US3738545A - Sliding plunger dispensing closure - Google Patents

Abstract

To prevent large increases in the force required to pull a sliding plunger of a dispenser closure to its open position and to prevent cold flowing of an enlarged annular sealing surface on the plunger, the annular sealing surface is located within the confines of a smaller diameter aperture when the plunger is in its closed position and blocking fluid flow. Preferably, the plunger is positively retained against popping up to the open position by a sealing ring which is deflected radially outwardly with insertion of the annular sealing surface therein and which, when deflected, exerts a gripping force on the annular sealing surface of the plunger.

Description

United StatesPatent 1191 Roy June 12, 1973 SLIDING PLUNGER DISPENSING CLOSURE [75] Inventor: Gerald L. Roy, Lancaster, Pa.

[73] Assignee: Kerr Glass Manufacturing Corporation, Los Angeles, Calif.

22 Filed: Mar. 12, 1971 211 App]. No.: 123,610

[52] [1.8. Cl. 222/525, 222/563 [51] Int. Cl B65d 4/28 [58] Field of Search 220/245, 60, 42 B;

[56] References Cited 1 UNITED STATES PATENTS 2,876,485 3/1959 Cowles 85/DIG. 2 3,521,796 7/1970 Roy......... 222/525 2,927,709 3/1960 Hoffman et a1 222/522 X Erb et al. 24/208 A Stull 222/499 Primary ExaminerRobert B. Reeves Assistant ExaminerL. Martin Attorney-Anderson, Luedeka, Fitch, Even & Tabin [57] ABSTRACT To prevent large increases in the force required to pull a sliding plunger of a dispenser closure to its open position and to prevent cold flowing of an enlarged annular sealing surface on the plunger, the annular sealing surface is located within the confines of a smaller diameter aperture when the plunger is in its closed position and blocking fluid flow. Preferably, the plunger is positively retained against popping up to the open position by a sealing ring which is deflected radially outwardly with insertion of the annular sealing surface therein and which, when deflected, exerts a gripping force on the annular sealing surface of the plunger.

1 Claim, 5 Drawing Figures PATENIEB Z FIGI FIGS PRlOR ART INVENTOE ara/d A 20y MMFLMQW mu AT T Y5.

1 SLIDING PLUNGER DISPENSING CLOSURE This invention relates to a dispensing closure for a container and more particularly to an inexpensive two piece plastic dispenser closure having a push-pull plunger slidable within a cap body between a closed position in which fluid is sealed from flow therefrom and an open position in which fluid is free-to flow through the dispensing closure.

One dispenser closure of this general kind is disclosed in U.S. Pat. No. 3,521,796 to Gerald L. Roy. This patent discloses a push-pull plunger which is slidably mounted for reciprocating within a vertical chamber in the cap body. On the upper end of the plunger is an enlarged end for gripping by the user to facilitate pulling of the plunger up to its open position in which position fluid may flow from the container through the plunger. More specifically, fluid may flow from the container through an aperture in a bottom wall of the chamber and through openings in the plunger into an interior passageway in the plunger from which the fluid may discharge from the plunger. The plunger is held by friction in its open position because of frictional engagement of plunger side walls with side walls of the chamber in the cap body. When the user pushes the plunger down to the closed position against this frictional resistance, a lower central projection on the plunger moves downwardly into the aperture in the bottom wall of the chamber to form a seal against liquid flowing into the chamber and through the passageway in the plunger.

Some early commercial forms of this kind of dispenser closure were subject to leaking as the plunger would pop up to its open position during shipping of the container from the manufacturer as a result of being shaken, vibrated, or dropped during transit. To prevent such leakage and to hold the plungers in closed position during shipping, some manufacturers positioned inserts of paperboard or corrugated board in the packaging carton between the carton cover and the topof the plunger to act as a stop preventing upward movement of the plunger from its closed position.

