the oscillatory span of the armature, a cylinder disposed in side the housing in which is an elastic no-return cork in frontend and an elastic piston in rear end, a nozzle at front end of the cylinder and a lid integrated with the bottom of the cylinder to engage with a container containing the paint. When the armature impinges the piston to move forward, the paint is aspirated from the container into the cylinder and sprayed out to the atmosphere through the nozzle. This disclosure is characterized in that a locking device is provided in the housing make incorporation with the check blocks on the outer periphery of the cylinder so as to facilitate a rapid assembly and/or disassembly of the cylinder into the housing and the assembly is rather stable.  
           [0007]    The present invention will become more fully understood by reference to the following detailed description thereof when read in conjunction with the attached drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]    [0008]FIG. 1 is a vertical side view to show a spray gun according to a prior art,  
         [0009]    [0009]FIG. 2 is a vertical side view and partially sectional view to show a spray gun of the preferred embodiment according to the present invention,  
         [0010]    [0010]FIG. 3 is an exploded perspective view to show a cylinder and a locking device,  
         [0011]    [0011]FIG. 4 is a top plane view to show the relationship between cylinder and the housing,  
         [0012]    [0012]FIG. 5 is a vertical side view to show the assembly of the spray gun of the present invention,  
         [0013]    [0013]FIG. 6 is a front view of the spray gun of the present invention,  
         [0014]    [0014]FIG. 7 is a top view to show the assembly of the cylinder with the housing and the locking device,  
         [0015]    [0015]FIG. 8 is a front view and partially sectional view to show the locking device locked the cylinder,  
         [0016]    [0016]FIG. 9 is a front view and partially sectional view to the locking device unlocked the cylinder,  
         [0017]    [0017]FIG. 10 is an exploded perspective view to show an alternate locking device and an alternate cylinder, and  
         [0018]    [0018]FIG. 11 is a front view and partially sectional view to shown the alternate locking device at a locked position. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0019]    With reference to FIGS.  2  to  5  of the drawings, the spray gun of the present invention comprises a hollow housing  20  having a hollow handle  20 A, an electromagnet  21  in the housing  20  operated by a press button switch  24  in the handle, an oscillating armature  22  pivoted to a rear side of the electromagnet  21  and actuated by the electromagnet  21  to perform oscillatory actions, an adjustable anvil  23  which is operated by a swing button to move forward or backward to control the oscillatory span of the armature  22 , a cylinder  30  integrated with a internally threaded lid  31  disposed into the housing  20  having in rear end a piston  32  biased by a coil spring  33  and in front end a no-return cork  34  biased by a spring  35 , a nozzle  36  screw fastened to the front end thereof, a return pipe  37  and a out pipe  38  spacedly formed under the cylinder  30  and communicated with the cylinder  30  and a container  40  which is screw fastened to the lid  31  for containing the paint. The housing  20  further has an opening  50  in front end integrated with a receiving groove  251  and a rectangular groove  252  (as shown in FIG. 6) and a positioning guide  26 .  
         [0020]    It is characterized that a locking device  50  is adapted to lock the cylinder  30  inside the housing  20 . The locking device  50  is of a inverse U-shaped section and has a positioning aperture  51  in a lateral portion  54  to receive a spring  52  which has other end disposed on a post  27  on an inner wall of the housing  20  and a button  53  on the other side opposite to the aperture  51  disposed in a thru hole  28  (as shown in FIGS. 7, 8 and  9 ). The locking device  50  is elastic because of the spring  52  and stable because of the positioning guide  26 . On a lateral periphery of the cylinder  30 , there is a first stop block  301  and a second stop block  302  engageable into the rectangular groove  252  and defined a gap  304  therebetween receivable with the lateral portion  54  of the inverse U-shaped locking device  50 , the second stop block  302  has a beveled surface  303  in order that the second stop block  303  can readily pass over the lateral portion  54  which is than engaged into the gap  304  because of the resilience of the spring  52 . Therefore the cylinder  30  is firmly locked up without moving transversely. To prevent an inadvertent touching, the button  53  of the locking device  50  is embedded into the thru hole  28  of the housing  20 . When presses the button  53  inward, the lateral portion  54  moves laterally to disengaged with the gap  304 . So that the cylinder  30  together with the lid  31  enables to draw out of the housing  20 . The locking or unlocking of the cylinder  30  is rather rapid without any tool.  
         [0021]    In operation, the oscillating armature  22  actuated by the electromagnet  21  performs continuous oscillation to impinge against the piston  32  to move forward and the resilience of the coil spring  33  immediately forces the piston  32  to move backward so that the repeated sliding movement aspirates the paint into the cylinder  30  and the sprays out to the atmosphere through nozzle  36 .  
         [0022]    Referring to FIGS. 10 and 11 of the drawings, an alternate embodiment of a locking device  60  is provided, the locking device  60  has a vertical rectangular bar  64 , an aperture  61  in the top of the bar  64  for engaging on end of a spring  62  which has the other end secured on a post  205  centrally formed on the inner surface of an upper wall of the housing  20  and a sliding button  63  perpendicularly connected to the bar  64  through a transverse rod. To coordinate with, a first stop block  301 ′ and a second stop block  302 ′ now is formed on the top periphery of the cylinder  30  to replace with the stop blocks  301  and  302 , a gap  304 ′ is also defined between the blocks  301 ′ and  302 ′ to replace with the gap  304  and is engageable with the bar  64  of the locking device  60 . Further, the second slop block  302  has also a beveled surface  303 ′ and in the housing  20 , a rectangular groove  252  is moved to the top of the receiving groove  251  and re-designated as  202 , the thru hole  28  is now becoming an oblong hole  204  and the positioning guide  26  is now moved to the center of the housing  20  and re-designated a  26 A.  
         [0023]    When assembling, slide the cylinder  30  into the housing  20  through the receiving groove  201  and the rectangular groove  202 , the second stop block  302 ′ will be smoothly passed the rectangular bar  64  of the locking device  60  because of the beveled surface  303 ′ so that the rectangular bar  64  will be automatically engaged into the gap  304 ′ for the resilience of the spring  62 . Therefore, the cylinder  30  is firmly locked up. When slides the sliding button  63  upward to have the rectangular bar moving up to disengage with the gap  304 ′, the cylinder  30  is readily drawn out of the housing  20 .  
         [0024]    The specification relating to the above embodiment should be construed as exemplary rather than as limitative of the present invention, with many variations and modifications being readily attainable by a person of average skill in the art without departing from the spirit or scope thereof as defined by the appended claims and their legal equivalents.