Abstract:
A sterilizing container for holding surgical instruments or other sterilizing material during sterilization and for maintaining the sterilized condition during storage and transportation. The container has a body portion with at least one opening to permit exchange of media during the sterilization process. The filter is fitted in a sealing manner into the opening and permits at least a limited exchange of media and forms a barrier to microorganisms during storage. A self-closing inlet valve is provided so as to open toward the inside of the container when a predetermined pressure difference between external pressure and internal pressure is exceeded. A self-closing outlet valve is provided so as to open outward when a predetermined pressure difference between internal pressure and external pressure is exceeded. The filter is clamped in a holding frame and is supported all around on the holding frame with a form fit. The holding frame in turn is clamped on the edge of the container opening. At least the inward valve is arranged inside the holding frame.

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to a-sterilizing container for holding surgical instruments or other sterilizing material during sterilization and for maintaining the sterilized condition during storage and transportation. During sterilization, such sterilizing containers must permit exchange of media inside the sterilizer. 
     In order to permit exchange of media, it is known to equip the sterilizing containers with double valves which, during the sterilizing process in the sterilizer, alternately open and close depending on the pressure difference, and which, after the sterilizing process, remain closed in order to protect the sterilized material from penetration of microorganisms during storage. Such sterilizing containers are known, for example, from DE-B 1,217,550, DE-B 1,217,551 and DE Patent 1,642,161 and DE Patent 3,202,430. Other known sterilizing containers have container openings which are equipped with a filter through which the exchange of media takes place during the sterilizing process in the sterilizer, and which, after completion of the sterilizing process, are intended to form a barrier to penetration of microorganisms during storage of the sterilizing container. Such sterilizing containers are known, for example, from DE 3,438,463 C2. From this patent specification, it is also known to mount a filter leaf and a spring-preloaded filter holder plate in such a way that when a predetermined pressure difference is exceeded, the filter leaf can be lifted up like a valve from the cover openings, thus establishing a secondary flow route. A bypass is thus created as soon as the external pressure becomes so high that there is a danger of the container being squeezed together. 
     Such an overpressure valve is also proposed in DE 4,125,673 C1. This overpressure valve, which opens toward the inside of the container when a predetermined external pressure is established, can be pushed into a guide on the container wall. A filter assigned to a further container opening can be pushed into a similar guide. 
     This valve/filter combination known from DE 4,125,673 C1 and other valve/filter combinations are intended only as protective means for preventing the container from being squeezed together. 
     In sterilizing containers equipped with filters, the exchange of media in the sterilizer was intended to take place through these filters. The filters were accordingly designed in such a way that they could compensate sufficiently quickly for the pressure differences which occurred. This entailed a corresponding pore size which, although small enough to protect the container contents from dust and large-volume microorganisms, was unable to guarantee that no microorganisms could get in, particularly extremely small viruses or fungal spores. Thus, in the sterilizing containers equipped with filters, there was, over the course of time, an increasing risk of penetration of microorganisms. 
     SUMMARY OF THE INVENTION 
     The invention is therefore based on the object of making available a sterilizing container equipped with filters, in which the filter has fine pores and is designed in such a way that there is no penetration of microorganisms after sterilization, even after long storage periods, but in which the short-term pressure differences occurring in modern autoclaves can be reduced without damage to filter or container. 
     Thus, according to the invention, in addition to the filter, inlet and outlet valves are provided which are also intended to act during the sterilizing process and do not serve merely as safety valves, and which come into action as soon as the pressure difference from outside to inside or from inside to outside has become so great that the exchange of media through the filter material cannot take place sufficiently quickly. 
     Accordingly, the invention is based on the knowledge that sterilizing containers can be equipped with filters of any desired fineness if care is taken to ensure that a bypass is created in both directions, i.e. not only from outside to inside, but also from inside to outside, when a pressure difference predetermined by the structure is exceeded. 
