Screw cap core seal structure

Abstract

A screw cap for a container is disclosed, which includes a screw cap body (10) and an expandable core seal (24) with an annular sealing element (30). A peripheral portion (36) of a seal energizing element (38) is radially expanded when the screw cap body (10) is threaded onto the container. The peripheral portion (36) is joined to a backing (34) of the annular sealing element (30), which includes a plurality of independent axially extending segments (42, Fig. 4). Thereby, axial compression of the seal energizing element (38) not only causes adjacent portions of the sealing element (30) to tend to radially expand, but also causes the axially extending segments (42) to tend to rotate upwardly and outwardly. This results in a more uniform distribution of sealing pressure of the annular sealing element (30).

Description

Technical Field

[0001] This invention relates to screw caps for containers. More specifically, this invention relates to screw caps provided with a core seal that expands to engage the inner surface of the container neck. Background Technology

[0002] Various forms of such expandable core seals are known from GB2280895. In one form shown, the expandable core has a face sealing ring that rests against the edge of the container neck during use, and a central section protruding from the face sealing ring when the core is in a relaxed (shrunken, unsealed) state. Thus, the central section of the expandable core rests against the inner surface of the top wall of the cap applied to the container neck. A slightly flexible outer skirt typically hangs vertically from the inner edge of the face sealing ring to rest against the inner surface (bore) of the container neck during use. A flared (trumpet-shaped) inner skirt connects the lower periphery of the outer skirt to the outer periphery of the central section. At least the lower outer periphery of the inner skirt has some flexibility. When the cap is applied to the container neck, the face sealing ring rests against the edge of the container neck. Then, as the cap moves further axially onto the container neck, the central section of the core seal continues to move axially into the container neck with the cap. The engagement of the face sealing ring with the edge of the container neck restricts axial movement of the lower peripheries of the outer and inner skirts relative to the container neck. Therefore, continued application of the cap causes compression and collapse of the lower periphery of the inner skirt and corresponding radial expansion. This radial expansion causes corresponding radial expansion of the outer skirt, particularly at and towards its lower (inner) end. Thus, the outer skirt expands to form a sealing engagement with the inner surface of the container neck.

[0003] In another form shown in GB2280895, the inner skirt has a shallow truncated conical shape and is apparently connected to the lower periphery of the outer skirt and the outer periphery of the central section via corresponding outer and inner circumferential hinges. The cap top wall is fixed to the central section of the expandable core. In the relaxed, contracted, and unsealed state of the core seal, the outer circumferential hinge is positioned below the inner circumferential hinge. When the cap is applied to the container neck, the shallow truncated conical inner skirt begins to flatten, thereby resisting the application of the cap, and expands at least the lower portion of the outer skirt again toward the inner surface of the container neck, and then seals against the inner surface of the container neck. When the inner skirt has been twisted into a generally flattened shape, it reaches an "over-center" state, in which it quickly snaps into an outward-folding shape, with the inner circumferential hinge positioned below the outer circumferential hinge. This pulls the top wall of the cover toward (or, in the absence of any other cover-to-neck fasteners, toward) the face seal ring and the edge of the container neck; the trade-off is some loosening of the seal on the outer skirt.

[0004] This expandable core seal can be used to seal a conventional internally screwed cap to a conventional externally screwed container neck. The outer skirt can have a facing layer made of a relatively flexible material to compensate for any irregularities on the inner surface of the container neck and to abut against it for a seal. The backing structure for the outer skirt and the entire inner skirt can be formed of a relatively stiffer, more creep-resistant material. A final torque limit (“target torque”) can be selected, which ensures that the facing layer deforms appropriately to achieve a fully circumferentially sealed engagement with the inner surface of the container neck. At this torque, there will be significantly more deformation in the inner skirt than in the facing layer of the outer skirt. Therefore, expansion of the container neck, for example due to temperature increases, or thinning of the facing layer due to creep, does not result in any significant relaxation of the ability to press the facing layer against the inner surface of the container neck and maintain its sealing contact with the inner surface of the container neck. If the cap is screwed to a torque higher than that required to achieve a good circumferential seal in the first place, the excess strain is largely absorbed by further deformation of the inner skirt. This protects the finish layer from excessive tension, improper twisting, and compression. Therefore, the expansion core container cap seal disclosed in GB2280895 has good fault tolerance to prevent poor neck inner surface finish and inaccurate tightening torque.