To prevent such leakage without the expense of additional inserts, the plunger was formed with a bead or annular sealing surface on the lower end of its central projection. The diameter of this annular sealing surface was slightly larger than the diameter of the aperture; and this plunger sealing surface was formed of a softer plastic than the plastic at the aperture in the bottom wall and cap body. Thus, it was possible to force the larger diameter sealing surface to deflect sufficiently to pass into and through the aperture. When the plunger was pushed to its closed position, the enlarged sealing surface was located partially beyond a lower corner of the aperture wall at the bottom side of the chamber wall and this engagement with the corner provided a positive retention against the plunger popping up during shipping of the container. The enlarged sealing surface wassufficiently larger in diameter than the aperture wall at the lower corner of the aperture that it provided an effective seal against leakage despite slight variations in dimensions of the aperture or sealing surface as may result from the plastic molding of the plunger and the cap body.

Dispenser closures of this kind are intended to be manually opened by housewives or others within specific restrictions as to the amount of force they need to apply to shift the plunger between its open and closed positions. For example, it is often specified that the pull on the plunger to position it in its open position should not exceed 6 to 8 pounds, preferably on the lower side a of this range. The force needed to operate the plunger should not exceed this 6 to 8 pound range particularly on the first opening operation since the plastic has had considerable time to cold flow due to the tight interference fit.

While dispensing closures of the kind described are commercially very successful, it has been observed that within this design some dispensing closures require a greater effort, i.e. force, than eight pounds to open them. In some instances, the opening force has been as much as nine pounds or greater and hence beyond the desired operating specifications for such dispensing closures.

Thus, there is a need to provide a more easily opened dispensing closure particularly for the first use thereof. As dispensing closures of this kind have met with such wide commercial success and are made by the millions each month, it is most desirable when solving the problem of reducing the effort to open the same while preventing popping up of the plunger that only minimal changes be made to the plunger, to the cap body, to the molding techniques, or to the amount of plastic needed.

Accordingly, an object of the present invention is to provide and to maintain a low, as compared to the prior art, opening force for a dispenser closure of the foregoing kind.

Other objects and advantages of the invention will become apparent from the following detailed descrip tion taken in connection with the accompanying drawings in which:

FIG. 1 is an enlarged, vertical cross-sectional view of a dispenser closure having its plunger in a closed posi tion and embodying the novel features of the invention;.

FIG. 2 is a view similar to FIG. 1 with the plunger raised to its open position;

FIG. 3 is a further enlarged fragmentary view of a prior art dispenser closure having its plunger in the closed position;

FIG. 4 is a view similar to FIG. 3 of the dispenser closure of FIG. 1 with its plunger in the closed position; and

FIG. 5 is an enlarged perspective view of the plunger shown in FIG. 1.

As shown in the drawings for purposes of illustration, the invention is embodied, very generally, in a dispenser closure 11 having a cap body 12 for attachment to a container (not shown) and a plunger 13 slidably mounted in the cap body. Upon pulling upwardly on an upper enlarged end 15 of the plunger, it shifts from a non-dispensing, lower closed position (such as illustrated'in FIG. 1) to an upper open dispensing position (such as illustrated in FIG. 2). When the plunger is raised to its open position, fluid may flow through an aperture 17 in a bottom wall 18 of the cap body into an internal chamber 19 in the cap body and therefrom into openings 20 in the plunger into an internal passageway 21 in the plunger for discharge therefrom, as is indicated by the directional arrows in FIG. 2 The plunger is frictionally held in its upper open position by the friction resistance between an outer cylindrical wall 23 of the plunger and an interior cylindrical wall 24 of the cap body.

In the prior art, as will be described in connection with the illustrationof FIG. 3, the plunger 13a was held against popping upwardly to its open position during shipment of the dispenser closure 1 1a (a suffix a having been added to the reference characters for prior art elements of FIG. 3 to distinguish them from corresponding elements shown in the other figures of the drawing). The plunger 13a has an enlarged sealing surface 25a on a projection 27a on its lower end for moving through the aperture 17a to and at least partially beyond a lower corner 29a of the aperture. 17a. The sealing surface 25a has a larger diameter than the diameter of the aperture 17a but is formed in such a manner that it is able to deflect and deform to decrease its diameter to the extent it may pass through the aperture 170.

