Safety cap for pressurized containers

Abstract: A safety cap for pressurized containers includes a closure member (2) of the aperture (3) of the container (4) and a grip member (5) having a connecting means (6) with the closure member for removing the closure member from the aperture only when the pressure inside the container is at a preset value. A safety device (7) is adapted to slide inside the closure member (2) from a first position to a second position and vice versa, for activating and disactivating the connecting means as the pressure varies, and seal means (8) between the closure member and at least a first and a second region of the safety device.

Description: The present invention relates to a safety cap for pressurized containers. Several types of safety caps for pressurized containers are known. Generally, conventional safety caps comprise a closure member of the aperture of the container and a grip member which, depending on the pressure level inside the container, can rotate freely with respect of the closure member in order to prevent the removal of the cap when the pressure is to high. On the contrary, when the pressure inside the container is low, or at any rate below a dangerous value, the grip member is rigidly associated with the closure member by connecting means adapted to allow the user to remove the cap. Normally, the connecting means between the grip member and the closure member of the safety cap are activated by the motion of a slider inside the cap, by the pressure generated inside the container. Namely, when the pressure increases, the slider is moved upwardly, in contrast with elastic means, thereby disactivating the connecting means and making the grip member free to rotate with respect of the closure member. On the contrary, when the pressure decreases to an acceptable level which is no longer dangerous, the slider is lowered by the elastic means thereby activating the connecting means which allows the rotation of the closure, member, through the rotation of the grip member, for removing the closure member from the aperture of the container. In conventional safety caps, the seal between the slider and the closure member is usually provided by an O-ring. It is apparent that, after a while, the O-ring will not guarantee a perfect seal between the surfaces of the slider and of the closure member allowing a more or less great quantity of vapour to escape. This inconvenience seems to be of no consequence but actually completely impairs the correct operation of the safety cap. In fact, the displacement of the slider by the elastic means, such as a spring, is modified by the pressure inside the container which is in turn modified by the leaks between the slider and the closure member. In other words, the pressure inside the container may not reach a value high enough to allow the slider to move upwardly against the elastic means preventing a secure disengagement between the grip member and the closure member which may be removed from the container with fatal consequences. Furthermore, when the vapour leaks between the slider and the closure member surfaces, it tends to condense and leave calcareous deposits on the same surfaces, on the 0-ring and on the connecting means which eventually impair the correct operation of the cap. EP-A-0 400 514 discloses a safety closure for pressurized containers that has not a seal with an enlarged edge on a first face and a flexible rim on a second face in order to acts along two directions perpendicular and parallel with respect to the sliding direction of the safety device. The aim of the present invention is to eliminate the above described inconveniences of the prior art. Within this aim, an object of the invention is provide a safety cap for pressurized containers having seal means between the slider and the closure member adapted to prevent any leak between their surfaces even after a long use. A further object of the invention is to provide a safety cap which maintains constant operation settings as established at manufacture. Still a further object of the invention is to provide a cap for pressurized containers wherein the means connecting the closure member with the grip member remains free from calcareous deposits and therefore do not deteriorate or break. Still a further object of the invention is to provide a cap having a valid operation with an extremely simple structure and therefore with a low cost. The above aim, as well as these and other objects that will be more apparent hereinafter, are achieved by a safety cap for pressurized containers as claimed in claim 1. Further characteristics and advantages of the invention will be more apparent by the following description of an embodiment of the invention, illustrated, by way of example in the enclosed drawings wherein: FIG. 1 is a side elevated cross section view of the safety cap according to the invention, wherein the grip member and the closure member are connected together; FIG. 2 is a view of the cap according to FIG. 1 wherein the grip member and the closure member are disconnected, according to the invention. With reference to the above figures, the safety cap according to the invention, generally designated by the reference numeral 1, comprises a closure member 2 of the aperture 3 of a pressurized container 4. Closure member 2 is contained inside a grip member 5 and is connected or disconnected thereto by a connecting means 6 so that the closure member may be removed from aperture 3 only when the pressure inside container 4 is at a selected value. Inside closure member 2, a safety device 7 can slide between a first position and a second position for activating or disactivating connecting means 6, as the pressure varies inside container 4. At rest, when there is no pressure inside the container, safety device 7 is arranged in a second position, as shown in FIG. 1, while when there is pressure inside container 4, the safety device moves to a first position, as shown in FIG. 2, wherein the grip member can freely rotate above closure member 2. Advantageously, the safety cap has a seal means, formed by a seal or gasket 8, between closure member 2 and at least a first and a second regions of safety device 7. In particular, seal 8 varies the seal rate according to the variation of pressure inside container 4. Seal 8 has a circular main body which comprises an enlarged edge 9, on a first face, and a flexible rim 10, on a second face. Flexible rim 10 acts on the first region of the safety device defined by an external wall 11 of the safety device, while enlarged edge 9 is arranged in an annular seat 12 of closure member 2. The second seal region of the closure member, with safety device 7, is defined by an annular bracket 14 engaging the second face of seal 8 when the closure member is in the first position (FIG. 2), wherein grip member 5 is freely rotatable with respect of closure member 2. Safety device 7 also has an annular seat 15 comprised between external wall 11 and bracket 14. Edge 10 is arranged within annular seat 15 when the closure member is in the first position (FIG. 1) and the grip member is rigidly associated with the closure member whereby the rotation of the grip member allows the closure member to be removed from aperture 3 of container 4. Seal 8 acts in the first region defined by wall 11 along a first direction which is substantially perpendicular to the sliding direction of the safety device inside closure member 2, while in the second region, defined by bracket 14 and by the second face of seal 8, the seal is provided along a direction which is substantially parallel to the sliding direction of the safety device. This particular configuration allows seal 8 to act sequentially in the first and second regions in order to prevent any leak between the closure member and safety device 7, even after a long use. Connecting means 6 comprises a bar 20 which is movable inside a seat 21, defined in the grip member 5, and is biased by elastic means, namely a preset spring 22. Bar 20 moved by safety device 7 raising or lowering from the first position to the second position, and vice versa, in order to engage or disengage teeth 23 provided on the closure means. The operation of the safety cap for pressurized containers, according to the invention, is apparent from the above description. Namely, when there is no pressure in container 4, safety, device 7 is in the second position, shown in FIG. 1, and is lowered by the action of spring 22. In this situation, grip member 5 is rigidly associated with, and may rotate therewith, closure member 2 because bar 20 is at the same time engaged with seat 21 and teeth 23 of the two elements; edge 10 of seal 8 provides for the seal on wall 11 of the safety device. When the pressure inside container 4 rises, flexible edge 10 will increase the seal on wall 11 proportionally to the increase of pressure. As the pressure increases, safety device 7 starts to rise compressing spring 22 and increasing the seal on wall 11. When the pressure has reached a selected value, safety device 7 will be in the first position (as illustrated in FIG. 2) wherein bar 20 is completely disengaged from teeth 23 and the grip member is free to rotate with respect to closure member 2. In this position, a second seal is provided, between the closure member and safety device 7, by bracket 14 contacting the second face of seal 8. In this situation, when the pressure is considered to be dangerous for the user, it is impossible to remove closure member 2 from aperture 3 of container 4 and the seal between safety device and the closure member is ensured by the double contact of the two members. Should the pressure inside container 4 increase, bracket 14 will further compress seal 8 which will be further deformed thereby ensuring a greater seal both in this second region and in the first region where flexible edge 10 is acting. In this manner, any possible leak between safety device 7 and the closure member will be prevented until the safety valve is activated. It has been seen in practice that the safety cap according to the invention is particularly advantageous in providing constant operation during a long time because it is not subjected to stretchings due to vapour leaks between the moving members or due to calcareous deposits on the connecting means between the grip member and the closure member. The materials employed, as well as the dimensions, may be any according to the specific needs and the state of the art. Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly, such reference signs do not have any limiting effect on the scope of each element identified by way of example by such reference signs.

