SEALING MECHANISM FOR AN EVACUATED DEVICE, EVACUATED DEVICE AND METHOD FOR VACUUM TIGHT SEALING OF AN EVACUATED DEVICE

The present invention relates to a sealing mechanism for an evacuated device, an evacuated device and a method for vacuum tight sealing of an evacuated device.

In a preferred embodiment, the evacuated device is an evacuated solar panel and the mechanism and the method are adapted for sealing such a solar panel. Many commercial devices are known which operate under vacuum conditions. During manufacturing these devices are usually connected to vacuum pumps and at the end of the manufacturing process they must be disconnected from these vacuum pumps, without deteriorating their internal vacuum. In the case of metallic devices, metal valves could be used for this purpose. Nevertheless metallic valves are heavy, cumbersome and expensive. Therefore, to avoid these inconveniences, instead of the before mentioned metallic valves, the metallic evacuated devices are typically provided with a small diameter copper pipe (less than 10 millimetres) connecting the device to be evacuated to the vacuum pumps .

The device is thus evacuated (with the vacuum pumps sucking through the copper pipe) and, at the end of the pumping process, the copper pipe is squeezed and cut and

the cut lips of the copper pipe are welded; all these operations are implemented by a special tool in a single operation .

Nevertheless also this approach has some drawbacks, because the sealing cannot be reopened without losing the vacuum within the evacuated device. In addition the small pumping conductance of the copper pipe (i.e. the small diameter of the copper pipe) limits the achievable vacuum.

Moreover, the evacuated device may be sealed only once, because the copper pipe can be squeezed, cut and welded only once; thus if the evacuated device must be open, before it is sealed again the copper pipe must be replaced.

The technical aim of the present invention is therefore to provide a sealing mechanism, an evacuated device and a method for vacuum tight sealing of said evacuated device by which the said problems of the known art are eliminated.

Within the scope of this technical aim, an object of the invention is to provide a sealing mechanism, an evacuated device and a method which allow the evacuated device to be vacuum tight sealed after evacuation and after that to be reopened, without losing the vacuum.

This could be desirable for checking or maintenance operations . Another object of the invention is to provide a

sealing mechanism, an evacuated device and a method which allow a high or a very high vacuum to be reached within the evacuated device.

A further object of the present invention is to provide a sealing mechanism, an evacuated device and a method which allow the evacuated device to be vacuum tight sealed, reopened and subsequently closed again (also for many times) with no need of replacing any structural element of the device itself. The technical aim, together with these and further objects, are attained according to the invention by providing a sealing mechanism, an evacuated device and a method in accordance with the accompanying claims.

Further characteristics and advantages of the invention will be more apparent from the description of a preferred but non-exclusive embodiment of the sealing mechanism, the evacuated device and the method according to the invention, illustrated by way of non-limiting example in the accompanying drawings, in which: Figure 1 is a schematic view of a sealing mechanism connected to an evacuated device;

Figures 2A and 2B show two different embodiments of a support of a sealing element; and

Figures 3A and 3B show two different embodiments of a joint of the evacuated device.

With reference to the figures, these show a sealing mechanism 1 for an evacuated device 30.

The sealing mechanism 1 comprises a hollow body 2 having a first end 3 connectable to one aperture 32 of the evacuated device 30 to be sealed and a second end 5 connectable to a pumping unit 8 arranged to create the vacuum within the evacuated device 30.

The sealing mechanism 1 further comprises a support 9 which releasably holds a sealing element 12 of the aperture 32 of the evacuated device 30; the sealing element 12 is for instance shaped as a lid.

The support 9 is movable along an X axis between a sealing position in which the sealing element 12 is at the first end 3, and a pumping position (shown in figure 1) in which the sealing element 12 is away from the first end 3 and allows a gas flow to pass through the first end 3.

Advantageously, in the pumping position the passage area between the hollow body 2 and the sealing element 12 is very wide, such that the vacuum achievable within the evacuated device is also high.

Figure 2A shows a first embodiment of the releasable connection of the sealing element 12 to the support 9.

In this first embodiment the support 9 presents a supporting end 14 provided with at least one preferably annular magnet 16; the sealing element 12 is made of a

ferromagnetic material, such that the magnet 16 withhold the sealing element 12.

Preferably the said sealing element 12 has a side 17 provided with indented seats for housing the magnet 16, such that the magnet are housed in these seats when they are connected to the sealing element.

Figure 2B shows a second embodiment of the releasable connection of the sealing element 12 to the support 9. In this second embodiment, the support 9 presents a supporting end 14 provided with a spring fitting such as male/female elements connectable to corresponding female/male elements of the sealing element 12.

The support 9 comprises a stem defining the supporting end 14, while the rear portion of the stem opposite the supporting end 14 comes out of the hollow body 2 and is provided with a manipulating knob 25, which allows the stem to be moved along the X axis.