The plunger 13a was formed of a plastic material such as polyethylene which is softer than the plastic material for the cap body 12a which was a polypropylene plastic material. The diameter of the annular sealing surface 25a on the lower edge of the plunger 13a was sufficiently larger than the diameter of the aperture 17a that a fluid tight seal was maintained despite variations in dimensions for the aperture 17a or the outer diameter of the sealing surface 25a, such variations being within normal tolerances for plastic molding operations. Additionally, the larger diameter sealing surface 25a when it was abutting the lower corner 29a of the bottom chamber wall positively retained the plunger 13a in its closed position against popping up and leaking during shipping of the containers.

While dispensing closures of the kind shown in FIG. 3 provided the necessary fluid tight seal and retained their plungers 13a in the closed position, they occasionally failed to open upon exertion of 6 to 8 pounds of pulling force, particularly when used for the first time.

It has now been discovered that with such prior art constructions, the large pulling forces required on first use thereof were the result of the annular sealing surface 25a being cold flowed and permanently deformed into a larger diameter with the consequence that forces larger than the operating specifications were required to deflect the larger diameter sufficiently for it to pass through the aperture 17a. More specifically, when the plunger 13a was larger than the aperture 17a the plastic cold flowed and deformed, much in the manner shown diagrammatically in FIG. 3, by the dashed line 25b. With increased time, the annular surface 25a flowed and became larger in diameter and began to approach the configuration outlined by dashed line 25b. The sharp edge 29a then became an obstacle to lifting the plunger.

In accordance with the present invention, the problem of a large initial opening force for the dispenser closure is solved by locating the sealing surface 25 on the plunger 13 within an aperture defining wall 30 and preferably within a deflectable retaining and sealing corset-or ring 32 formed on the underside of the bottom wall 18. More specifically, the sealing surface 25 has a larger diameter than the internal diameter of the lower portion of the aperture wall 30 which lower portion is within the ring 32; and this larger sealing surface 25 flexes the thin cross section ring 32 circumferentially outwardly and it, in turn, exerts a circumferential gripping force on the sealing surface 25 thereby positively' retaining the'plunger against popping open while, at the same time, providing a fluid tight seal despite variations in the dimensions thereof. The softer plastic of the larger diameter sealing surface 25 on the plunger may deform and be in compression with the aperture defining wall 32 but it is not being expanded beyond a sharp shoulder such as shoulder 29a and increasing it diameter.

Because the relatively thin cross section ring 32 is not rigidly backed by the bottom wall 18, the harder polypropylene plastic of the ring 32 may flow slightly as a result of being under load from the compressed sealing surface 25. After a period of time under such a load, the plastic of the ring 32 may actually flow radially outwardly from the sealing surface 25 and form a slightly enlarged, reversely tapered, opening in the ring 32 extending to the upper portion of the aperture 17 within the more substantial mass of the bottom wall 18.

Also, as will be explained in greater detail, the addition of the sealing and retaining ring 32 solves the problems involved and necessitates relatively little reworking of tooling or addition of plastic material to the prior art dispenser closure. More particularly, only a small amount of metal need be removed from molds previously used to make the prior art cap bodies in order to form a ring 32 on the cap bodies molded therein.

Referring now in greater detail to the illustrated cap body 12, it is formed in one piece by molding an elastomeric plastic such as polypropylene. The cap body is formed with a generally horizontally disposed circular top wall 36 with a depending cylindrical skirt 38 integrally attached to an outer circumferential edge of the top wall 36. To thread the cap body onto an external thread on a container, such as a detergent bottle, internally molded threads 39 are formed on the inner side of the skirt. Spaced inwardly from the skirt and disposed generally centrally within the cap body is a projection or barrel 40 which is comprised of a lower barrel section 41 of closed cylindrical shape depending from the top wall 36 and an upper barrel section 42 of cylindrical shape projecting upwardly above the plane of the top wall 36. The bottom wall 18 of the chamber 19 closes the bottom of lower barrel section 41 except for the aperture 17 therein.

