Device for holding and discharging liquid and paste-like substances under pressure

Abstract

A device for holding and discharging liquid and pastelike substances is disclosed. The device has a rigid outer container and a flexible inner container. The upper edge of the inner container is fastened to the outer container. The inner container is intended for holding the substance to be discharged, a discharge valve being in communication with the inner container. A propellant is introduced into the space between the containers for exerting pressure on the inner container. For assuring complete removal of the substance held in the inner container, and complete collapsing of the inner container, the peripheral wall of the latter is provided with longitudinal deformations in the form of recesses or depressions.

Description

The invention relates to a device for holding and dispensing liquid and paste-like substances under pressure, comprising a rigid outer container and a flexible, preferably aluminum, inner container whose upper edge is fastened to the outer container, and having a discharge valve disposed in the top of the outer container and protruding into the inner container and a sealable opening in the base of the outer container for the introduction of a propellant.

In these devices, also known as twin-chamber aerosol containers, the resilient inner container contains the useful goods while the annular space between the inner and the outer containers is filled with the propellant, i.e. with pressurised gas. The useful goods can be, for example, cosmetics, a perfume spray, an insecticide, lacquer or even a paste-like foodstuff such as liver-sausage or honey. For discharging these goods, the discharge valve, which may be fitted with a spray nozzle, is opened, for example, by pressing or tilting. The pressure exerted by the propellant on the inner container takes effect and forces the useful goods out of the inner container through the discharge valve. There is a risk here that the inner container may become constricted at its end facing the discharge valve which would prevent the useful goods below the constriction from reaching the discharge valve. Thus, the inner container would not be completely emptied. Another danger is that the inner container might become constricted and fold along irregular bending or buckling lines at which points it may crack. The resulting contact between the useful goods and the propellant may render the goods useless. In addition to the loss of propellant which may occur, the device would be rendered unserviceable as a result of this mixing.

A previously proposed method of avoiding these difficulties is the use of distance bars which extend from top to bottom in the inner container and end above its base. These distance bars prevent the inner container from becoming completely constricted. However, there is the risk that, if the base of the inner container folds upwards, it may be pierced by the distance bar. This too immediately renders the entire device useless and the goods still contained in it are lost.

To prevent the inner container from being pierced, frame-like spreading rings have also been inserted into the inner container. These spreading rings cannot pierce the inner container. However, they do not prevent the inner container from becoming completely constricted at every point so that a pocket filled with the useful goods can still arise below the constriction. The goods contained in this pocket cannot pass the constriction and remain in the inner container. Such goods are lost. The useful life of the device is reduced accordingly.

The invention sets out to provide a device such that the inner container does not become constricted to form a pocket which cannot be emptied or cracked along sharp bending or buckling lines, and does not become pierced by a distance bar, but is such that it can discharge its entire content of useful goods down to substantially the last drop through the discharge valve without there being any risk of the inner container folding sharply and as a result cracking.

According to the present invention, longitudinal deformations are provided equally distributed round the peripheral wall of the inner container.

When discharging its content the inner container contracts inwardly along those deformations uniformly over its entire length. The possibility of a constriction occuring at any point and leading to the formation of a pocket below this constriction is substantially eliminated. The entire content of the inner container can be freely discharged.

In preferred embodiments the deformation are formed by recesses. In a horizontal or transverse cross section these recesses preferably have the form of hollow depressions which look like gently sloping valleys.

The inner container does not apply the same resistence against the external pressure of the propellant on the surface of these depressions as it does on the surface between these depressions, where as before it is circular shaped. This means that the inner container is preformed and weakened in advance on the surface of its depressions so that the pressure of the propellant affects this part first of all. The inner container is compressed uniformly over the surface area of these depressions which is large compared to the surface area of a buckling line. The possibility of a buckle or fold along a sharp edge which could lead to cracking is minimized. It is just as unlikely that the inner container will become constricted at any plane. The large surface of the depressions is sufficient for the pressure of the propellant to act on. It is no longer possible, when the discharge valve is suddenly opened, for the resulting alteration in pressure to affect only a limited surface of the inner container and compress or constrict it there.

It has proved practical and sufficient to provide four depressions disposed at 90.degree. from one another about the inner container wall.

The depressions can end a short distance above the base and below the upper edge of the inner container.

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

FIG. 1 is a longitudinal section of a dispenser according to the invention; and

FIG. 2 is a cross section along the line 2--2 of FIG. 1.

The dispenser shown in FIG. 1 has a rigid outer container 12 with a base 14 and a filling valve 16 disposed in an opening in the base for the introduction of the propellant. Inside the rigid outer container 12 is a flexible inner container 18. The upper edge of the inner container 18 is flanged round the upper edge of the outer container 12 and is held there by an outer container cap 20. A discharge valve 22 is located in this outer container cap 20. Four longitudinal depressions 24 are constructed in the wall of the inner container 18. FIG. 1 shows that these depressions begin slightly above the base 26 of the inner container 18 and end shortly below the upper edge of the inner and outer containers. As can be seen particularly clearly in the transverse cross-section shown in FIG. 2, the depressions 24 look like gently sloping valleys.

The annular cavity between the outer container 12 and the inner container 18 and the space between the base 26 of the inner container 18 and the base 14 of the outer container 12 is filled with propellant through the filling valve 16. The flexible inner container 18 is, therefore, under the pressure of this propellant. Its interior is filled with the useful goods. When the discharge valve 22 is actuated, the pressure of the propellant acts firstly on the surfaces of the depressions 24 as can be guessed from the section shown in FIG. 2. While the goods are being discharged through the discharge valve 22 the inner container gradually folds inwards on the surface of its four depressions 24. Finally, it assumes the approximate shape of a star. This star has the same section throughout the entire length of the inner container so that the contents too have left the inner container uniformly and smoothly.

The advantages of the present invention, as well as certain changes and modifications to the disclosed embodiment thereof, will be readily apparent to those skilled in the art. It is the applicant's intention to cover all those changes and modifications which could be made to the embodiment of the invention herein chosen for the purposes of the disclosure without departing from the spirit and scope of the invention.

Claims

What we claim is:

1. In a device for storing and discharging fluid and paste-like substances comprising a rigid outer container and a generally cylindrical, flexible metal inner container having inner and outer surfaces and positioned within said outer container to define a space therebetween, pressure means in said space, and discharge valve means communicating with said metal inner container, said device being operative upon actuation of said discharge valve means to discharge contents of said metal inner container under the action of said pressure means thereon, said pressure means collapsing said metal inner container as the contents thereof are discharged, the improvement comprising: longitudinal weakening deformations of arcuate cross-section formed in said metal inner container to cause said pressure means, upon actuation of said discharge valve means, to fold said metal inner container inward by said action of said pressure means on the outer surfaces of said longitudinal weakening deformations in preference to the remainder of said outer surface of said metal inner container.

2. A device as claimed in claim 1, in which said longitudinal weakening deformations are formed by recesses.

3. A device as claimed in claim 1, in which four longitudinal weakening deformations are provided, offset at 90.degree. relative to one another.

4. A device as claimed in claim 1, wherein said metal inner container comprises a base and an upper edge, and in which said longitudinal weakening deformations end slightly above said base and slightly below said upper edge of said metal inner container.

5. A device as claimed in claim 4, in which said upper edge of said metal inner container is connected to said outer container at the upper edge thereof.

6. A device as claimed in claim 1, in which said metal inner container is made of aluminum.