[0005] The possible radial expansion of the outer skirt is limited by the elastic limit of the material forming the outer skirt. For the two types of expandable core seals mentioned above, the maximum expansion of the outer skirt also largely depends on the distance the central section protrudes above the face seal ring when the core is in a relaxed state, or the axial distance between the inner and outer circumferential hinges when the core is in a relaxed state.

[0006] In the case of screw-on threaded container caps, the expansion of the expandable core seal from a relaxed, fully contracted, unsealed state to a sealed state preferably occurs during the last few turns of the screw cap (or even within a small portion of the last turn). This ensures that when the cap is tightened to the target torque, it is in a predictable axial position where the length of the cap and neck threads is sufficient to engage with each other. This results in a secure interconnection between the cap and the container, preventing the cap from "bursting off" under rough handling or internal pressure, for example, due to heating or agitation of the container contents releasing gas, or storing or transporting containers at least partially filled with gas at low environmental pressures (such as in aircraft or at high altitudes). Accurate final axial positioning of the cap is also generally necessary to ensure proper engagement and safe operation of the cooperative tamper-evident features respectively located on the cap and the container neck. Therefore, the face seal ring is axially positioned relative to the screw cap such that it contacts the edge of the container neck, and the expansion of the outer skirt only begins when the screw cap has less than one turn remaining (or, in the case of a screw cap with fine threads) before it is fully screwed onto the container neck. Therefore, the necessity of this arrangement further limits the possible expansion range of the core seal. Sometimes, especially in cases where the container neck is excessively large (exceeding tolerances, as may happen, for example, in the case of blow-molded containers, where the neck inner diameter varies considerably; and / or because nominal standard manufacturing dimensions actually differ between different manufacturers), the available expansion range of the core seal is insufficient to form a reliable seal inside the container neck bore. On the other hand, if the core is allowed to begin expanding many turns before the cap is fully screwed on, the possible expansion range of the core seal increases, but the final axial position of the screw cap becomes unacceptably unpredictable when the target torque is reached.

[0007] WO2020 / 200619 discloses a screw cap and core seal arrangement in which a resiliently deformable sealing activating element is rotatably connected to an end wall of the cap body. This connection includes a cam surface that converts the relative rotation between the cap body and the sealing activating element into axial movement of the sealing activating element when the cap body is screwed onto the container neck. This axial movement is added to the movement of the end wall of the cap body when the cap is screwed onto the container neck. Therefore, when the cap is twisted to its final fully screwed-on position on the container neck, the cap can provide a highly expandable core seal that requires very little rotation to operate.

[0008] However, the resiliently deformable sealing element disclosed in WO2020 / 200619 again primarily (if not exclusively) acts on the lowermost end of the sealing element located within the container neck. According to one embodiment, if a more uniform loading of the sealing element is required, the relatively upper end of the sealing element (closest to the opening of the container neck) can be expanded outward by a separate annular wall, optionally overhanging from the inner surface of the cap body end wall. The inclined section at the upper end of the sealing element is forced to expand radially because it is pushed against the overhanging annular wall during the final tightening of the screw cap body onto the container neck. Rotational slippage between the resiliently deformable sealing element and the container neck may also hinder the effective operation of the core seal of WO2020 / 200619.

[0009] US3788510 relates to a cap gasket that can be energized to surround the upper edge zone of a container neck. The upper portion of the annular wall portion of the gasket is energized by a shallowly tapered web, the apex of which is pushed downward by the inner face of the cap end panel. The lower edge of the wall portion has a hook-like profile, including a downwardly sloping and outwardly pointing face and an upwardly facing inner shoulder. This upwardly facing shoulder sealably engages, substantially perpendicular to the main axis of the neck, with a downwardly facing flat shoulder within the neck portion. The base of the tapered web is located away from the hook-like lower edge of the wall portion and therefore has little capacity to expand or provide a tighter seal between the shoulders. The conformability of the wall portion to the container neck and the flexibility necessary for a seal against the container neck also mean that stress and strain at the base of the tapered web remain confined there. Summary of the Invention

[0010] The present invention aims to alleviate at least some of these problems, and therefore provides a screw cap comprising:

[0011] A cover body, the cover body including an end wall and an internally threaded annular side wall hanging from the end wall;

[0012] An annular sealing element is concentrically disposed within and spaced apart from the annular sidewall so that when the screw cap is screwed onto the neck of the container, the annular sealing element can be received within the externally threaded neck of the container.