The plunger 13 is inserted into the hollow interior of the barrel 40 and its outer cylindrical wall 23 frictionally engages the internal cylindrical wall 24 of the barrel. The internal cylindrical wall 24 is formed with an upper surface 44 in the upper barrel section 42 which is smaller in diameter than a lower surface 45 of the lower barrel section. The frictional engagement between these internal barrel surfaces 44 and 45 and the plungers outer cylindrical wall 23 holds the plunger 13 in its upper open position (until the same is pushed downwardly to the closed position by a manual force) and prevents fluid escape along the interface between the same. These frictional forces also help resist the popping up of the plunger 13 to the open position during transit. However before the enlarged sealing surface 25a was added and retained by the shoulder 29a, dispenser closures having these frictional resisting forces between the barrel and plunger still popped open. It appears that the clearances between the plunger cylindrical wall 23 and the internal barrel surfaces 44 and 45 become so large, in some instances, that they will not retain the plunger in its closed position during transit.

As will be observed, the plunger 13 has its wall 23 formed with a lower portion 47 of a diameter larger than the diameter of its upper portion 48. To insert the larger diameter portion 47 of the plunger through the smaller bore in the upper barrel section 42 during assembly of the dispensing closure 11, the plunger 13 is pushed with considerable force to flex the wall of the upper barrel section 42 radially outwardly while the large plunger portion 47 is in compression and deflected slightly to pass into the large diameter bore in the lower barrel section 41.

When assembled, the plunger 13 will be held against disassembly from the cap body 12 because of abutment of inclined stop shoulder 49 in the barrel with a stop shoulder 50 on the plunger. Preferably, as best seen in FIG. 2, the plunger stop shoulder 50 is inclined downwardly and radially outwardly as is the complementary stop shoulder 49 on upper section 42 of the barrel-like projection. It is only with a tremendously greater exertion of upward force on the plunger 13 than is needed to pull the plunger to its open position may one deflect the plunger 13 and the wall of the upper barrel section 42 sufflciently to pull the plunger 13 upwardly past the stop shoulder 49 to separate the plunger 13 frorn the cap body 12.

The plunger 13 is stopped in its lower closed position, as best seen in FIG. 1, when a lower stop shoulder 52 on the lower barrel section 41 of the plunger abuts a stop shoulder 54 adjacent the bottom wall 18 for the chamber 19. When the stop shoulders 54 and 52 abut, it is preferred that an audible click be made to signal audibly to the user that the plunger 13 is closed and prevents further fluid flow. The bottom wall 18 of the chamber 19 is formed at the lower end of the lower barrel section 41.

The preferred sealing ring 32 is readily formed with the same molds, which heretofore made the conventional cap bodies without the ring 32, by removing a small annular ring of metal from the mold to form an annular groove which will fill with plastic material at the location of the removed metal. By way of example only, the illustrated aperture 17 is formed with a constant diameter of 0.121 inch throughout its length. The illustrated aperture extends vertically about.0.060 inch from a lower corner 29 at a bottomside 58'(FIG. 4) of the sealing and retaining ring 32 to an upper corner 60 formed at the juncture of the aperture'defining wall 30 and a flat upper side 62 of the bottom wall 18. The portion of the aperture 17 within the sealing and retaining ring 32 may be quite small, for example, 0.023 inch from the lower corner 29 of the aperture 17 upwardly to a lower side 59 of the bottom wall 18.

The sealing and retaining ring 32 is much more pliable than the remainder of the bottom wall 18 because of its thin cross sectional thickness and because the lower end thereof is free of attachment to a rigid backing wall. The illustrated ring 32 is about 0.26 inch in thickness with an internal aperture diameter of 0.121 inch and an outer diameter of 0.173 inch.

As stated previously, the retaining and sealing ring 32 deflects to have a generally reverse tapered wall when in engagement with the annular sealing surface 25, as is diagrammatically illustrated in FIG. 4. That is, the aperture wall 30 within the ring 32 is deflected to have a large diameter beneath an upwardly located smaller diameter in the aperture wall 30. This provides the gripping and positive retention of the plunger against popping open.

