Abstract:
A hand-operated pump dispenser for dosing liquid product from a container includes a rotatable plunger assembly which is manually lifted upwardly relative to the dispenser body for drawing product into a pump chamber in a preselected amount depending on the rotational setting of the plunger, and which is manually depressed for completely discharging the contents of the chamber.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates generally to a manually actuated dispenser for the metered dosing of fluid from a container to which the dispenser is attached. More particularly, the dispenser has a variable volume pump chamber which is charged upon manually lifting or extending a plunger and is discharged upon manual plunger depression. The charging stroke is limited and may be selective. 
     The invention is an improvement over U.S. Pat. No. 5,967,377 disclosing a metered dispenser having a variable volume pump chamber which is charged to a measured volume as indicated by a marking on the plunger, and which is discharged by inverting the metered dispenser. The charged volume of the chamber cannot, however, be controlled with any precision since the metering element which defines a pump cylinder is lifted to draw a selected amount of fluid into the chamber as determined by markings on the metered element which indicate predetermined liquid volumes therein. Moreover, the metered dispenser has limited use in that it must be inverted to permit fluid to drain from the metering element by gravity or to be expelled by squeezing the liquid dispenser and/or the metering element. However, if the liquid is viscous, the contents of the pump chamber may not be fully discharged by gravity or even by squeezing the dispenser or the metering element. Besides, the vertically slidable metering element could shift easily in the process of being inverted during discharge whereby additional liquid would fill the metering element inadvertently, thereby affecting the accuracy of the doser. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to provide a metered dispenser which avoids the drawbacks of the known prior art dosers and which is capable of accurately metering liquid product in an upright position. 
     Another object is to provide a metered dispenser having at least one limit stop for limiting the extractable plunger for suctioning a predetermined volume of product into the pump chamber such that upon full depression of the plunger assembly, an accurate amount of product is dosed through a valve control discharge passage which may be in the form of a spout. 
     The plunger of the dispenser according to the invention is rotatable amount is central axis and has at least one radial projection which bears against a limit stop when lifted to extract liquid from the container to which the dispenser is mounted. The dispenser may have a plurality of limit stops in stepped formation respectively associated with indicia marked in accordance with the predetermined setting. A lock shoulder cooperating with the radial projection may be provided for locking the plunger in its fully depressed position. 
     Other objects, advantages, and novel features of the invention will become more apparent from the following detailed description of the invention when taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of the metered dispenser of the invention shown in its fully depressed position; 
     FIG. 2 is a view similar to FIG. 1 showing the plunger in its outwardly extended or lifted position; 
     FIG. 3 is a vertical sectional view of the metered dispenser of the invention shown mounted on the neck of the container of product to be dispensed, and 
     FIG. 4 is a sectional view taken substantially along the line  4 — 4  of FIG.  3 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Turning now to the drawings wherein like reference characters refer to like and corresponding parts throughout the several views, the metered dispenser according to the invention is generally designated  10  in FIGS. 1 to  3  and is shown in detail in FIG. 3 in the fully extended position of the plunger. The dispenser  10  includes a dispenser body having a closure  11  for mounting the dispenser to a container  12  of product to be dispensed. The closure suspends a conventional dip tube  13  which extends into the container and defines together with a hollow upstanding pump piston  14  an inlet passage  15  valved as by an inlet check valve  16 . The piston has a valve seal  17  at its upper end in sliding sealing engagement with cylindrical skirt  18  of plunger assembly  19 , the skirt essentially defining a pump cylinder which reciprocates manually relative to the stationary piston. Valve seal  17  may comprise a separate part secured to piston  14  in some manner, or may be integral with the piston. 
     The piston and cylinder together define a variable volume pump chamber  21  for containing a metered amount of liquid product drawn from the container. The plunger assembly further includes a plunger head  22  having formed therein a discharge passage  23  valved as by a one-way check valve  20  and terminating in a discharge spout  24 . 
     The closure has an upstanding sleeve  25  containing a cylindrical liner  26  fixed within sleeve  25  in some normal manner. The liner has at its upper end an inner annular flange  27  or the like for arresting upward movement of the plunger assembly to its fully extended position of FIGS. 2 and 3 as a pair of opposing radially extending projections  28  on skirt  18  bear against flange  27  as shown in FIG.  3 . Of course, only one of such projections  28  need be provided, and the liner may be removably mounted within sleeve  25  so as to be replaceable by a different set of stops, or may be integral with sleeve  25 . 
     Plunger assembly  19  is rotatable about the central axis of cylindrical skirt  18  and is manually reciprocable between the upwardly extended position of FIGS. 2,  3  and the fully depressed position of FIG.  1 . Liner  26  has at its lowermost end a projection  29  extending radially inwardly and spaced a predetermined distance from top wall  31  of the closure. Thus, in the fully depressed position of the plunger assembly with the skirt  18  shown in phantom outline in FIG. 3, one of the projections  28  can be rotated to underlie projection  29  for locking the plunger assembly in its fully retracted position of FIG.  1 . 
