The invention concerns a closing unit of an autoclave process chamber. The solution is designated particularly for steam autoclaves, especially of class B, but can also be used to close pressure tanks of various types.

Known are many solutions of a tight and secure pressure tank closing, including various structures and methods used to close an autoclave process chamber. O-ring or similar seals are most frequently used to ensure tightness between the cover and the chamber, where the seals are subject to initial compression when pressed and where the cover is put in the position which enables its closing. Irrespective of the structural details, tightness is secured in these solutions by pressing the chamber edge against the seal.

Known from European patent application published under No. EP0452603 is a device for closing pressure chambers in which the cover consists of the top part which rests on the edge of the chamber opening, and the bottom part connected thereto axial ly, as well as of an O-ring seal matching the circumferential edges of both parts of the cover. The seal gets pressed and fixed in place when the cover is in the closed position and both its parts are clasped together. The closing may be fitted with a calibration ring connected to the walls of the chamber opening, and if so, the seal gets compressed between the edge of the top part of the cover, bottom edge of the ring, and the inclined edge of the bottom part of the cover. The seal can also take the form of a flexible strip.

Disclosed in the European patent application published under No. EP0659942 is a sealing element of special construction, placed between the cover and the tank flange, it is given the form of a ring fitted with an apron directed towards the axis and reaching inside the tank opening. Moreover, the ring has grooves on its top and bottom wails, designated to accommodate seals of the O-ring type therein. Along its circumference the ring disc is fitted with a pressure-resistant stabilization tape. The top and bottom surfaces of the ring can have coaxial grooves. The element is made of a chemically-resistant material.

Presented in the European patent application published under No. EP0940146 is an autoclave with a chamber having walls which end with a flange on the chamber opening side, as well as a door closing the opening. The door adheres to the chamber opening via a ring sea! placed on the flange and resting on its protruding edge. The seal is V-shaped in cross section, where one of its resilient ribs is shorter and adheres to the flange, and the other rib is longer and adheres to the door surface. The flange is fitted with a drain opening. The opening is closed with an electromagnetic valve which prevents flow of condensate during the sterilization process and which opens the opening at the cycle end, thus enabling the outflow of the water which has accumulated around the seal.

The closing unit of an autoclave process chamber with a cover touching on the walls of the process chamber and fitted with fixing elements, as well as a sealing element between the cover and the process chamber wall according to the invention is characterised in that there is a protrusion formed along the edge of the process chamber wall on the side of the cover, where corresponding to the protrusion is the space between the outer and inner lips of the 'U'-shaped lip seal placed in the groove, the latter formed in the cover wall on the side of the process chamber.

Preferably, the protrusion along the edge of the process chamber wall is formed by a steady decrease of the wall thickness.

In another variant, the thickness of the process chamber wall changes stepwise as of the protrusion foot.

The groove in the cover is 'U'-shaped, where its width corresponds with the width of the foot of the lip seal, and the depth which corresponds with the height of the lip seal.

The width of the groove is the same along its entire height, and the width of the lip seal at the level of the lips is smaller than its width at the foot.

Preferably, the cross-section of the protrusion has the shape of an equilateral triangle with a rounded apex, and its thickness at the point where the distance from the apex is smaller than the depth of the space between the lips of the lip seal, is larger than the width of the space. The lip seal in the cover groove and the edge of the process chamber wall have circumferences in the shape of a rectangle with rounded corners.

The solution according to the invention is advantageous in that it ensures tightness and precision of the closing, in particular of an autoclave process chamber having shape other than circular in cross-section, in which there are problems with even distribution of forces generated when the pressure builds up.

An exemplary embodiment of the closing unit of an autoclave process chamber is illustrated on a drawing, where Fig. 1 shows the area of the autoclave process chamber closing in cross-section, Fig. 2 depicts the lip seal in cross-section, Fig. 3 a, b shows a cross-section of the process chamber wall edge in two variants, Fig. 4 shows the view of the cover with the sealing element from the perspective of the process chamber, and Fig. 5 presents a cross-section of the cover with the sealing element.

