Spherical Containers For Pressurized Fluids

Abstract

A pressurized fluid container of generally spherical shape, wherein at least one depression is provided in a wall of the container for outward expansion should the pressure within the container exceed a nominal value.

Description

This invention concerns spherical containers for pressurized fluids, more particularly, portable containers for a pressurized liquefied combustible gas of the type used in cooking, lighting, domestic heating, travelling and camping apparatus.

It is desirable to use the least possible amount of metal for manufacturing this type of container in order to make it as light in weight as possible and to reduce the manufacturing costs thereof to a minimum, a feature which is particularly important when these containers are disposable, i.e. intended to receive a single charge of pressurized fluid and to be subsequently thrown away as waste packing when they are empty.

Due to the spherical shape of the container, maximum capacity with minimum wall surface is obtained at the same time as maximum resistance of these walls to internal over-pressure.

However, since a plain spherical container is not capable of any deformation liable to increase its capacity, it is not suitable in this form for the proposed use.

It is also desirable that the condition of such containers should be subject to continuous inspection, particularly when they are stocked in places where the temperature could cause the internal pressure to rise dangerously.

According to the present invention, a container of generally spherical shape is characterized in that at least one visible depression is provided in the side of the container capable of expanding outwardly in the event of the internal pressure rising above a nominal value, the or each depression being disposed between the equatorial plane of the container and at least one of its two polar zones which may be reserved for receiving means of removing fluid and, if desired, for providing a stable base.

In one preferred embodiment, the or each depression has the shape of a spherical cup.

It is desirable to provide several such depressions equiangularly spaced over at least one of the hemispheres, about its polar axis, particularly the upper hemisphere, so that at least one depression is always visible whatever may be the position of the observer about the vertical polar axis of the container.

In order to utilize the cap or cup-shaped depressions for stacking containers, four of them should be centered on the same circle about the polar axis of the upper hemisphere, each of these depressions being co-axial with a radius of the container subtending, with the vertical polar axis thereof, an angle slightly less than 30.degree..

Another depression in the form of a spherical cap may be co-axial with the pole of the lower hemisphere in order to serve as a stable base for the container when placed on an even surface.

In a further embodiment of the invention, the or each depression is of annular form extending around the polar axis of the container.

It may be advantageous to provide several such annular depressions extending at least over one of the two hemispheres of the container in circles parallel to the equatorial plane thereof.

In another embodiment of the invention, at least the upper hemisphere of the container is provided with depressions in the form of a series of folds which converge from the horizontal equatorial plane towards the upper polar zone of the container.

The container may be formed from two hemispheres connected together in air and water-tight relationship by welding, for example, along their equatorial joining edges, which, being disposed outside the areas of the container deformed by the depressions, retain a strictly circular form, thereby contributing to the strength of the joint, since the stresses which the internal pressure of the container may place on this joint are then strictly limited to hoop stresses.

Alternatively the container may be produced by hydro-forming from a single sheet of metal the localized depressions in the upper hemisphere of the container then acting to provide the necessary shaping of the sphere.

However, the depressions, whether they are obtained by stamping out, hydroforming or the like, do not reduce the thickness of the material of the wall of the container and thus do not affect its strength. They also retain their strength when, as a result of internal over-pressure in the container, they expand ouwardly since the deformation is effected without stretching and consequential reduction of the wall thickness. Furthermore, this deformation increases the total capacity of the container and, consequently, immediately reduces the internal pressure, thereby increasing the safety of such a container.

The invention will now be described further, by way of example, with reference to the accompanying drawings, in which:

FIG. 1 is a vertical section through a first embodiment of the container according to the invention;

FIG. 2 is a corresponding plan view;

FIG. 3 shows schematically an arrangement of stacking a number of containers constructed according to another embodiment;

FIG. 4 is an elevational view of another embodiment;

FIG. 5 shows partly in elevation and partly in section, a container constructed according to another embodiment of the invention;

FIG. 6 is a view similar to FIG. 5 of a container constructed according to yet another embodiment of the invention; and

FIG. 7 is a partial section on the line III--III of FIG. 6.

The drawings show various embodiment of container, all of which are of generally spherical shape and have at least one visible depression capable of expanding outwardly in the event of the internal pressure rising above a nominal value, the or each depression being disposed between the equetorial plane of the container and at least one of its two polar zones which may be reserved for receiving means for the extraction of fluid and, if desired, for providing a stable base.