     According to a preferred embodiment of the invention, filter and valves are arranged in a common container opening, for example in an opening of an intermediate cover, provided with a protective cover, or in a container wall or in the bottom. A particularly expedient and robust construction is obtained if the filter is clamped immovably in a holding frame and at least one of the valves is integrated in the holding frame, which in turn is braced firmly on the opening edge. For the invention, however, the possibility should be left open to arrange the filter and at least one of the valves in different container openings, which can be expedient, for example, if a condensate bleeder valve is to be arranged on the bottom of the sterilizing container. This condensate bleeder valve can then be designed at the same time as an overpressure valve, via which an increased internal pressure in the container can be reduced. 
     The two valves can be integrated in the holding frame of the filter in such a way that there are no outwardly movable parts which could come into contact with the container contents and which could be manipulated from outside. 
     According to the invention, the filter material can have almost any desired flow resistance, and it cannot slip, thus ruling out the danger of an open bypass remaining after completion of the sterilizing process. 
     Compared to the known spring-mounted filter holder plates in which the filter is opened during occurrence of the bypass flow and, on account of the flow, can slip into another position or become stuck, the filter in the arrangement according to the invention always provides correct sealing. According to the invention, the whole arrangement (bypass with filter) is immovable, which results in a dual safety advantage: 
     a) the function of the bypass cannot be blocked by the container contents; 
     b) the bypass cannot be inadvertently actuated by the container contents or from outside. 
     According to the invention, all known filter materials can be used, for example surface filters made of paper, synthetics or textile, and also membrane filters or  3 D volume filters and submicron particulate filters, by which even viruses or fungal spores can be held back. 
     Preferred designs of the filter/valve combination are set out in the dependent claims and in the description of illustrative embodiments. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Illustrative embodiments of the invention are described below with reference to the drawing, in which: 
     FIG. 1 shows a half cross-sectional view of a sterilizing container according to the invention, with a filter leaf with double valve arrangement incorporated in an intermediate cover; 
     FIG. 2 is a sectional view of the intermediate cover according to FIG. 1; 
     FIG. 3 is a view of the filter/valve arrangement according to FIG. 2, seen from above; 
     FIG. 4 is a view of the filter/valve arrangement according to FIG. 2, seen from below; 
     FIG. 5 shows a perspective view of the valve ring enclosing the filter; 
     FIGS. 6 to  9  show a filter/valve combination similar to that in FIGS. 1 to  5 , but in which the upper filter holder plate is formed by the intermediate cover itself; 
     FIG. 6 shows a section along the line VI—VI according to FIG. 7; 
     FIG. 7 is a plan view of FIG. 6; 
     FIG. 8 is a view of FIG. 6 from below, FIG. 9 is a section along the line IX—IX according to FIG. 8; 
     FIG. 10 is a partial sectional view of a sterilizing container which is provided in the intermediate cover with a filter/inlet valve combination and bears the outlet valve in the bottom part; 
     FIG. 11 shows a cross section of a modified embodiment of a filter/valve combination arranged in the intermediate cover; 
     FIG. 12 is a plan view of the filter/valve combination from above, and 
     FIG. 13 is a plan view of the filter/valve combination according to FIG. 11, seen from below; 
     FIG. 14 is a cross section of a further modified embodiment of a filter/valve combination; 
     FIG. 15 is a plan view according to FIG. 14, seen from above; 
     FIG. 16 is a plan view according to FIG. 14, seen from below; 
     FIG. 17 is a sectional view of a further embodiment of a filter/valve combination, sectioned along the line XVII—XVII according to FIG. 18; 
     FIG. 18 is a view of the filter/valve combination according to FIG. 17, seen from above; 
     FIG. 19 is a view of the filter/valve combination according to FIG. 17, seen from below; 
     FIG. 20 is a section along the line XX—XX according to FIG.  18 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In terms of its basic.design, the sterilizing container shown in FIG. 1 corresponds to the sterilizing container according to DE 3,146,349 A1, and it consists of a lower part  10  of the container, an intermediate cover  12 , which is fitted via a sealing ring  14  onto the inwardly directed edge of the lower part of the container, and a closed container cover  16  which engages over the lower part of the container with intermediate cover and leaves a labyrinth gap  18  free for exchange of media during the sterilizing process in the sterilizer. For the purposes of exchange of media, the intermediate cover has a filter/valve combination  20 , which can be seen in detail in FIGS. 2 to  5 . This filter/valve combination  20  in the double cover proves expedient because it is protected by the container cover  16  engaging over it. For the invention, however, the possibility should be left open for accommodating such a filter/valve combination at other points of a sterilizing container, for example in the side walls or, in the bottom or in a cover closing the container. 
