Patent Publication Number: US-4840294-A

Title: Adjustable dispensing tool

Description:
BACKGROUND AND SUMMARY OF THE INVENTION 
     The present invention relates to a tool for dispensing fluids such as two-part epoxy components. The tool employs a lever mechanism, the mechanical advantage of which can be adjusted to accommodate fluids having different viscosities. 
     The need for the ability to dispense materials of different viscosities arises in at least two situations. First, the same material may change viscosity significantly as a result of changes in temperature. Secondly, a user may want to use a single tool to dispense different materials having significantly different formulations, and therefore, viscosities, because application may require that such formulations be used. 
     The tool of the present invention includes a frame which is preferably able to hold a cartridge having two separate chambers. A pair of pistons and corresponding parallel piston rods are carried by the frame. A third pushing rod, parallel to the piston rods, is attached to the piston rods at one end. Axial forces applied to the pushing rod are transferred to the piston rods through a connecting plate. A canted nut has an aperture through which the pushing rod extends. A lever actuates the canted nut causing axial movement of the rods. 
     The lever of the tool is comprised of an externally threaded bolt or trigger, which threads into an internally threaded fulcrum adjacent to the canted nut. One end of the bolt contacts the canted nut as the bolt moves in a pivoting motion about the pivot axis of the fulcrum. Rotation of the bolt varies the distance between the pivot axis and the point of contact between the bolt and the canted nut. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a tool embodying the present invention; 
     FIG. 2 is a sectional view taken along line 2--2 of FIG. 3; 
     FIG. 3 is a longitudinal view in partial section of the tool shown in FIGS. 1 and 2. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION 
     In FIG. 1, an overall view of the tool 10, shows a cartridge carrying frame 11 having a yoke 12 at one end and base plate 13 at the other. Projecting through the base plate 13 are three rods, two piston rods 14 and 15, and a pushing rod 16. The three rods are joined at one end by a connecting plate 17. Pistons 18 and 19 are fixed to the ends of the piston rods 14 and 15, respectively. 
     A rod actuating housing 20 is mounted to the base plate 13. A rear handle 21 and trigger 22 depends from one side of the housing 20. 
     FIGS. 2 and 3 shown the internal components of the housing 20 and the trigger 22. A canted nut or feed plate 23 surrounds the pushing rod 16. Eccentric forces are applied to the feed plate 23 by a lever bolt 24 having a rounded end 25. The bolt 24 has threads 26 over a portion of its length. The threads 26 of the bolt 24 mate with the threads 27 of a nut which acts as a fulcrum 28. The fulcrum 28 is supported by pins 29 and 30 attached to the housing 20. The pins 29 and 30 define a pivot axis 31, perpendicular to the bolt 24, about which the bolt 24 and fulcrum 28 pivot. 
     The bolt 24 has an enlarged knurled end 32 to facilitate rotation of the bolt 24 within the fulcrum 28. Such rotation causes axial movement of the bolt 24, resulting in a change in the distance between the point at which the rounded end 25 contacts the feed plate 23 and the pivot axis 31. The axial position of the bolt 24 can be fixed by use of the locking sleeve 33. The sleeve 33 is threaded on to the bolt 24 and can be tightened against the fulcrum, which is prevented from rotating about the bolt 24. Axial adjustment of the bolt 24 is facilitated by the presence of a curved surface 35 on the feed plate 23, which is oriented generally parallel to the trigger 22 when at rest. The bolt 24 has an unthreaded cylindrical section 34 adjacent to the rounded end 25. The curvature of the cylindical section 34, the rounded end 25, and the curved surface 35 are all generally equal. 
     Changing the distance between the point at which the rounded end 25 contacts the feed plate 23 and the pivot axis 31 varies the mechanical advantage of the trigger. This means that without changing the operator&#39;s hand positions on the trigger 22 or rear handle 21, materials of different viscosities can be dispensed with the same amount of squeezing force. 
     While the invention has been described herein with reference to a certain embodiment, it should be understood that many variations, alternatives, and modifications may be made to the descibed embodiment without departing from the spirit and scope of the appended claims.