GB1602746A - Closure device for containers - Google Patents

Description

(54) CLOSURE DEVICE FOR CONTAINERS (71) We, DANIEL MONTGOMERY & SON LIMrrED, a British Company, of Old Mill Park Estate, Kirkintilloch, Glasgow, Scotland do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to a closure device for containers and particularly to a screw cap for screwing over the neck of a container provided with a screw-threaded neck. One such type of container to which the invention is applicable is a bottle.

It has already been proposed to provide a cap for a screw-threaded bottle neck in which the inner end face of the cap is provided with a flexible annular protuberance protruding from the face, said protuberance having a side face which is at an oblique angle to the axis of the cap and is engageable with the rim of a screw-threaded neck to which the closure is applicable so that as the cap is screwed cn to the neck the side face of the protuberance comes against the end of the neck and is moved radially so that the protuberance is splayed outwardly or inwardly and is ultimately squashed flat between the end of the neck and the inner end face of the cap, the deflecting force between the end of the screw-threaded neck and the annular protuberance providing a sealing effect between the end of the neck and the cap.

In this construction adequate sealing is dependent on ahigh degree of fmish and regularity of the end of the neck to which the cap is fitted because there can be little resiliency in the material of which the cap is made otherwise the cap would deform when screwed tightly on to the neck. This low degree of resiliency necessarily reduces the capacity of the annular protuberance to compensate for irregularities in the end of the neck to which the cap is fitted.

More effective sealing against an irregular neck would be obtainable by greater resiliency in the sealing contact between the cap and the end of the neck to which the cap is applied.

According to the invention a cap for a con tainer of the type having a screw-threaded neck presenting an end face in the form of an annulas, the cap being arranged to fit over the neck, is formed with a flexible annular protuberance protruding from the inner end face of the cap and diverging towards the open end of the cap said annular protuberance being thicker at the base than at the tip and having at least one side surface of non-cylindrical form and a rigid annular ridge having an outwardly splayed upper surface, i.e. having an altitude above the end face of the cap at the maximum diameter of the ridge greater than the altitude at its minimum diameter said ridge being formed as a fillet located at the periphery of the inner end face of the cap, there being an annular groove between the base of the annular protuberance and the inner periphery of the annular ridge, the width of the groove being less than the width of the end face of the neck and having a mean diameter substantially the same as the mean diameter of the end face, the height of the protuberance being greater numerically than the width of the groove and the diameter of the inner periphery of the ridge being less than the outer diameter of the neck.

A practical embodiment of the invention is illustrated in the accompanying drawings in which Figure 1 shows in section the upper end of the externally screw-threaded neck of a bottle with a cap fitted and Figures 2 and 3 are sections to a larger scale of the portion ringed in Figure 1 showing the cap approaching the sealing position and the cap in the sealing position respectively.

In the drawings 1 denotes a cap and 2 denotes a bottle neck formed with an external screw thread 3. 4 denotes the inner end face of the cap incorporating a flexible annular proturbance 5 protruding from the inner end face 4 of the cap 1. The protruberance 5 is outwardly divergent so that it presents a side surface 6 of a non-cylindrical form and is thicker and thus stiffer at the base than it is at the tip. The inner end face 4 of the cap is formed with an annular ridge 7 coaxial with the cap and of greater diameter than the protuberance so that it surrounds the protuberance 5. The ridge is formed as a fillet located at the periphery of the end face 4.An annular groove 8 lies between the outer periphery of the base of the protuberance 5 and the inner periphery of the ridge 7 The width of the groove 8 is numerically less than the height of the annular protuberance as measured from the base to the tip of the protuberance and is also less then the width of the end face of the bottle neck 2. The mean diameter of the groove 8 is substantially equal to the mean diameter of the face of the bottle neck 2.

The top of the annular ridge 7 is outwardly splayed i.e. the altitude of the ridge above the end face 4 of the cap at the maximum diameter of the ridge is greater than the altitude of the ridge at its minimum diameter.

The drawings illustrate a cap fitted to a bottle neck formed with an external screw thread. It is to be understood that a cap according to the invention can be made to fit a bottle with an internally screw-threaded neck.

In such a case the cap is formed with an externally screw-threaded spigot projecting from the inner end face of the cap and engageable with the screw thread in the bottle neck, the annular protuberance surrounding the spigot.

In practice, when the cap 1 is applied to a screw-threaded bottle neck such as 2 and is screwed on to the bottle neck the tip of the annular protuberance 5 comes against the end o of the neck 2 (see Figure 2) and as the cap is moved further on to the neck the non-cylindrical annular protuberance 5 is deflected by wedge action so that the tip moves radially across the end of the neck and is ultimately brought into contact with the top of the annular ridge 7 (see Figure 3). Continued tightening of the cap on the neck nips the tip of the annular protuberance between the end of the neck and the ridge. The stiffer thicker base of the annular protuberance resists the deforming action and causes the protuberance to lie across the end of the bottle neck 2.Air trapped in the annular pocket thus formed by the annular groove 8 and the annular protuberance acting like a lid over the groove 8 is compressed as the cap is tightened on to the bottle neck. The effect is now that of a resilient gas-filled ring pressed against the end of the cap, the trapped air under pressure providing a resilient force pressing the portion of annular protuberance unsupported between the base of the protuberance 5 and the ridge 7 into close sealing engagement with the end of the neck 2 thus filling any irregularity in the end of the neck so that a perfect seal is provided against any neck formed to normal standards of manufacture.

