CROSS-REFERENCE TO RELATED APPLICATIONS
- STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
- FIELD OF THE INVENTION
This invention relates to containers for liquids, to lids for such containers and, more specifically, to replaceable, leak resistant lids for containers or cups having a generally cylindrical or frusto-conical shape.
- SUMMARY OF THE INVENTION
Although the invention described herein is particularly suitable for application to beverage drinking cups, a person skilled in this art readily may apply the invention to other similar containers which require a removable, leak resistant lid.
In accordance with the present invention, a highly leak resistant “sipper” lid suitable for paper beverage cups is provided. The unintentional passage of liquid between the mating surfaces of a cup and a lid is effectively suppressed. This feature meets consumer expectations in that, when consumers purchase drinks in cups with lids applied, they expect the cup/lid combination to prevent leakage between the mating surfaces when the cup is inclined for drinking. However, many designs fall short of this important objective.
A particular problem arises in connection with some containers which are formed such that each of their side wall and rim are formed into a closed vessel by overlapping the material (relatively thick paper) at a joint or seam. When a lid having a spout or orifice for drinking is placed over such a thick seam, there is a tendency for leakage out of the lid in that area of the rim. One approach to this problem has been to attempt to educate customers to orient the lid on the cup so that the drinking orifice is diametrically opposite the joint or seam, thereby placing the leakprone area above the level of liquid in the cup when drinking is in progress. This approach is not entirely successful since many users do not receive, understand or remember this instruction.
In accordance with one aspect of the present invention, a lid adapted for use in connection with a container for liquids comprises a generally annular mounting ring or channel for sealably engaging an upper edge or rim of a container, an annular skirt extending downwardly from the mounting ring over an outer wall of the container, an annular flange extending radially inwardly from the mounting ring and an annular, upstanding wall extending from a radially inner extremity of the flange to a generally annular plateau. The plateau, in turn, is connected to a central region which serves to form a closed lid structure. A drinking orifice typically is provided in the plateau region.
BRIEF DESCRIPTION OF THE DRAWING
The annular mounting ring is complementarily configured with respect to the container with which it is to be combined so as to provide a plug fit against the inner wall of the container and to engage the rim thereof to provide a desired leak resistant seal. These and other objects and advantages of the present invention will become apparent from the following detailed description in conjunction with the accompanying drawings.
In the drawings:
FIG. 1 is a front elevation view of a cup or container having one form of a lid in accordance with an embodiment of this invention;
FIG. 2 a is a plan view of a particular lid according to a preferred embodiment of the invention;
FIG. 2 b is a cross-sectional view taken along the line B-B′ of FIG. 2 a;
FIG. 2 c is a partial cross sectional view showing a stack of two of the lids of FIG. 2 a;
FIG. 3 is a partial, enlarged cross-sectional view of the portion of the lid enclosed in a dashed circle in FIG. 2 b, showing relationships between the lid and container;
FIG. 4 is a partially cut away elevation view of one type of standard container suitable for use in connection with this invention;
FIGS. 5 a, 5 b and 5 c are views similar to those shown in FIGS. 2 a, 2 b and 2 c of a second embodiment of the invention; and
DESCRIPTION OF ILLUSTRATIVE EMBODIMENT OF THE INVENTION
FIG. 6 is a partial, enlarged cross-sectional view of the portion of the lid enclosed in a dashed circle in FIG. 5 b.
Referring to FIG. 1, a typical container or cup assembly 10 suitable for beverages and being formed from paper, plastic, plastic foam or the like, in a generally cylindrical or frusto-conical shape, is shown. A lid 12 constructed according to the present invention is shown sealably mounted at the top of container 10. Lid 12 (other forms of which are shown in greater detail in others of the figures) preferably is produced by thermoforming a thin, flat sheet of clear or opaque (black, white or colored) plastic such as polystyrene onto a lid mold to form the desired lid shape which will be explained below. The lid may also be formed by injection molding while maintaining the desired properties and characteristics as set forth hereinafter. The thickness of the plastic for the lid typically is about 0. 017 inches in its finished form.
