Abstract:
A device for accurately dispensing a volume of fluid that is predetermined by limiting the outward travel distance of a plunger within a fluid chamber. The plunger limit stop is attached to a scale post having raised indicia lines and is adjustable therealong by a detent engagement wherein the limit stop is selectively positioned to engage one of a plurality of notches formed on the scale post between its volume indicia raised lines.

Description:
BACKGROUND OF THE INVENTION 
     This invention is an improvement over the liquid dispensing device disclosed in U.S. Pat. No. 3,452,901, granted July 1, 1969. In this prior patent, which is expressly incorporated herein by reference, a liquid dispensing device is provided for mounting on liquid jars wherein a plunger is manually movable out of and into a liquid pump chamber from the top of the jar in order to discharge liquid therefrom. An adjustable stop is provided to limit plunger movement out of the pump chamber. A graduated liquid volume scale is provided to permit adjustment of the stop to a desired volume of liquid to be discharged in one full stroke of the plunger. 
     Although such a liquid dispensing device has been very satisfactory, it does require some operator judgment in aligning the stop with the desired volume as indicated on the scale since an infinite number of such positions are possible. Therefore, it is a primary object of this invention to provide an improved volume setting device which reduces the amount of operator judgment that is required for accurate volume settings. 
     SUMMARY OF THE INVENTION 
     This and additional objects are accomplished by the present invention wherein the indicia markings of the scale post are raised outward on the surface of a scale post in a manner forming notches therebetween. A volume indicator on the movable stop is shaped to be inserted into these notches. An operator thus has a finite number of positive positions with which to set the plunger stop, each setting being carefully calibrated. The result is improved accuracy of liquid discharge of those finite liquid volumes. Any of these volume settings may be selected with repeatability of results. 
     The improvement of the present invention has only been generally summarized. Additional objects, advantages and features thereof are included in the following description of its preferred embodiment, which description should be taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a cross-sectional view of a liquid dispenser according to U.S. Pat. No. 3,452,901 positioned on a bottle for use and including the improvement of the present invention; 
     FIG. 2 is an enlarged perspective view of the improved adjustment mechanism of the liquid dispenser of FIG. 1; 
     FIG. 3 is a sectional view of the improvement of FIG. 2 taken across line 3--3 thereof; 
     FIG. 4 is the same view as FIG. 3 with the parts thereof having a different relative position; and 
     FIG. 5 is a sectional view of FIG. 2 taken across section 5--5 thereof. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 shows the environment in which the present invention exists and is substantially the same as FIG. 1 of aforementioned U.S. Pat. No. 3,452,901 except that certain unnecessary detail has been omitted and the reference characters as applied to the improved items claimed herein are provided with a prime. Briefly, a glass bottle 1 or other container having a threaded top contains a cap structure 2 threaded thereon. A cylindrical barrel 12 forms a piston chamber in which a plunger 11 is slidably held with one end thereof existing in the cylinder and the other end thereof having an operating handle 17 attached thereto. When the plunger 11 is withdrawn from within the bottle 1, liquid is drawn in through the valve 25 to the barrel 12. As the plunger 11 is depressed into the bottle, liquid is forced out of the barrel 12 through the valve 26 and out of a liquid delivery tip 28. 
     An operator depresses the knob 17 as far as possible, until it abuts the top of the cap 2, when discharging liquid from the tip 28. Therefore, the volume of liquid dispensed depends upon how far the plunger 11 was withdrawn from the barrel 12 before such depression began. In order to control the beginning position of the knob 17 and thus the plunger 11, a scale post 5&#39; is attached to the cap 2 and extends upwardly adjacent the path taken by the knob 17 as the plunger 11 is moved into and out of the barrel 12. The post 5 is rigidly attached by a screw 6 to the cap 2. An indicator stop member 8 is held by the scale post 5&#39; and may be moved up and down by hand along a graduated volume scale 7&#39;. A screw 9 provides a means to rigidly attach the stop member 8&#39; to the scale post 5&#39;. A pointer 10&#39; marks on the scale 7&#39; the volume of liquid that will be discharged from the tip 28 upon full depression of the knob 17 from abuttment on the underside of the stop member 8&#39;. 
     The scale post of the previous dispenser design as illustrated in aforesaid U.S. Pat. No. 3,452,901 is substantially smooth with its stop member being substantially nonrotatable about the scale post. The improvement of the present invention, on the other hand, is constructed on plane surface 101 of an otherwise cylindrically shaped scale post 5&#39;. Indicia marks along the length of the plane surface 101, such as the marks 103 and 105, for example, are not merely printed on the surface 101 as herein before but rather are raised outward therefrom a sufficient distance to form notches therebetween, such as the notch 107. The pointer 10&#39; is shaped for reasonably tight engagement into each of these notches, as best illustrated in FIGS. 2 and 5. This structure thus permits an operator to select one of a finite number of volumes by inserting the indicator 10&#39; into an appropriate one of the notches along the height of the scale post 5&#39;. The co-operating shape between the notches, such as the notch 107, and the indicator 10&#39; securely holds the stop member 8&#39; at one of these finite locations against movement along the scale post 5&#39;. 
     The raised indicia lines, such as the lines 103 and 105, are parallel to one another extending from an edge of the plane surface 101. The portion of these indicia lines immediately adjacent the edge is thickened for strength since the indicator 10&#39; is forced thereagainst to some extent when being inserted into notches formed by these thickened portions. Numerical indications of volume are also provided on the surface 101 at some of the raised indicia lines, as shown best in FIG. 2. 
     The stop member 8&#39; is made to be rotatable with respect to the scale post 5&#39; in order to permit disengagement of the indicator 10&#39; from a notch and movement thereof to some other notch. The inside surface of the stop member 8&#39; is generally circular corresponding to the circular shape of the scale post 5&#39; in a plane perpendicular to its longitudinal axis. An exception, however, is a discontinuity 109 which is seen best in FIG. 3. This discontinuity positioned to engage an edge 111 of the scale post 5&#39; with the indicator 10&#39; at a position outside of the notches, as shown in FIG. 4, so that the stop member 8&#39; may be slid up and down the scale post 5&#39;. A thumb screw 9 is threadedly attached through an aperature of the stop member 8&#39; to provide a latching of the stop member 8&#39; against rotation, as shown in FIG. 3. 
     Besides the advantage of having a finite member of very precise volumes that are setable by the improvement of the present invention, an operator may, if desired, chose some other volume setting in between the positions provided. By rotating the stop member 8 to the position shown in FIG. 4 and in dotted outline in FIG. 2, any position may be assumed along the scale post 5&#39;. When the stop member 8 has been moved so that the indicator 10&#39; is at the desired indicia mark of the scale post 5&#39;, the screw 9 may be clamped against the post 5&#39; to hold the stop member 8&#39; in position. 
     It will be understood that although a specific embodiment of the present invention has been described, that the present invention will be accorded its full protection within the scope of the appended claims. Particularly, this improvement has applications in other fluid dispensing devices where improved accuracy and reduced human error in setting the volumes of fluid to be displaced are desired.