Claims: Safety cap for pressurized containers (4) comprising a closure member (2) for closing the container aperture (3) and a grip member (5) having a connecting means (6) with said closure member for removing said closure member from said aperture only when the pressure inside the container has a preset value, a safety device (7) being slideable inside said closure member (2) from a first position to a second position, and vice versa, for activating and disactivating said connecting means as said pressure varies, seal means (8) between said closure member and at least a first and second regions (11,14) of said safety device, paid seal means acting in said first region (11), along a first direction which is substantially perpendicular to a sliding direction of said safety device (7), and in said second region (14) along a direction which is substantially parallel to said sliding direction of said safety device (7), characterized in that said seal means comprises a seal (8) having a main body, said main body having a circular shape and having an enlarged edge (9), on a first face, and a flexible rim (10), on a second face. Safety cap, according to claim 1, characterized in that said seal means (8) varies its seal rate according to the variation of said pressure. Safety cap, according to one or more of the preceding claims, characterized in that said seal means (8) act sequentially in said first region and in said second region. Safety cap, according to one or more of the preceding claims, characterized in that said flexible rim (10) acts on said first region of said safety device and in that said enlarged edge (9) is arranged in an annular seat (12) of said closure means. Safety cap, according to one or more of the preceding claims, characterized in that said second face of said seal acts on said second region of said safety device when said closure member is in said first position wherein said grip means is freely rotatable with respect of said closure means, said second region being defined by an annular bracket (14). Safety cap, according to claim 5, characterized in that said safety device has an annular seat (15) comprised between its external wall (11) and said bracket (14), said edge being arranged in said annular seat (15) when said closure member (2) is in said first position. Safety cap, according to one or more of the preceding claims, characterized in that said closure member (2) is in said first position when said pressure tends to the highest value and in that said member is in said second position when said pressure tends to zero. Safety cap, according to one or more of the preceding claims, characterized in that said connecting means comprises a bar (20) which is movable inside said grip means and is biased by an elastic means (22) for engaging and disengaging said closure member according to the motion of said safety device between said first position and said second position.

Inventors: DE LONGHI GIUSEPPE, DE'LONGHI, GIUSEPPE
Applicants: LONGHI SPA DE, DE' LONGHI S.P.A.
Application year: 1996
Main classification: F16J13
IPC codes: F16J13