The container 10 typically is a paper cup suitable for hot or cold beverages and will be referred to hereinafter as cup 10. As is customary, such cups have a substantially tubular (circular cross section) bead 14 (see FIG. 4) formed at their upper edge and extending radially outwardly from the generally cylindrical or conical upright wall 16 of the cup.
As can be seen in FIGS. 2 a-3, lid 12 comprises a generally inverted U-shaped sealing channel 18 having a cross-section (FIG. 3) with an interior wall 22 of generally the same curvilinear to straight shape as the combination of the outer extremity of bead 14 and the upper end of the wall 16 of cup 10. More specifically, on lid 12, the outer (maximum diameter) portion 20 of channel 18 is generally tubular in shape and it transitions smoothly into a substantially vertical, straight, inclined inner wall member 24 which is outwardly inclined at its upper end. Wall member 24 is inclined at substantially the same angle A (e. g. 6.25 degrees) as the wall of the cooperating cup 10. Inner wall member 24 is adapted to extend downwardly inside wall 16 of cup 10 in a “plug fit” relationship.
A negative clearance or plug interference fit such as 0.04 inches for a cup 10 having a specified maximum outside bead diameter of 3.54 inches is provided between the inner wall 24 of channel 18 and the inner surface 16′ of wall 16 of cup 10. This deep inside plug fit provides the desired surface area contact for sealing the interface between the adjacent surfaces of lid 12 and cup 10.
In addition, at a sloped transition region 28 between a lower extremity of channel 18 and an upper extremity of a skirt 32, an undercut or reentrant wall 30 is provided which has an minimum inner wall diameter, for example, 0.05 inches less than the maximum inner wall diameter 30 of channel 18 as best seen in FIG. 3 (“0.025 UNDERCUT”).
A lowermost inner corner 26 of inclined inner wall 24 is shown having a diameter of 3.25 inches. As shown in FIG. 4, the outermost diameter of the rim bead 14 for a corresponding cup 10 has a nominal value of 3.54 inches. The bead 14 itself is specified as having a nominal diameter of 0.14 inches. It can therefore be seen that the maximum opening at the top of cup 10 (measured at the uppermost point on rim bead 14 where the inner surface 16′ of cup wall 16 begins to slope downward and inwardly) is nominally 3.54 inches minus 0.14 inches or 3.50 inches. The lowermost inner corner 26 of inclined wall 24 of channel member 18 therefore will fit into the top of rim bead 14 with a clearance of about 0.07 inch on each side (diameter is nominally 0.14 inches smaller).
The inward slope of the inner surface 16′ of wall 16 (for example, nominally 6.25 degrees in some cups and 5 degrees in others), and the dimensions of cup wall 16 and inclined wall 24 of channel 18, are arranged so that the lowermost inner corner 26 of channel 18 will come into contact with the inner surface 16′ of cup wall 16 before the lid 12 is fully seated on the top of rim bead 14. In addition, the largest unstressed diameter inside the curvilinear portion 22 of channel 18 is typically selected to be 3.50 inches, a dimension approximately 0.04 inches less than the nominal largest diameter of rim bead 14. This arrangement provides a negative (or interference) snap fit of the channel 18 over rim bead 14. Thus, as the lid 12 is placed on cup 10, the lower edge of a skirt region 32 (e.g. 3.55 inch diameter) of lid 12 passes over rim band 14 until sloped transition region 28 engages rim band 14.
Skirt region 32 is then bowed outwardly as pressure is applied to the top of lid 12 until undercut 30 snaps over rim band 14 of the cup 10. As additional pressure is applied around the entire top of lid 12, the inner surface 22 of the upper curvilinear region of channel 18 seats along the top of rim bead 14 and the lowermost corner 26 of inclined wall 24, along with a portion of wall 24, forms an interference or plug fit seal against the inner surface 16′ of wall 16 of cup 10.
It should be noted that the height from the lowermost corner 26 of wall 24 to the upper curvilinear portion 22 of channel 18 is arranged, in combination with the several diameters mentioned, to provide the desired result of a leak resistant seal between cup 10 and lid 12.
