Patent Grant
7579607
The present invention relates to an installation for sterilizing articles, and more particularly but not exclusively for sterilizing bottles.
Installations for sterilizing articles, in particular trays for food products, are known, such an installation comprising an enclosure with a conveyor passing therethrough having the articles disposed thereon, and an electron bombardment device disposed above the conveyor for treating the articles with vertical radiation. Such installations are satisfactory for articles of small height, and they enable articles to be sterilized while using low-energy electron radiation.
In contrast, when the articles are of considerable height and/or thickness, for example when the articles are bottles, it is necessary to increase the electron bombardment energy very considerably so that the electron radiation can reach the bottoms of the bottles after passing through their walls and still have enough energy to ensure sterilization at the bottoms of the receptacles. With bottles, the electron bombardment energy also needs to be increased because the neck of the bottle absorbs a fraction of the electron radiation energy before it reaches the bottom of the bottle. High-power electron bombardment then raises the problem of deteriorating the portions of the article that are closest to the bombardment device, in particular the neck when the article is a bottle.
It is also known from document U.S. Pat. No. 4,944,132 a sterilization installation comprising two electron bombardment members disposed at different orientations relative to the articles that are to be sterilized but both emitting a horizontal radiation over receptacles extending vertically. The bottom of a bottle would not be satisfactorily sterilized with an installation according to this document.
In addition, high-power electron bombardment runs the risk of propagating outside the enclosure and thus of constituting a danger for operators moving around the installation.
A main object of the invention is to provide an installation for sterilizing articles that enables the articles to be sterilized sufficiently both internally and externally by means of electron bombardment, and while minimizing deterioration of an article due to the electron bombardment.
Other aspects of the invention seek to minimize the propagation of electron radiation outside the enclosure, and to minimize the penetration of pollution into the inside of the enclosure.
In order to achieve the main object of the invention, the invention provides an installation for sterilizing articles, the installation comprising an enclosure having an inlet opening and an outlet opening, a support device for moving the articles inside the enclosure with a vertically extending longitudinal axis, and at least two electron bombardment members disposed at different orientations relative to the articles that are to be sterilized to process the articles as they move through the enclosure, wherein the electron bombardment members are inclined relative to a longitudinal axis of the articles.
Thus, by appropriately positioning the electron bombardment members as a function of the shape of the article to be sterilized, it is possible to ensure that the electron bombardment member is facing a portion of the article that is of small thickness, thus making it possible to ensure that all portions of the article are sterilized, while using electron bombardment at low energy. This enables a complete sterilization of the article, including the bottom of a receptacle, without deterioration of the article.
In another aspect of the invention, the support device comprises at least two support members disposed to support the receptacles in various positions corresponding to respective electron bombardment members, and preferably, the support members are rotary platforms disposed to cause the articles to follow an S-shaped path. This ensures that the support members do not form obstacles to propagation of the radiation while an article is passing in front of the corresponding electron bombardment member.
In yet another advantageous aspect of the invention, the enclosure has side walls presenting a curvilinear or zigzag profile. This ensures that the electron radiation is subjected to a large number of reflections on the walls of the enclosure before reaching the inlet opening or the outlet opening, such that the radiation escaping from the enclosure has residual energy that is low enough to constitute no danger for operators moving around the installation.
According to yet other advantageous aspects of the invention, the enclosure includes wall elements disposed to minimize the flow of air inside the enclosure, and the installation includes a device for injecting a sterile gas into the inside of the enclosure, preferably disposed vertically above the articles. This simultaneously minimizes the amount of polluted air that penetrates from outside the enclosure and the amount of electron radiation that is emitted outside from the enclosure.
Other characteristics and advantages of the invention will appear on reading the following description of a preferred, non-limiting embodiment of the invention given with reference to the accompanying figures, in which:
The invention is described below with reference to an installation for sterilizing bottles 1.
In the embodiment shown, the installation has two bottle-support members comprising in conventional manner a rotary platform 2 (not shown in
The rotary platforms 2 are disposed adjacent to each other and are driven to rotate in opposite directions. The grips 6 are also controlled in conventional manner by a control member (not shown) enabling the bottles to be transferred from one rotary platform to the other as they pass through the point where the rotary platforms are tangential to each other, so that the bottles follow an S-shaped path, as shown in
An enclosure 7 extends around the support members and defines a volume around the receptacles that enables the receptacles to travel inside the enclosure while they are being carried by the grips 6.