The outward splaying of the top surface of the annular ridge contributes to the compression of the air in the annular space between the base of the annular protuberance and the annular ridge because in the screwing of the cap on to the neck the tip of the annular protuberance 5 comes first against the splayed surface of the annular ridge 7 and initially seals the annular space. Continued screwing of the cap on to the neck causes the flattened annular protuberance to move back towards the inner end face 4 of the cap, i.e. towards the bottom of the groove 8, thereby reducing the volume of the annular space without allowing any of the air trapped therein to escape so that the pressure of the trapped air is increased. This augments the sealing action.

WHAT WE CLAIM IS: 1. A cap for a container of the type having a screw-threaded neck presenting an end face in the form of an annulus, the cap being arranged to fit over the neck, formed with a flexible annular protuberance protruding from the inner end face of the cap and diverging towards the open end of the cap said annular protuberance being thicker at the base than at the tip and having at least one side surface of non-cylindrical form and a rigid annular ridge having an outwardly splayed upper surface, i.e. having an altitude above the end face of the cap at the maximum diameter of the ridge greater than the altitude at its minimum diameter said ridge being formed as a fillet located at the periphery of the inner end face of the cap, there being an annular groove between the base of the annular protuberance and the inner periphery of the annular ridge, the width of the groove being less than the widgh of the end face of the neck and having a mean diameter substantially the same as the mean diameter of the end face, the height of the protuberance being greater num- erically than the width of the groove and the diameter of the inner periphery of the ridge being less than the outer diameter of the neck.

2. A cap for a container of the type having a screw-threaded neck as claimed in Claim 1 and substantially as described with reference to the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (2)

**WARNING** start of CLMS field may overlap end of DESC **. the height of the annular protuberance as measured from the base to the tip of the protuberance and is also less then the width of the end face of the bottle neck 2. The mean diameter of the groove 8 is substantially equal to the mean diameter of the face of the bottle neck 2. The top of the annular ridge 7 is outwardly splayed i.e. the altitude of the ridge above the end face 4 of the cap at the maximum diameter of the ridge is greater than the altitude of the ridge at its minimum diameter. The drawings illustrate a cap fitted to a bottle neck formed with an external screw thread. It is to be understood that a cap according to the invention can be made to fit a bottle with an internally screw-threaded neck. In such a case the cap is formed with an externally screw-threaded spigot projecting from the inner end face of the cap and engageable with the screw thread in the bottle neck, the annular protuberance surrounding the spigot. In practice, when the cap 1 is applied to a screw-threaded bottle neck such as 2 and is screwed on to the bottle neck the tip of the annular protuberance 5 comes against the end o of the neck 2 (see Figure 2) and as the cap is moved further on to the neck the non-cylindrical annular protuberance 5 is deflected by wedge action so that the tip moves radially across the end of the neck and is ultimately brought into contact with the top of the annular ridge 7 (see Figure 3). Continued tightening of the cap on the neck nips the tip of the annular protuberance between the end of the neck and the ridge. The stiffer thicker base of the annular protuberance resists the deforming action and causes the protuberance to lie across the end of the bottle neck 2.Air trapped in the annular pocket thus formed by the annular groove 8 and the annular protuberance acting like a lid over the groove 8 is compressed as the cap is tightened on to the bottle neck. The effect is now that of a resilient gas-filled ring pressed against the end of the cap, the trapped air under pressure providing a resilient force pressing the portion of annular protuberance unsupported between the base of the protuberance 5 and the ridge 7 into close sealing engagement with the end of the neck 2 thus filling any irregularity in the end of the neck so that a perfect seal is provided against any neck formed to normal standards of manufacture. The outward splaying of the top surface of the annular ridge contributes to the compression of the air in the annular space between the base of the annular protuberance and the annular ridge because in the screwing of the cap on to the neck the tip of the annular protuberance 5 comes first against the splayed surface of the annular ridge 7 and initially seals the annular space. Continued screwing of the cap on to the neck causes the flattened annular protuberance to move back towards the inner end face 4 of the cap, i.e. towards the bottom of the groove 8, thereby reducing the volume of the annular space without allowing any of the air trapped therein to escape so that the pressure of the trapped air is increased. This augments the sealing action. WHAT WE CLAIM IS:

1. A cap for a container of the type having a screw-threaded neck presenting an end face in the form of an annulus, the cap being arranged to fit over the neck, formed with a flexible annular protuberance protruding from the inner end face of the cap and diverging towards the open end of the cap said annular protuberance being thicker at the base than at the tip and having at least one side surface of non-cylindrical form and a rigid annular ridge having an outwardly splayed upper surface, i.e. having an altitude above the end face of the cap at the maximum diameter of the ridge greater than the altitude at its minimum diameter said ridge being formed as a fillet located at the periphery of the inner end face of the cap, there being an annular groove between the base of the annular protuberance and the inner periphery of the annular ridge, the width of the groove being less than the widgh of the end face of the neck and having a mean diameter substantially the same as the mean diameter of the end face, the height of the protuberance being greater num- erically than the width of the groove and the diameter of the inner periphery of the ridge being less than the outer diameter of the neck.

2. A cap for a container of the type having a screw-threaded neck as claimed in Claim 1 and substantially as described with reference to the accompanying drawings.