In the embodiment of the invention shown in FIG. 1, a number of depressions 6 have the shape of a spherical cap. Due to this shape, the depressions give effective resistance to internal pressure without being subjected to any deformation until such time as this pressure clearly exceeds a nominal value, in which case its curvature is reversed, passing from concave to the convex shape, thereby increasing the capacity of the container and resulting a in reduction of the internal pressure. It will be noted that this transition from the concave form to the convex form of the depression is effected without stretching and reduction of the wall thickness that is to say, without local weakening the wall.

Several equidistant depressions 6 are preferably provided over at least one of the hemispheres 1, 2 about its polar axis, so that at least one of the depressions 6 remains visible whatever the position of an observer may be relatively to the axis.

The container of FIG. 1 has two hemispheres 1 and 2 of which each is provided with several depressions 6 distributed in this manner.

In another particularly advantageous embodiment, the depressions 6 are arranged in such a manner that they may facilitate stacking of containers in a box, for example, or any other packing. For this purpose, four depressions 6 are provided on only one of the hemispheres preferably the upper hemisphere 1, these spherical cups, centered on a radius of the container, subtending, with the vertical polar axis thereof, an angle slightly less than 30.degree., the depressions themselves having a radius of curvature equal to or less than that of the container.

Each depression 6 can then be used to receive and center a portion of the surface of another similar spherical container, as shown in FIG. 3. It may be seen from this Figure that a container A may thus be surrounded by six containers B, the centers of the seven containers being located in the plane of the drawing. If the centers of two adjacent peripheral containers B are connected to that of the container A, it could be expected that they would become disposed on the apices of an equilateral triangle. However, as the upper and lower containers B and the container A penetrate each other partially at the point of their depressions 6, while the two containers B situated at the same level as the container A have no depression at the point where they could come into mutual contact with container A, the depressions 6 are designed to be centered on the radii of the corresponding container which substend with its vertical polar axis an angle which is not equal to 30.degree., but only slightly less, depending on the dimensions of the depressions in question.

The polar zone of the upper hemisphere 1 of the container may be punched out in its center with an aperture 5 capable of receiving a flap valve device with or without a perforable cover.

Alternatively, the punched hole need not pass through the wall, the base of the resultant depression itself representing a perforable cover.

The punching may also result in an actual shape, by producing a kind of socket capable of then being tapped for receiving the end of a normal gas supply with an automatic flap valve and removable sealing plug.

In some cases it is preferable to provide the lower hemisphere 2 with a single depression in the form of a spherical cup 6', as shown in FIG. 4, centered on the lower pole of the container and the edge of which provides a stable seat for it. As the depression 6' will not be visible in practice for checking an internal overpressure capable of affecting the strength of the container, it cannot substitute the depressions 6 distributed over the upper hemisphere 1 in the manner already described with reference to FIGS. 1, 2 and 3.

In any case and whatever embodiment is adopted, the container can be very readily assembled from two hemispheres 1 and 2, obtained separately with their depression 6 and, if desired, the depression 6' and the aperture 5, by stamping or hydroforming or the like.

It is therefore only necessary to unite the two hemispheres in question at their respective equatorial edges 3 and 4 by welding, hard soldering or by a mounting arrangement, possibly combined with a welding or hard soldering operation.

It will be appreciated that the edges 3 and 4 which are remote from the depressions 6 are perfectly circular, a feature which not only facilitates assembly which may be effected without necessitating angular keying or alignment of the two hemispheres relatively to each other about their common polar axis, but also makes it possible to obtain a very strong air-tight joint,since the stresses resulting from the internal pressure of the container are exerted on this joint only in the form of hoop stresses and not in the form of local flexing stresses such as would result from a connecting line deviating from a circular form.

In certain cases, it may be an advantage to provide a form different from that of a spherical cup for the depressions for checking and compensating internal overpressure.

In the embodiment shown in FIG. 5, depressions 8 are provided in annular form extending about the polar axis of the container and preferably located on the upper hemisphere 1. It will be noted that in this case only one depression 8 would be sufficient to indicate to an observer, at any position about the polar axis of the container, an abnormal internal over-pressure by its deformation.

In the case shown, the upper hemisphere 1 is provided with three depressions 8 extending around the polar axis in parallel circles.

If, in these conditions, a container charged for example with butane or propane, is kept in a place where the temperature rises unduly, causing a dangerous rise of the internal pressure, the depressions 8 are re-absorbed, increasing the distance of the upper pole from the equatorial plane, thus giving warning of the danger.