[0013] A stop portion that can engage with the container neck so as to support the annular sealing element inside the container neck when the screw cap is screwed onto the container neck;

[0014] An elastically deformable sealing element includes a central portion supported against an end wall of a cap body and a peripheral portion connected to an annular sealing element. The sealing element is constructed and operably arranged within the cap body such that when the cap body is screwed onto the neck of a container, axial compression of the sealing element between the central portion and the peripheral portion causes radial expansion of the sealing element at the peripheral portion, thereby causing the annular sealing element to expand radially toward the inner surface of the container neck.

[0015] The annular sealing element includes a backing made of a relatively rigid but elastic material and a finish made of a relatively more flexible material, wherein the backing extends in a direction away from the end wall of the cover body below the horizontal plane of the stop;

[0016] Its features are:

[0017] The peripheral portion of the sealing element is connected to the backing at or below the stop at a horizontal plane, and the backing below this horizontal plane comprises multiple independent axially extending segments. With this arrangement, axial compression of the sealing element not only causes the peripheral portion of the sealing element and adjacent portions of the sealing element to expand radially, but also causes these axially extending segments to rotate upwards and outwards. Both of these tendencies are resisted by the surrounding container neck when the cap is screwed onto the container neck. The upward and outward rotational tendency of the backing segments, when added to the radial expansion tendency of the annular sealing element at the horizontal plane of the sealing element's periphery, results in a more uniform distribution of sealing pressure across the entire axial range of the sealing element against the inner surface of the container neck. This improves the sealing performance of the sealing element. If the cap is screwed to a torque higher than that required to achieve a good circumferential seal in the first place, the excess strain is largely absorbed not only by further deformation of the sealing element, but also by bending stress in the segments of the backing. This protects the finish from excessive tension, improper twisting, creep relaxation, and compression. Therefore, the screw cap of the present invention has excellent sealing performance and fault tolerance to prevent poor neck inner surface finish and inaccurate tightening torque.

[0018] The sealing element, annular sealing element, stop, backing, and finish may include portions of an expandable plug sealing subassembly within the screw cap. The plug sealing subassembly and cap body may include a snap-fit ​​connection that retains the plug sealing subassembly within the cap body even when the screw cap is not screwed onto the container neck. The snap-fit ​​connection may include a recess at the center of the sealing element, into which a protrusion extending from the end wall of the cap body snaps fits. The protrusion may include a plurality of axially extending fingers or segments. The protrusion may include an enlarged end that snaps fits into the undercut portion of the recess at the center of the sealing element. This snap-fit ​​connection allows relative rotation between the sealing element and the cap body, whereby there is generally no relative rotation between the annular sealing element and the container neck when the screw cap is screwed on or off.

[0019] The stop may, for example, be integrally formed with the expandable plug seal assembly as an annular flange extending radially from the upper portion of the backing. The backing and sealing element may include through-grooves extending radially in the sealing element and axially in the annular sealing element; thereby allowing easier radial expansion of the plug seal by widening the groove to absorb most of the resulting strain. The axially extending through-grooves may be used to define multiple independent axially extending sections of the backing. These grooves may extend into the annular flange forming the stop. Additionally or alternatively, these grooves may be combined with, extend into, or become part of the radial through-grooves in the sealing element. A finish may at least cover the outer circumference of the annular sealing element and may sealably cover the through-grooves therein, such that when the plug seal expands, the finish sealably presses against the inner surface of the container neck around its entire circumference to achieve an hermetically airtight seal of the container. The finish can also cover the lower surface of the annular flange forming the stop, so as to provide an airtight seal against the edge of the container neck when the cap body is screwed onto the container neck. The bottom surface of the sealing element can have a cover made of a softer and more flexible material to seal the groove therein. This cover can be continuous with the finish to prevent contact between the packaging material and other parts of the screw cap. Therefore, PCR material can be used to make these other parts while still allowing the screw cap to be used in food-grade or similar hygienic applications. The backing and finish can be formed by insert molding (two-material injection molding). The sealing element can include a dome shape that becomes flatter and radially expands when the stop engages the container neck, the cap body is screwed onto the container neck, and the end walls of the cap body press down on the central portion of the sealing element.