Proceeding radially inwardly from the lowermost corner 26 of wall 24, in the embodiment shown in FIGS. 2 a-3, a substantially flat, concentric reinforcing web or flange 36 extends radially inwardly from channel 18 towards the center of lid 12 to a lower extremity of an inwardly inclined upstanding outer wall 38 of a central plateau region 40. As shown in FIGS. 2 b and 2 c, wall 38 extends from the lowermost to above the uppermost extremity of sealing channel 18 (and rim bead 14) so that plateau region 40 is displaced vertically above sealing channel 18. The top surface 42 of plateau region 40 may be inclined as shown in FIG. 2 b. A downwardly extending eccentric wall 44 extends from the top surface 42 to a closed center web section 46 of lid 12. Center web section 46 may be flat, concave or convex but preferably is concave as shown. The top surface 42 of plateau region 40 is provided with a drinking orifice 48 shown as an oval hole in the highest and widest region of plateau region 40. As should be apparent from FIG. 2 b, this location of orifice 48 provides a maximum height and width for the portion of plateau 40 from which liquid is emitted to the person drinking from the cup 10. The orifice 48 may therefore be sized appropriately for comfortable consumption of the liquid.
Taking into account the necessary height for wall 24 in order to provide a good seal around channel 18, stiffening or reinforcing members such as hollow domes 34 (FIGS. 2 a-3) or hollow elongated ridges or ribs 34′ (FIGS. 5 a-6) molded in the radially extending flange 36, or their equivalent, are provided to prevent deformation of the flange 36 and to maintain the required diameter at the lowermost corner 26 (or 26′) for a continuous interference fit when the lid 12 is plug fit into cup 10.
In an alternative embodiment of the invention shown in FIGS. 5 a-6, reference numbers for corresponding elements are numbered the same as in the preceding figures but are followed by a ′ (prime symbol). The alternative arrangement also illustrates a different set of dimensions for use in connection with a cup having a maximum diameter at its top of 3.66 inches and a rim bead of 0.18 inches. As can be seen by referring to FIGS. 5 a-6, certain of the elements shown in those figures are eccentrically positioned to a greater extent than is the case in the embodiment shown in FIGS. 3 a-4. One result of such greater eccentricity is that reinforcing flange or web 36′ occupies a greater area than the area occupied by reinforcing flange 36 in the FIG. 3 a-4 embodiment. This is particularly evident in the portion of reinforcing flange 36′ which is diametrically opposite the portion thereof between the drinking orifice 48′ and the outer edge of lid 12′.
In order to maintain a desired stiffness in flange 36′ so as to hold wall 24′ of lid 12′ in firm, sealing relationship against the adjacent inner surface 16′ of cup 10, the reinforcing dimple members 34′ are elongated radially to the form of ribs of increasing length proceeding circumferentially away from drinking orifice 48′. It should be noted that, in at least a portion of the flange 36′, where the horizontal dimension of flange 36′ may be small, the upstanding walls adjacent the flange are close to each other and there is no need (or space) for the reinforcing dimples, domes or ribs.
It should also be noted that the embodiment shown in FIGS. 5 a-6 also includes an elongated skirt having an additional transition member 50′ which will bring the lowermost member 32′ of the skirt further outward and along the side of cup 10.
Significant advantages of a lid according to the present invention are realized from the inside plug fit of the innermost wall of the sealing channel and cup wall, the relatively long single or multiple step outside skirt and the radial reinforcing slots or dimples in the reinforcing flange which maintain the sealing channel in contact with the cup wall. That is, the radial slots/dimples provide added interior support for the plugged lid surface and assist in holding the plug fit surface area of the lid in contact with the cup wall surface. The deep inside plug fit provides added surface area contact with which to seal the lid surface to the cup wall surface, thus preventing leakage between the surfaces. The outer skirt design, in conjunction with the reinforced deep plug, allows higher rim to lid interference levels which assist in preventing distortion on the outer portion of the lid, while applying more pressure to the cup rim.
The desired results are a greater lid to cup rim contact area, thus suppressing the flow of liquid between the lid and cup rim.
In view of the foregoing description, numerous modifications and alternative embodiments of the invention will be apparent to those skilled in the art. Accordingly, this description is to be construed as illustrative only and is for the purpose of teaching those skilled in the art the best mode of carrying out the invention. Details of the structure may be varied substantially without departing from the spirit of the invention.