As shown in figure 1, in the pumping position the stem 9 has the supporting end 14 within the hollow body 2. In addition, a wall 27 at the first end 3 of said hollow body 2 is arranged to receive a heater 28 for melting a soft soldering metal or alloy; in a different embodiment the wall 27 at the first end 3 of the hollow body is provided with a fixed heater for melting the soft soldering metal or alloy.

Advantageously the heater is an electric resistance element .

The sealing mechanism is adapted to create a vacuum and vacuum tight sealing of an evacuated device. This evacuated device 30 generally comprises a hollow structure 31 arranged to be evacuated and a joint 33 for connecting the same evacuated device 30 to the vacuum pumping unit 8.

In addition, the joint 33 has a flange 35 arranged to receive the sealing element 12.

Figure 3A shows a first embodiment of the joint.

In this embodiment, the joint 33 has a large pipe 36 (when compared to the pipe to be squeezed of the known art) connected to the evacuated device and at the end of the pipe 36 the flange 35 is provided.

The flange 35 also has an annular recessed seat 38 for housing a soft soldering metal or alloy 39 such as indium or tin or tin lead alloys.

Figure 3A also shows the sealing element shaped as a lid with a protruding edge to be inserted into the seat 38 and sunk into the soft soldering metal or alloy 39.

Figure 3B shows a second embodiment of the joint.

Also in this second embodiment the joint has a large pipe 36 with a flange 35 at its end. The surface of the flange 35 is flat and the soft

soldering metal or alloy 39 is applied on such a flat surface .

In this embodiment the sealing element 12 is preferably circular in shape with no protruding edge. The flange 35 and/or a pipe 36 connecting said flange 35 to the device 30 are arranged to receive a heater 40 for melting the soft soldering metal or alloy.

Alternatively (or in addition) the flange 35 and/or the pipe 36 are provided with a fixed heater for melting the soft soldering metal or alloy.

In both cases the heater is preferably an electric resistance element.

The flange 35 is provided with means for vacuum tight connecting of the first end 3 of the sealing mechanism 1 through which vacuum is created and a sealing element is applied.

Such means could be commercially available flanges of various types equipped with a metal gasket.

The sealing mechanism disclosed is particularly adapted when the evacuated device is an evacuated solar panel .

The operation of the sealing mechanism to seal an evacuated device is apparent from that described and illustrated and is substantially the following. First of all the soft soldering metal or alloy 39 is

placed within the seat 38 of the flange 35 or placed on a flat surface of the same flange 35; in order to keep it in place, the soft soldering metal or alloy may be heated to melt a small portion thereof and fix it to the flange. Thus the mechanism 1 is applied to the flange 35 of the evacuated device 30 and a vacuum pumping unit 8 is connected to the second end 5 of the hollow body 2 of the sealing mechanism 1.

The stem 9 is drawn in pumping position and the vacuum pumping unit 8 is activated to create the vacuum within the evacuated device 30.

Thus, when the correct pressure in achieved within the evacuated device 30, electrical resistance elements are applied about the pipe 36 and/or the flange 35 of the evacuated device 30, and about the surface 27 of the hollow body 2 of the sealing mechanism.

These electrical resistance elements are activated such that the heat produced melts the soft soldering metal or alloy 39. The stem 9 is then moved from the pumping position to the sealing position; thus the stem 9 goes forwards until the sealing element 12 carried by the stem 9 penetrates the soft soldering metal or alloy.

The resistance elements are deactivated such that the soft soldering metal or alloy 39 cools and sealingly holds

the sealing element 12.

Thus the stem 9 may be withdrawn such that the magnet 16 disengages the sealing element 12 or the spring fitting of the stem 9 disengages the sealing element 12. Thus the sealing mechanism may be removed leaving the evacuated device vacuum tight sealed.

When an evacuated device is already closed and must be reopened for example for checking or maintenance operations, first of all the sealing mechanism first end 3 is connected to the flange 35 of the evacuated device (in this case the stem 9 is not provided with the sealing element 12) .

Thus the internal volume of the hollow body 2 of the sealing mechanism 1 is evacuated until the desired level of vacuum is reached.

The stem is engaged with the sealing element 12 connected to the flange 35; thus the electrical resistance elements are applied onto the sealing mechanism 1 and the soft soldering metal or alloy is melted. The stem 9 is withdrawn and the evacuated device is opened.

To close the evacuated device again it is sufficient to activate the electrical resistance elements again to melt the soft soldering metal or alloy and repeat the sealing sequence described above.

Advantageously the sealing element 12 and the surface around the aperture to be sealed (in particular the seat containing the soft soldering metal or alloy) are preliminary treated to render them soft soldering feasible, for instance by indium or tin or tin-lead coating.

The present invention also relates to a method for sealingly close an evacuated device.

The method consists in sucking air through an aperture of the evacuated device, melting a soft soldering metal or alloy and welding a sealing element closing said aperture by means of said soft soldering metal or alloy.

The sealing mechanism, the evacuated device and the method for sealingly close an evacuated device conceived in this manner are susceptible to numerous modifications and variants, all falling within the scope of the claims.

In practice the materials used and the dimensions can be chosen at will according to the requirements and to the state of the art.