[0020] The expandable plug sealing subassembly may include a through-hole onto which a gas-permeable but liquid-impermeable diaphragm is fixed to provide a gas venting path. For example, the through-hole may be formed in a sealing activating element. The through-hole may also be formed in a recess at the center of the sealing activating element. This recess may be part of a snap-fit ​​connection as described above. The stop and / or the inner surface of the cap body end wall may be provided with a groove or protrusion that, when the screw cap is fully tightened, spacees the stop from the inner surface of the cap body end wall, thereby providing a gas flow path that connects the space between the sealing activating element and the cap body end wall to the atmosphere via an internal thread within the cap body. Attached Figure Description

[0021] The invention and some of its additional optional features and advantages are described below with reference to the illustrative embodiments shown in the accompanying drawings, in which:

[0022] Figure 1 This is an exploded top perspective view illustrating the screw cap body, the expandable plug assembly, and one side of the corresponding container neck of the present invention.

[0023] Figure 2 yes Figure 1 An exploded perspective view of the components shown;

[0024] Figure 3 Corresponding to Figure 1 However, these components are shown in partial cross-section;

[0025] Figure 4 and Figure 5 It is a partial sectional perspective view from one side, showing the screw cap body and expandable plug assembly snapped together, and the resulting screw cap being partially screwed onto the neck of the container.

[0026] Figure 6 This is a partial sectional perspective view from one side, showing components such as... Figure 4 and Figure 5 Assembled as described above;

[0027] Figure 7 It is a side view similar to the expandable plug body sub-assembly shown in the previous figures, and

[0028] Figure 8 It is a modified diametrical cross-sectional view through the expandable plug body plug assembly, which can be used as a component in the screw cap embodying the present invention. Detailed Implementation

[0029] First turn Figure 1The illustrative screw cap includes a cap body 10, within which an expandable plug sealing sub-assembly 24 is rotatably housed, as further explained below. Figure 1 A complementary container neck 26 is also shown, which can be closed and sealed by the cap body 10 and the attached plug sealing sub-assembly 24. The cap body 10 includes a disc-shaped end wall 12 and generally cylindrical side walls 14 hanging from the periphery of the end wall 12. A radially outwardly extending protective flange 16 is provided at the bottom of the side wall 14 opposite the end wall 12, and an tamper-evident ring 18 is brittlely attached below the protective flange 16 in a known manner. The screw cap body 10 and the tamper-evident ring 18 can be manufactured as a single component, for example, by injection molding from a suitable plastic material such as PE or PCR plastic. Figure 2 and Figure 3 As best shown, the sidewall 14 of the cap body has an internal screw thread 20. A protrusion 22, formed by a pair of axially extending fingers or segments 28, hangs centrally from the inner surface of the end wall 12 of the cap body. The protrusion 22 forms part of a snap-fit ​​connection, by which the plug sealing sub-assembly 24 can be rotatably held in the cap body 10 even when the screw cap is not screwed onto the container neck 26. Each axially extending finger or segment 28 has an enlarged end 28a.

[0030] Figures 3-6 The annular sealing element 30 of the plug seal assembly 24 is shown. More specifically, the cross-sectional views of these figures show the structure of the annular sealing element 30, including its backing 34 and its facing 44. The backing 34 is formed of a relatively rigid but resilient material, such as a suitable PCR plastic material, which is resilient enough to return to its original shape when external stress is removed. The facing 44 is formed of a softer, more compliant material, such as a suitable elastomer (such as NBR, EPDM, neoprene, or silicone elastomers). For example, the material used to form the facing 44 can be selected to be compatible with the contents of the container (e.g., not reacting with them).

[0031] When the screw caps 10 and 24 are screwed on, the stop for supporting the annular sealing element 30 within the container neck 26 may include an annular flange 32 that projects radially outward from or near the upper end of the backing 34.

[0032] The sealing element 38 illustrated in the accompanying drawings has a shallow, generally truncated conical configuration, but this is not essential to the present invention. Other (generally generally dome-shaped) configurations are also possible, which allow the sealing element to expand radially between its central and peripheral portions due to axial compression when the cap body 10 is screwed onto the container neck 26.