     Top wall  31  of closure  11  is provided with a vent port  30  through which atmospheric air passes into the container during each upward reciprocation of the plunger so that product drawn from the container is displaced with air to avoid container collapse. The inner diameter of annular flange  27  is slightly less than the outer diameter of skirt  18  so as to define a slight annular gap therebetween forming a passage for the entry of air into the container together with vent port  30  in any uplifted position of the plunger from that shown in phantom outline in FIG.  3 . In the plunger lock-down position shown in phantom outline in FIG. 3, projection  28  bear against the upper surface of top wall  31 . 
     The vent port  30  is located in wall  31  at such a location as to be covered by one of the projections  28  in the plunger lock-down position shown in phantom in FIGS. 3 and 4. Also the vent port is shown located at a  180 ° spacing from projection  29  such that in the plunger lock-down position the vent port is sealed closed by one of the projections  28  which is located opposite that projection  28  which underlies projection  29 . Otherwise vent port  30  can be located as to be covered by that projection  28  which underlies projection  29 . 
     The liner is further provided with one or more additional limit stops presenting stop shoulders  32 ,  33 ,  34  and  35  in stepped form each presenting a gradually higher stop for limiting the outward extent of the plunger assembly upon rotation of the plunger placing a projection in alignment with a selected one of the stop shoulders. 
     Indicia in the form a triangular or the like marker  36  may be provided on the plunger head near the lower edge thereof, and spaced indicia such as the numbers “0”, “1”, “2”, etc., with vertical markers such as  37  can be provided on sleeve  25 , with the spacing of markers  37  coinciding with the effective width of each of the respective stop shoulders  32  to  35 . 
     Thus, in operation, the metered dispenser would be shipped mounted on container  12  filled with product to be dispensed and shelved in its fully retracted and locked position of FIG.  1 . In such position marker  37  is at the “0” setting indicating a locked position. When plunger assembly  19  is rotated in the direction of curved arrow  38  of FIG. 1, the plunger assembly is unlocked and is now capable of being lifted by the operator to any of its settings  1 ,  2 ,  3 ,  4 , etc., depending on the extent of plunger assembly rotation. Assuming the plunger assembly is rotated such that marker  36  coincides with marker  37  at the  2  position, one of projections  28  on sleeve  18  will have been rotated into alignment with stop shoulder  33  such that on pulling the plunger assembly in the direction of arrow  39 , its outward extent is limited by bearing engagement between established projection  28  and stop shoulder  33 . Therefore only a predetermined amount of liquid is drawn into chamber  21  by the suction created upon expansion of chamber during upward movement of sleeve  18  which draws product up through inlet passage  15  from the container and into the pump chamber via open ball check valve  16 . The metered amount of liquid in chamber  16  may then be discharged from the chamber upon simply manually applying a downwardly depressing force to the plunger head in the direction of arrow  41  shown in FIG. 2 with the plunger shown in phantom outline. When the plunger is depressed to its fully compressed position of FIG.  1  and shown in phantom outline in FIG. 2, the entirety of the measured product is discharged from pump chamber  21 . Then while the plunger assembly is in its fully depressed position, it may be rotated clockwise back to its “ 0 ” position, whereupon it is again locked in the FIG. 1 position and cannot leak through either check valve  16  or  20  in the locked position even when tipped over since the plunger chamber has been completely evacuated. 
     On the next use opportunity by the operator, the plunger head is rotated counterclockwise in the direction of arrow  38  until its marker  37  coincides with a selected setting whereupon the plunger head is pulled upwardly in the direction of arrow  39  such that projection  28  again underlies one of the stop shoulders  32  to  35  to which it is placed in alignment for withdrawing a preselected volume of liquid product from the container up through inlet passage  15  and into the pump chamber whereafter upon manual depression of the plunger head to its position in phantom outline in the direction of arrow  41  of FIG. 2, the entirety of pump chamber  21  is discharged through discharge spout  24  to its intended target. And, while in the fully depressed position, the plunger assembly simply need be rotated again in a clockwise direction until its marker  36  reaches the “0” position at which position the plunger assembly is locked in place in its FIG. 1 position. 
     In the plunger lock-down position the container is sealed against leakage through the vent port which is sealed tightly closed by one of projections  28  which overlies the vent port in the tightly locked position. When the plunger is rotated counterclockwise to unlock it, the vent port is opened and air is drawn into the container as the plunger is uplifted which expands chamber  21  creating a sub-atmospheric condition permitting product to be drawn at its atmospheric level within the container up through passage  15  and into the chamber. This product is displaced with air through the vent passage formed by the annular space between skirt  18  and flange  27  and by vent port  30 . Since after each use the dispenser head is depressed and locked in its down position, the dispenser package is sealed against leakage even when dropped, tilted on its side, or inverted. 
     Obviously, many modifications and variations of the present invention are made possible within the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.