To provide a fluid tight seal irrespective of dimensional tolerance variations, the annular sealing surface 25 on the plunger 13 has a maximum outer diameter considerably larger than the diameter of the aperture 17 and it is preferred that the diameter of a cylindrical shank on the plunger projection 27 carrying the enlarged sealing surface 25 also have a diameter larger than that of the aperture. By way of example only, the sealing surface 25 may have a non-deflected diameter of 0.137 inch for insertion into the 0.121 inch diameter aperture. The illustrated cylindrical shank 70 of the plunger projection 27 has a diameter of 0.129 inch.

To facilitate insertion of the plunger 13 into the aperture 17 when moving the plunger 13 from the open to the closed position, the lower tip of the plunger projection 27 beneath the sealing surface 25 is tapered downwardly and inwardly therefrom to a plunger end wall 71 which is sufficiently small to readily pass into and through the aperture 17. More specifically, the illustrated plunger projection has a tapered wall 73 preferably tapered at 30 to the vertical.

The illustrated plunger 13 is of generally tubular construction and molded from an elastomeric plastic such as polyethylene which is softer than the polypropylene of the cap body 12. The enlarged upper end 15 of the plunger is formed with an outwardly extending flange 74 which projects above and radially outward of the upper barrel section 42 sufficiently to permit the fingers of the user to be positioned therebeneath to exert an upward lifting force on the underside of the enlarged end 15. Preferably, the .top of the plunger is a concave surface 75 to accept more readily the curvature of a finger or thumb pushing downwardly on the top of the plunger, and to provide a drain back feature for the liquid product.

Within the bore or passageway 21 of the plunger, several retention rings or ribs 76 are formed. As best seen in FIG. 5, a transverse horizontal web 78 extends across and defines the bottom of the passageway 21 in the plunger and supports the attached cylindrical shank 70 of the plunger projection 27. The openings 20 in the plunger are longitudinally extending in the lower larger diameter portion 47 and extend upwardly from opposite sides of the web 78 and through the tubular wall of the plunger to the internal passageway 21.

When the plunger 13 is in its upper open position, as shown in FIG. 2, the annular sealing surface 25 and the plunger bottom wall 71 are spaced above the upper corner 60 of the aperture 17 in the bottom wall 18 allowing fluid to flow through the openings 20 into the internal passageway 21 to discharge.

Briefly, operation of the dispenser closure 11 will be given to aid in understanding the foregoing. With the plunger 13 in its closed position, the user will place his fingers beneath the enlarged upper end 15 of the plunger and pull upwardly to raise the plunger from the closed position, such as illustrated in FIG. 1, to the open position, such as illustrated in FIG 2. In its closed sure. By having the annular sealing surface 25 within the aperture 17 and within the sealing ring 32, the sealing surface 25 is prevented from cold flowing against a lower corner 29 at the bottom of the aperture 17 as occured with the prior art construction, as is illustrated in FIG. 3. As the plunger is thus prevented from cold flowing to the larger diameter, the opening force requirement may be maintained within the desired level of 6 to 8 pounds, in this instance, even though the dispenser closure 11 has been unused for a long period of time.

The upward movement of the plunger 13 is limited by the engagement of the upper plunger stop shoulder 50 abutting the stop shoulder 49 of the upper barrel section 42 of the cap body. At the open position, the plunger projection end wall 71 is spaced above the upper side 62 of the chamber bottom wall 18 leaving the aperture 17 open to fluid flow from the container. Fluid may flow from the aperture into the chamber 19 and then through the openings 20 in the plunger into the passageway 21 to exit therefrom at the enlarged upper end of the plunger, as indicated by the directional arrow in FIG. 2. The plunger will remain in this upper position due to a frictional contact between the cylindrical plunger wall 23 and the internal surfaces 44 and 45 of the barrel sections 41 and 42 of the cap body.