[0033] In use, the apex or center portion 39 of the sealing element 38 points towards the center of the end wall 12 of the cap body. A recess 43 with a circular cross-section is provided, having an entrance at the apex and a depth extending axially downward. The recess 43 has an inwardly extending peripheral retaining lip 50 forming an undercut or recessed portion at the bottom of the recess, into which the enlarged ends 28a of the axially extending fingers or segments 28 can snap into. Thus, the plug sealing sub-assembly 24 is rotatably held in the cap body 10. The apex or center portion 39 of the sealing element, the recess 43, and the protrusion 22 also form a rotational thrust bearing, thereby allowing the cap body 10 to rotate relative to the plug sealing sub-assembly 24 when the cap is screwed on or off the container neck 26, and the plug sealing sub-assembly 24 to remain stationary within the container neck 26. However, the described snap-fit ​​interconnections 22, 43 between the cap body 10 and the plug sealing sub-assembly 24 are not essential to the present invention. The apex 39 of the sealing energizing element 38 can simply abut directly or indirectly against the inner surface of the end wall 12 of the cap body to form a rotary thrust bearing. As those skilled in the art will know, other retaining mechanisms / rotary thrust bearings are also possible between the cap body 10 and the plug sealing sub-assembly 24.

[0034] The peripheral portion 36 of the elastically deformable sealing element 38 is connected to the backing 34 of the annular sealing element 30 at or below the level of the stop (radially protruding annular flange) 32. The backing 34 extends below this connection and is divided by a plurality of axially extending through grooves distributed circumferentially into radially distributed segments 42 corresponding to a plurality of axially extending segments. Figure 4 ).like Figure 3 and Figure 6 As illustrated, the depth of the portion of the backing 34 extending below the connection or sealing element periphery 39 is approximately twice the depth of the portion of the backing extending between the connections to the horizontal plane of the flange. However, other configurations also effectively provide the beneficial sealing effect of the present invention. For example, the connection or sealing element periphery 36 may be located at the horizontal plane of the flange 32, whereby the entire backing 34 extends below the connection 36; or the connection 36 may be located at a horizontal plane approximately three-quarters of the way down from the flange 32 along the backing 34; or the connection 36 may be located at a horizontal plane at any position within this range.

[0035] The edge of the groove 40 and the corresponding edge of the axially extending segment 42 are in Figure 4 The area shown is indicated by a dashed line; in this partial sectional view, it is still covered by finish 44. Figure 3In the diagram, the material passing through the backing 34 and the sealing energizing element 38 is shown in cross-section on the left side of the plug seal subassembly 24. However, a groove 40 passing through the backing 34 is shown in cross-section on the right side. Typically, this groove can be filled with finishing material 44. (The groove 40 widens during the desired deformation of the annular sealing element 30, thereby allowing separation from any filler material, where compressive interference of the material is not an issue). For clarity of illustration, Figure 3 The right-hand side shows that this groove 40 is empty. To facilitate radial expansion of the truncated conical or dome-shaped sealing element 38 under axial compression, it may be provided with multiple radially distributed, radially extending through grooves 40a. The grooves 40 in the backing 34 may extend into the sealing element 38, for example, to engage with, extend into, or become part of the radial through grooves 40a, as... Figure 3 As shown in the diagram. The upper end 40b of the groove 40a terminates near the apex or center portion 39 of the sealing energizing element, for example, at or near the recess 43. The groove 40 in the backing 34 may also have an upwardly extending through continuation 40c, which may terminate in a radially projecting annular flange (stop) 32 to leave a series of relatively small bridging elements 32a. Figure 3 This increases the out-of-plane flexibility of the flange 32, allowing it to more easily adapt to corresponding irregularities in the upper end surface of the container neck 26. The grooves 40c and 40a also increase the radial flexibility of the annular sealing element 30, allowing it to better adapt to the out-of-roundness of the container neck bore. The trim 44 can extend radially outward to the lower surface of the annular flange 32 to aid in forming a seal with the upper end surface of the container neck 26. The backing 34, together with the stop flange 32 and the sealing energizing element 38, can be formed as a one-piece component, for example, by injection molding.