In the embodiment of the invention shown in FIGS. 6 and 7, the upper hemisphere 1 of the container is provided with a plurality of elongate depressions 9 which converge from the horizontal equatorial plane towards the upper polar zone of the container.

These depressions 9 which form a series of folds, also demonstrate to an observer by their deformation, whatever the position of the observer may be about the polar axis of the container, that the internal pressure therein may exceed the pressure for which it was designed.

It will be appreciated that, particularly when the depressions are formed by the folds 9, they may facilitate the manufacture of a container by hydroforming from a single piece of metal sheeting, since they act to accommodate the hammering to which in any case the upper hemispherical wall unit must be subjected above the horizontal equatorial plane of the container in order to provide it with its spherical shape. It will be appreciated that in all the embodiments proposed above, it is possible to construct the container of relatively thin metal sheeting by selecting the shape of the depressions to suit the thickness of said metal sheeting and its mechanical strength in order to ensure that, in the event of dangerous over-pressure within the container, it can reverse the depressions to provide the outer surface of the container with swellings which give an immediately visible indication of this abnormal situation. In this manner, a kind of alarm system is obtained, the pressure of which may be of value for revealing an excess filling, overheating of the containers and so on. Experience has shown that the depressions do not weaken the container so that the bursting pressure thereof is no less than that of a similar container without depressions, all other conditions being equal, but that, even if no notice is taken of the warning given by the appearance of the swellings, said swellings, by increasing the capacity of the container, reduce the danger of the container bursting.

It should be understood that the foregoing description has been given only by way of example and in no way limits the scope of the invention, and the described details of construction can be replaced by any other equivalent details.

Claims

I claim:

1. A container of generally spherical shape for pressurized fluids, particularly for pressurized liquefied combustible gases, wherein at least one visible depression is provided in a wall of the container each said depression being capable of expanding outwardly in the event that the pressure within the container rises above a nominal value, each depression being disposed between the equatorial plane of the container and at least one of its two polar zones, one of which is reserved for receiving means for the extraction of fluid; and wherein a plurality of elongate depressions are formed at least in an upper hemisphere of the container, said depressions being formed by a series of folds converging from the equatorial plane towards a polar zone of the container.

2. A container of generally spherical shape for pressurized fluids, particularly for pressurized liquefied combustible gases wherein there are provided equi-angularly distributed about its vertical polar axis over at least one hemisphere, depressions in the form of spherical cups, useful for stable stacking up the containers in several levels, one container beside and over others, each container of an upper level resting at least along a circular edge of one of said depressions against similar containers staggered side by side on a lower level, one container projecting by a part of its general spherical shape into the depression of another container.

3. A container of generally spherical shape for pressurized fluids, particularly for pressurized liquefied combustible gases wherein there are provided equi-angularly distributed about its vertical polar axis over its upper hemisphere four depressions in the form of spherical cups, useful for stable stacking up the containers in several levels, one container beside and over others, each container of an upper level projecting by a part of its general spherical shape into one of the cup shaped depressions of one of four similar containers arranged side by side on a lower level.

4. A container as specified in claim 3, in which each of said depressions is coaxial with a radius of the container which subtends with the polar axis thereof an angle less than 30.degree..

5. A container as specified in claim 3, comprising further in its lower hemisphere, around its vertical polar axis, a depression in the form of a spherical cup, the circular edge of which is useful as a stable seating of the container on a substantially horizontal plane, so as to place the depressions on the upper hemisphere of the same container all on a same level, on which they will receive a part of the generally spherical shaped superposed containers of an upper level.

6. A container as specified in claim 5, comprising further in its apex, between the said depressions, means for the extraction of fluid on a part of the container when this means will be preserved from any contact with adjoining similar containers in stacked up relation.

7. A container of generally spherical shape for pressurized fluids, particularly for pressurized liquefied combustible gases, wherein at least one of the two hemispheres surrounding its vertical polar axis comprises depressions of annular form extending about said axis in circles parallel to the equatorial plane of the container.

8. A container of generally spherical shape for pressurized fluids, particularly for pressurized liquefied combustible gases, wherein at least one of the two hemispheres surrounding vertical polar axis comprises a series of folds converging from the equatorial plane towards a polar zone of the container and which are capable of expanding outwardly in the event that the pressure within the container rises above a nominal value, at least one of the two polar zones of the container being reserved for receiving means for extraction of fluid.