     Two valve rings  22 ,  24  are clamped into a circular opening of the intermediate cover  12 , which valve rings  22 ,  24  between them clamp the edge  26  of the opening of the intermediate cover  12 . The two valve rings  22 ,  24  are of identical design, but are offset by 180° in terms of their position and placed in opposite directions (FIG.  5 ). The valve rings could also be made in one piece. The valve rings  22 ,  24  bear a filter holder plate  28  which is provided in the central area with perforation holes  29  for the exchange of media and which on one side, over the valve ring  22 , has an arc-shaped slit  30  and, on the other side, over a semicircle, has holes  32 . From the bottom, the valve ring  22  is supported by an annular frame  34  which is L-shaped in cross section and whose vertical branch is braced with the filter holder plate  28  by screws  36 . The horizontal branch of the annular frame has, on one side under the arc-shaped slit  30 , holes  38 , and, on the other side under the holes  32 , an arc-shaped slit  40 . The valve ring  22  is made of an elastic material and it is clamped sealingly against the edge of the intermediate cover by the screws  36 . At the top and bottom, the valve ring  22  is enclosed from the outside by annular walls  42  which are made integral with the filter holder plate  28  or the annular frame  34 , for example as a cup-shaped drawn part, injection-molded part or rotary part. The vertical branch of the annular frame  34  has an internal thread  44  into which a perforated bracing disk  46  with hand grip  48  can be screwed. A filter disk  50  is clamped sealingly between the filter holder plate  28  and the bracing disk  46 . 
     The valve ring  22  has an annular chamber which is divided by dividing walls  52  into two circular arc-shaped chambers  54  and  56  which extend almost 180° between the dividing walls  52 . In the left-hand circular arc section according to FIG. 2, the valve ring has a lip seal  58  which extends from the outside inward over the chamber  54 , which is prestressed with a predetermined force against the filter holder plate  28  and seals off the holes  32 . In the area of the other arc-shaped chamber  56 , the valve ring  22  has a lip seal  60  which extends from the outside inward and which is prestressed against the horizontal branch of the annular frame  34  and seals off the holes  38 . 
     In this way, the filter disk  50  is fixed immovably relative to the intermediate cover  12  via the holding frame, which is formed by the annular frame  34 , the valve ring  22  and the filter holder plate, and braced via the bracing disk  46 . If, during the sterilizing process, the pressure difference between outside and inside exceeds a value which can no longer be compensated via the filter  50 , the lip seal  58  is then lifted from the filter holder plate  28  so that an exchange of media can take place via the holes  32 , the chamber part  54  and the arc-shaped slit  40 . If, by contrast, during the sterilizing process, the pressure difference between the inside of the sterilizing container and the sterilizer exceeds a predetermined value, the lip seal  60  is then lifted from the holes  38  and a bypass is established via the chamber section  56  and the arc-shaped slit  30 . While the valve arrangement opens and closes again automatically under the elastic prestressing of the lip seals, the filter holder plate remains immovably clamped in position, so that no disturbances can occur if parts of the container contents come into the proximity of the filter. In order to avoid disturbances also in the area of the lip seals  58  and  60 , and to ensure perfect valve functioning even when matter on the inside or outside comes near to the through-openings or slits, these can be bridged for protection. This can be done, for example, by forming bridges across the holes or slits as these are being punched out. 