In the exemplary embodiment illustrated on the drawing the solution according to the invention envisages the closing of a process chamber placed inside casing A of a steam autoclave and fitted with necessary fixing, positioning, insulating, and other elements. In cross-section, the space of the process chamber K has the shape of a rectangle with rounded corners and is delimited by a wall 1 of the process chamber and cover 2. The thickness of the process chamber wall 1 on the side of the cover 2 decreases steadily and symmetrically on both sides, thus forming a protrusion 3 along the edge of the process chamber wall, as shown on Fig. 3 a. In longitudinal section, the protrusion 3 formed around the circumference of the edge of wall of the process chamber has the shape of an equilateral triangle with rounded apex and is formed by truncating the wall on both sides along its entire circumference. In another embodiment variant the protrusion 3 along the edge of the wall 1 of the process chamber can be formed through decreasing the thickness of the wall stepwise, as shown on Fig. 3b. Cover 2 which closes the space of the process chamber K in an autoclave has a groove formed along its circumference, on the wall on the side of the process chamber K, where the groove accommodates the lip seal 4. In circumference, the groove with the lip seal 4 follows the shape of a rectangle with rounded corners, corresponding to the shape of the edge of the process chamber wall 1. Both the groove in the cover 2 and the lip seal 4 have the shape of the letter 'U' in cross-section, where the depth of the groove corresponds with the height of the lip seal 4 and the width of the groove is equal along the entire depth, corresponding to the width of the foot of the !ip seal 4. The width of the lip seal 4, on the other hand, decreases on the outside on both sides, i.e. towards the outer lip seal 5 and the inner lip seal 6, as shown on Fig. 2. Thanks to the decreasing width of the lip seal 4, when the lip seal is placed in the groove in cover 2, there is some free space left between the side walls of the groove and the seal. The space between the outer lip 5 and inner lip 6 is rectangular in cross-section. The dimensions of the spaces between the lips of the lip seal 4 and the protrusion 3 are designed so that the lips 5, 6 part when the protrusion 3 is entered in the lip seal 4. In an advantageous variant, the thickness of the protrusion 3 at the point where the distance from its apex is shorter than the depth of the inner space of the lip seal 4, is larger than the width of that space. Depending on the requirements as to the construction of cover 2, the groove for the lip seal 4 can be shaped in a solid, monolith wall, or delimited by the wails of individual elements forming the cover 2, where the elements serve additional functions, such as the supportive, insulating, or blocking function etc. In the exemplary embodiment the dimensions of the process chamber in cross-section and of the corresponding circumference of the groove with the seal are ca. 200x60 mm, the depth/ height of the groove and the seal is ca. 6.5 mm, and the width at their feet is 8 mm, the width of the space between the seal lips is 3 mm, and the width of the space between the seal lip and the groove wail is ca. 1 mm. The angle between the walls of protrusion 3 on the edge of the process chamber is ca. 30°, and the thickness of the protrusion is ca. 2.5 mm at the point where the distance from the apex shorter than the depth of the space between the seal lips. The materials used to make individual elements are selected to satisfy the requirements and match the working parameters of a specific autoclave. In the exemplary embodiment, the walls of the process chamber are made of metal, preferably aluminium, the cover consists of a number of interconnected aluminium and plastic elements, and the seal is made of silicone.

When the cover 2 is being closed, the edge of the process chamber wall 1 formed into the protrusion 3 parts the iips of the lip seal 4 in the cover 2, in effect of which the seal holds the protrusion 3 along the edge of the process chamber wall 1. Then, the user blocks the cover in place with appropriate elements, by e.g. locking the bolts inserted in the elements connected to the process chamber. The construction of the closing unit according to the invention ensures self-guiding of the cover and precise matching of the chamber wall edges in the cover seal, which facilitates correct closing of the process chamber and ensures its tightness without the need to pre-compress the seal. At the same time, thanks to the shapes of the seal and the protrusion it is possible to introduce the edge of the process chamber wall in between the lips of the seal without folding it, which might damage the seal or affect its tightness. The solution is designated especially for autoclaves class B, in which the sterilisation process develops in sequences of vacuum and steam injections, with steam overpressure maintained so as to heat up the load and sterilize it, followed be a sequence of underpressure to dry the sterilised load. The construction of the closing ensures its tightness in any conditions thanks to the seal lips which adhere as follows to the surfaces of the process chamber walls when subject to pressure: in overpressure, the inner lip 6 of the lip seal 4 is pushed outwards and adheres to the inner surface of the process chamber wall 1, and in underpressure the outer lip 5 of the lip seal 4 is sucked inwards and adheres to the outer surface of the pressure chamber wall 1.