From the foregoing it will be seen that the present invention provides a dispensing closure with a plunger and cap body in which the problem of cold working of a sealing surface and causing an increase in opening force have been solved in a relatively inexpensive manner. In the illustrated embodiment of the invention, a relatively small amount of plastic is added to the bottom wall of the chamber to provide a deflectable ring at the bottom of the aperture to positively restrain the plunger in itsclosed position. Thus, the plunger may be prevented from popping open and prevented from cold flowing and causing an increasing opening force for the plunger.

While a preferred embodiment has been shown and described, it will be understood that there is no intent to limit the invention by such disclosure but, rather, it is intended to cover all modifications and alternate constructions falling within the spirit and scope of the invention as defined in the appended claims.

What is claimed is:

1. A plastic dispenser closure for a container comprising a molded plastic cap body having an elongated internal chamber, a bottom wall for said chamber formed in said cap body, an uninterrupted continuous wall defining an aperture in said bottom chamber wall for permitting to flow into said chamber from said container, a tubular push-pull plunger of plastic material having an internal fluid passageway and slidably mounted in said internal chamber for vertical movement between an upper open position in which fluid may flow through said aperture in said passageway and a lower closed position in which fluid flow is blocked from flowing through said aperture, an upper enlarged end on said plunger projecting outwardly beyond said cap body for easy gripping by said user to enable the user to pull the plunger to said open position and to push said plunger to said closed position, a centrally downwardly extending plunger projection on the lower end of said plunger aligned for movement into and within said aperture, a shank on said plunger projection having a diameter larger than that of said aperture, a freely deflectable ring formed on the lower side of said bottom chamber wall and projecting downwardly therefrom and having said aperture defining wall thereon, said bottom chamber wall having a predetermined cross-sectional thickness and the downwardly projecting ring adding thereto an additional crosssectional thickness, said bottom chamber wall being rigid as compared to said deflectable ring, an annular sealing surface on said shank of said plunger projection having a diameter larger than said shank diameter for movement into said freely deflectable ring and into sealing engagement therewith, engageable stop surfaces on said plunger and on said cap body stopping said annular sealing surface from moving through said aperture and cold flowing on a lower shoulder of aper-.

ture during upward movement of said plunger to said open position, said plunger projection sealing surface deflecting said ring radially outwardly when in said closed position and said deflected ring gripping and positively retainingsaid plunger against popping open.

Claims (1)

1. A plastic dispenser closure for a container comprising a molded plastic cap body having an elongated internal chamber, a bottom wall for said chamber formed in said cap body, an uninterrupted continuous wall defining an aperture in said bottom chamber wall for permitting to flow into said chamber from said container, a tubular push-pull plunger of plastic material having an internal fluid passageway and slidably mounted in said internal chamber for vertical movement between an upper open position in which fluid may flow through said aperture in said passageway and a lower closed position in which fluid flow is blocked from flowing through said aperture, an upper enlarged end on said plunger projecting outwardly beyond said cap body for easy gripping by said user to enable the user to pull the plunger to said open position and to push said plunger to said closed position, a centrally downwardly extending plunger projection on the lower end of said plunger aligned for movement into and within said aperture, a shank on said plunger projection having a diameter larger than that of said aperture, a freely deflectable ring formed on the lower side of said bottom chamber wall and projecting downwardly therefrom and having said aperture defining wall thereon, said bottom chamber wall having a predetermined cross-sectional thickness and the downwardly projecting ring adding thereto an additional cross-sectional thickness, said bottom chamber wall being rigid as compared to said deflectable ring, an annular sealing surface on said shank of said plunger projection having a diameter larger than said shank diameter for movement into said freely deflectable ring and into sealing engagement therewith, engageable stop surfaces on said plunger and on said cap body stopping said annular sealing surface from moving through said aperture and cold flowing on a lower shoulder of aperture during upward movement of said plunger to said open position, said plunger projection sealing surface deflecting said ring radially outwardly when in said closed position and said deflected ring gripping and positively retaining said plunger against popping open.

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