[0036] In its relaxed state, the diameter of the annular sealing element 30 tapers slightly in the axial direction away from the flange 32. This allows the expandable plug sealing sub-assembly 24 to be guided and more easily pushed into the bore of the container neck 26 when the cap body 10 is screwed into place on the container neck. Therefore, the flange (stop) 32 ultimately rests on the upper end surface of the container neck 26. When the plug sealing sub-assembly 24 in its relaxed state is first secured to / fully inserted into the cap body 10, a gap 52 exists between the upper surface of the flange 32 and the adjacent portion of the cap body end wall 12. Figure 4After the flange (stop) 32 rests on the upper end surface of the container neck 26, continued screwing of the cap body 10 causes the gap 52 to decrease and the dome-shaped sealing element 38 to become flatter. This flattening causes the sealing element 38 to expand radially, and the presence of the radial through groove 40a assists in this flattening and radial expansion. The radial expansion of the sealing element 38 forces the adjacent upper portion of the annular sealing element 30 to engage more tightly within the bore of the container neck 26. Due to its connection to its periphery 36, the flattening of the sealing element 38 also causes the axially extending segment 42 of the backing 34 to pivot upward and outward. The ungrooved portion of the flange (stop) 32 and / or the adjacent edge of the container neck can assist this pivoting movement by acting as a fulcrum. Thus, as the cap body continues to be screwed, the taper of the annular sealing element 30 decreases. Therefore, the annular sealing element 30 presses against the bore of the container neck 26 with a more uniform pressure across its axial range (and uniformly around its circumference). Further expansion of the annular sealing element 30 is essentially entirely limited by the container neck. Further tightening of the cap body 10 beyond this point (e.g., to completely eliminate gap 52) primarily results in further bending of section 42 and the sealing energizing element 38, and thus additional locking bending stress within section 42 and the sealing energizing element 38. These locking stresses (pre-stresses) can be used to maintain uniform sealing pressure between the annular sealing element 30 and the bore of the container neck 26, even in the presence of creep in the finish 44 and / or the container neck 26. Therefore, a low and predictable tightening torque (to completely eliminate gap 52 and cause the tamper-evident ring 18 to engage the one-way teeth 54 on the container neck 26) is sufficient. Figure 5 This results in a reliable and durable seal, enabling it to accommodate a wide range of variations in the size and profile of the container neck bore. With the elimination of gap 52, when the final tightening torque is applied to the screw cap body 10, the finish 44 on the underside of flange 32 is forced into a tighter sealing engagement with the corresponding edge surface of the container neck 26.

[0037] A cover 44a made of a softer and more compliant material (such as, but not limited to, the material of finish 44) can be applied to the bottom surface of the sealing element 38 to seal the groove 40a without significantly affecting the ability of the sealing element 38 to expand radially under axial compression. This cover 44a can be continuous with the finish 44 and thus also cover the radially inner surface of the axially extending segment 42, the groove 40a, and the lower edge of the backing 34. For example, the finish 44 and the cover 44a can be insert-molded (two-ply injection molded) onto the underside of the flange 32, both sides of the backing 34, and the bottom surface of the sealing element 38 in a single operation. Therefore, the finish 44 and the cover 44a can seal not only the grooves 40 and 40a, but also the groove 40c (if present). The finish 44 and the cover 44a may also provide a continuous, uninterrupted layer that seals the entire circumference of the bore in the neck 26 of the container and spans across this bore to isolate the contents of the container from the other components of the screw cap. Therefore, these other components can be made of PCR plastic, eliminating the risk of contamination of the contents of the container even when the screw cap is used in pharmaceutical, food, or other similar applications with high hygiene requirements.

[0038] Figure 2 and Figure 6 The plug seal 24 shown is slightly different Figure 3 The version shown is characterized by, in Figure 2 and Figure 6 In the middle, the central region of the sealing and energizing element 38 (e.g., the bottom wall 43a of the recess 43 enclosure) Figure 6 (If present) not covered by covering 44a. This exposed portion 43a is provided with several through holes 62. Three such holes can be used, but other numbers are also suitable, including one. Figure 6 In the middle, only two of the three orifices 62 are visible; the third orifice is cut off. A microporous, gas-permeable but liquid-impermeable diaphragm 64 is hermetically fixed to the exposed central region 43a of the sealing energy element 38 at its periphery in order to cover and surround the orifices 62.