As shown, the enclosure 7 preferably comprises a cover 8 secured to the frame of the installation by means that are not shown, and a vessel 9 that comprises a cylindrical outer side wall 10 associated with each rotary platform 2 together with a cylindrical inner side wall 11 connected to a bottom wall 12. On either side of the point where the rotary platforms 2 are tangential, the outer side walls 10 are interrupted and are united with one another in leaktight manner so as to define a connection opening 33 between the two portions of the enclosure, each portion being associated with a respective rotary platform 2. The vessel 9 is carried by a vertically movable plate 13 connected to the frame 5 via screw actuators 14 enabling the vessel to be moved between an open position shown in
The outer wall 10 of the enclosure is pierced by an inlet opening 15 facing a bottle insertion rotary device 16, e.g. a transfer star, having radial partitions 17 that are spaced apart by a distance that is small enough to ensure that two radial partitions 17 are continuously adjacent to the edges of the opening 15. The radial partitions 17 thus minimize a risk of polluted outside air penetrating into the inside of the enclosure, and they also constitute obstacles to any of the electron radiation that is being reflected inside the enclosure managing to leak out. In an opposite zone of the enclosure, the installation includes a rotary device 18 for extracting bottles from the enclosure. The rotary extractor device 18 faces an outlet opening 23 formed in the outer side wall 10 of the enclosure. Like the rotary device 16, the rotary device 18 includes radial partitions 19 forming obstacles to outside air penetrating into the inside of the enclosure. In addition, at the ends of dead zones 20 in which the grips 6 do not carry any bottles, the vessel has radial partitions 21 that are cut so as to allow a platform 2 to rotate together with the associated grips 6 while minimizing any risk of polluted external air penetrating via the corresponding dead zone 20.
In two zones that are radially opposite relative to the path of the bottles 1, the installation has two electron bombardment members 24, each disposed in a housing 25 that is secured to the cover 8 in order to emit electron radiation 26 at 45° relative to the vertical longitudinal axes of the bottles 1. The electron radiation 26 penetrates into the enclosure 7 via an opening 27 in the outer side wall 10 of the enclosure. Like the enclosure, the housing 25 is preferably made with an inner lining of lead. In order to ensure continuity between the housing 25 and the vessel of the enclosure, the enclosure includes a casing element 28 of appropriate shape that is secured to the vessel 9. Facing the terminal member 24, the inner wall 1 of the vessel 9 is preferably reinforced by a piece of lead 29 that absorbs direct electron radiation so as to prevent it from propagating through the inner side wall of the enclosure.
Furthermore, an injector pipe 30 is associated with each grip 6. Each injector pipe 30 has one end opening out vertically above a bottle 1, and an opposite end connected to a rotary joint 31 enabling the injector pipe 30 to be fed with a sterile gas under pressure from a gas source that is not shown. The sterile gas is preferably nitrogen, thereby enabling ozone production during electron bombardment to be reduced. The sterile gas under pressure also raises the pressure inside the enclosure 7 so as to minimize any penetration of external air. In order to ensure that the pressure inside the enclosure does not become too great, the cover 8 is preferably fitted with an extractor orifice 32.
Naturally, the invention is not restricted to the embodiment shown and can be the subject of variants in implementation without going beyond the ambit of the invention as defined by the claims.
In particular, although the sterilization installation is described as being for sterilizing bottles, it could be used for sterilizing any kind of article, the articles being supported by an appropriate support device. Although the sterilization installation of the invention is shown as having two electron bombardment members associated with two rotary support members, the number of electron bombardment members should be adapted to the shape and the size of the articles in order to achieve the desired sterilization, while minimizing the number of electron bombardment members. It is also possible to associate a plurality of electron bombardment members with a single support member if the configuration of the support member and the shape of the articles for sterilization make that possible.
Although the enclosure of the invention is described as having side walls that are cylindrical, it would be possible to use an enclosure having side walls of curvilinear or zigzag profile so as to ensure that the electron radiation is subjected to successive reflections on the walls of the enclosure, thereby reducing the intensity of the radiation before it reaches the inlet orifice or the outlet orifice of the enclosure.
Although the invention is described with reference to electron bombardment means emitting radiation at 45°, the value of this angle of inclination within the range from 0° to 90° with respect to the vertical direction of the longitudinal axes of the articles should be adapted to the shape of the articles to be sterilized and to their wall thickness when the articles are receptacles.
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