[0039] For illustrative purposes and not for any technical needs, Figure 2 and Figure 6In this diagram, the microporous diaphragm 64 is shown as partially transparent, allowing the orifice 62 to be seen through it. For "discharge" applications, the diaphragm 64 can be secured to the exposed area of ​​the sealing element 38 directly surrounded by the cover 44a (e.g., to the lower surface of the bottom wall 43a of the cavity 43 enclosure, if present). For "inflow" applications (not shown), the diaphragm can be secured to the opposite side of the sealing element 38, for example, to the upper surface of the bottom wall 43a of the cavity 43 enclosure, if present. In each case, the sealing element 38 is thus supported and protected from rupture of the diaphragm 64 due to overpressure.

[0040] Additional gas venting channels may be provided in the form of shallow recesses 66 (or other channels of suitable shape), extending across the radial width of the flange / stop 32 on the side facing away from the container. Thus, these channels open from the space between the plug seal 24 and the end wall 12 of the cap body to the annular region occupied by the container neck 26. Therefore, they provide a gas venting path between the interior of the container and the atmosphere via the internal threads 20 of the screw cap body 10. Additionally or alternatively, to complete the gas venting path, similar gas venting channels, conduits, spacer ridges, or the like may be provided in or on the inner surface of the protrusion 22, the recess 43, the apex 39 of the sealing activating element 38, and / or the inner surface of the end wall 12 of the cap body. Optionally, such as Figure 3 As shown above, in non-gas emission applications, the orifice 62 may be present in the sealing element 38, but not covered and sealed by, for example, a cover 44a. In this way, the same molding tool can be used to form the sealing element 38 in both the gas emission and non-gas emission versions of the screw cap.

[0041] refer to Figure 7 The radially outer surface of the annular sealing element 30 tapers substantially constantly from the stop (radially projecting annular flange) 32 until a rounded bottom edge is formed, at which the trim 44 and the cover 44a surround the distal tip of the segment 42. This profile allows the plug sealing assembly 30 to be easily guided into the bore of the container neck when the screw cap is screwed onto the container neck. Other profiles are also possible. Figure 8 Another non-limiting example is shown, wherein the lower portion of the radially outer surface of the annular sealing element tapers, and the upper portion of this surface (adjacent to the stop / flange 32 and adjacent to the connecting portion 36) is generally cylindrical. When the cap is screwed onto the container neck, the expansion of the plug sealing assembly 24 may result in generally uniform pressure on this cylindrical portion of the finish 44 as it is pressed against the bore of the container neck.

[0042] Already used as Figure 7 and Figure 8The core sealing subassembly 24 shown was tested, and in each case, it was fitted to a 60mm screw cap (the applicant's modified 60mm "Plasticap" (RTM) cap). The test cap was screwed onto the neck of a simulated fuel tank with a torque of 5 Nm. The neck of the simulated fuel tank was internally machined to simulate a 3mm bore ellipticity—that is, the difference between the large and small diameters of the bore is 3mm, and the large and small diameters are perpendicular to each other. No leakage was observed when the cap / neck was immersed in a water tank and pressurized to 318 mbar with compressed air. In another test, the cap was screwed onto a standard sample fuel tank with a torque of 5 Nm. The fuel tank was filled with water at room temperature and kept inverted for a 24-hour cycle. Again, no leakage was observed. In a third test, the core sealing subassembly 24 was fitted with a 60mm screw cap (the applicant's modified 60mm "Plasticap" (RTM) cap) according to the specifications. Figure 7 and Figure 8 The test caps (also with a closing torque of 5 Nm) were applied to two ordinary empty fuel cans until significant expansion (“inflation”) occurred. The air pressures required to perform this operation were recorded (5.5 bar and 6.0 bar, respectively). The fuel cans were then immersed in a water tank. Again, no leakage was observed. Therefore, the test caps performed well even with substantial deformation of the container neck bore.

Claims

1. A screw cap, comprising: A cover body, the cover body including an end wall and an internally threaded annular side wall hanging from the end wall; An annular sealing element, the annular sealing element being concentrically disposed within and spaced apart from the annular sidewall, such that when the screw cap is screwed onto the container neck, the annular sealing element can be received within the externally threaded container neck; The annular sealing element includes a stop portion that can engage with the container neck to support the annular sealing element within the container neck when the screw cap is screwed onto the container neck. An elastically deformable sealing element, the elastically deformable sealing element comprising a central portion supported against the end wall of the cover body and a peripheral portion connected to the annular sealing element; The sealing element is constructed and operably arranged within the cap body such that when the cap body is screwed onto the container neck, axial compression of the sealing element between the central portion and the peripheral portion causes radial expansion of the sealing element at the peripheral portion, thereby causing the annular sealing element to expand radially toward the inner surface of the container neck. The annular sealing element includes a backing made of a relatively rigid but elastic material and a radially outer surface made of a relatively more flexible material, wherein the backing extends in a direction away from the end wall of the cover body below the horizontal plane of the stop; Its features are: The peripheral portion of the sealing and energizing element is connected to the backing at or below the stop at a horizontal plane, and the backing below this horizontal plane includes a plurality of independent axially extending segments.

2. The screw cap according to claim 1, wherein, The sealing energizing element and the annular sealing element include portions of an expandable plug sealing subassembly that can be positioned within the screw cap.

3. The screw cap according to claim 2, wherein, The plug sealing sub-assembly and the cap body are connected by a snap-fit ​​connection, which allows the plug sealing sub-assembly to remain in the cap body even when the screw cap is not screwed onto the neck of the container.

4. The screw cap according to claim 3, wherein, The snap-fit ​​connection includes a recess at the center of the sealing element, and a protrusion extending from the end wall of the cover body is snap-fitted into the recess.

5. The screw cap according to claim 4, wherein, The protrusion includes multiple axially extending finger-like portions or segments.

6. The screw cap according to claim 4 or 5, wherein, The protrusion includes an enlarged end that snaps into the undercut portion of a recess at the center of the sealing element.

7. The screw cap according to any one of claims 3-5, wherein, The snap-fit ​​connection allows relative rotation between the sealing element and the cap body, so that when the screw cap is screwed on or off, there is generally no relative rotation between the annular sealing element and the container neck.

8. The screw cap according to any one of claims 2-5, wherein, The stop portion is integrally formed with the expandable plug sealing sub-assembly as an annular flange extending radially from the upper portion of the backing.

9. The screw cap according to any one of claims 1-5, wherein, The backing and the sealing element include a through groove extending radially in the sealing element and axially in the annular sealing element, wherein the axially extending through groove is used to define a plurality of independent axially extending segments of the backing.

10. The screw cap according to claim 9, wherein, The axially extending through groove extends into the annular flange that forms the stop portion.

11. The screw cap according to claim 9, wherein, The axially extending through groove is combined with, extends into, or becomes part of the radial through groove in the sealing and energizing element.

12. The screw cap according to claim 9, wherein, The bottom surface of the sealing and energizing element has a cover made of a softer, more flexible material to seal the groove therein.

13. The screw cap according to claim 12, wherein, The covering is continuous with the finish.

14. The screw cap according to any one of claims 1-5, wherein, The sealing element includes a dome shape that becomes flatter and radially expands when the stop engages the container neck, the cap body is screwed onto the container neck, and the end wall of the cap body is pressed down onto the central portion of the sealing element.

15. The screw cap according to claim 2, wherein, The expandable plug sealing sub-assembly includes a through-hole onto which a gas-permeable but liquid-impermeable diaphragm is fixed to provide a gas venting path.

16. The screw cap according to claim 15, wherein, The through-hole is formed in the sealing and energizing element.

17. The screw cap according to claim 16, wherein, The through-hole is formed in a recess at the center of the sealing and energizing element.

18. The screw cap according to claim 17, wherein, The plug sealing sub-assembly and the cap body are connected by a snap-fit ​​connection, which allows the plug sealing sub-assembly to remain in the cap body even when the screw cap is not screwed onto the neck of the container.

19. The screw cap according to claim 18, wherein, The snap-fit ​​connection includes a recess at the center of the sealing element, and a protrusion extending from the end wall of the cover body is snap-fitted into the recess.

20. The screw cap according to claim 19, wherein, The protrusion includes multiple axially extending finger-like portions or segments.

21. The screw cap according to claim 20, wherein, The protrusion includes an enlarged end that snaps into the undercut portion of the recess at the center of the sealing element.

22. The screw cap according to any one of claims 15-21, wherein, The stop portion and / or the inner surface of the end wall of the cap body are provided with a groove or protrusion. When the screw cap is fully tightened, the groove or protrusion separates the stop portion from the inner surface of the end wall of the cap body.

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