     According to the illustrative embodiment in FIGS. 6 to  9 , the intermediate cover  12 A is designed as an upper filter holder plate and for this purpose has a perforation  29 A below which the filter disk  50 A is braced. It will be evident from FIGS. 6 and 9 that these can be filters of any type, namely, as sketched on the right-hand side, a thin flat filter, and, as shown on the left-hand half, a thicker, filter, for example a ceramic filter or volume filter. 
     This filter  50 A is braced from below against the intermediate cover  12 A by a filter holder element, and a sealing ring  64  provides a seal between filter  50 A and intermediate cover  12 A on the outer edge. This filter holder plate is fixed on the outer edge of the intermediate cover  12 A in any desired way, for example by clamping or screwing. An important point here is that no cavities remain upon deliberate dismantling (e.g. filter replacement or filter inspection). This ensures excellent cleaning possibilities without wash shadows. The filter holder plate  62  is provided with perforation holes  66 . Arranged all around the filter disk  50 A, between the intermediate cover  12 A and the filter holder plate  62 , there is an annular chamber  68  in which a valve ring  70  is braced between intermediate cover  12 A and filter holder;plate  62 . Two diametrically opposite dividing walls  72  of the valve ring  70  divide the annular chamber  68  into two circular arc sections. In the arc chamber on the left-hand side according to FIGS. 6 to  8 , the valve ring  70  bears sealing lips  74  which are prestressed against the intermediate cover  12 A and close off the opening  76  of the intermediate cover arranged in this area. On the right-hand side according to FIGS. 6 to  8 , the valve ring  70  has sealing lips  78  which are prestressed down toward the filter holder plate  62  and which cover the openings  80  in this arc section. Under the openings  76 , the filter holder plate  62  has openings  82  via which an exchange of media can take place if an external overpressure develops, after the sealing lips  74  are lifted from the openings  76 . Over the openings  80 , the intermediate cover  12 A has openings  84  via which the exchange of media can take place if the sealing lip  78  is lifted from the openings  80  by internal overpressure. 
     FIG. 10 shows the cross-sectional view of a sterilizing container in which a filter/inlet valve combination is arranged in the intermediate cover  12 A. This combination essentially corresponds to the structure according to FIGS. 6 to  9 , with the difference that a continuous, undivided annular chamber  68 B is provided and the valve ring  70 B is of continuous design, as is illustrated in FIG. 6 for the left annular chamber. That is to say, its sealing lips  74 B bear on the intermediate cover  12 A over the entire circular arc area and close the openings  76 B of the intermediate cover  12 A. If an external overpressure develops, the sealing lip  74 B lifts from the intermediate cover and the route between the openings  76 B and the openings  82 B. 
     In this illustrative embodiment according to FIG. 10, the bottom  86  of the lower part  10  of the container is provided with an upwardly convex curvature and the bottom edge is beveled off downward so as to give a recessed annular channel which is provided with outlet openings  88 . Bearing against these outlet openings  88  from below is the sealing lip  90  of a valve ring  92 , which sealing lip  90  lifts in the event of a predetermined pressure difference developing, and thus allows air/vapor to flow out and at the same time permits escape of condensation water which has accumulated in the annular channel. The valve ring  92  is clamped in a stand frame  94 . This arrangement affords advantages, particularly with the filter provided for the invention, because the water above the valve is then forced out first. The ensuing strong downward/outward flow then entrains isolated, remaining droplets with it and thus permits complete drying upon steam sterilization. 
     In the illustrative embodiment according to FIGS. 11 to  13 , a valve ring  22 A is pushed with its outer annular groove  24  onto the edge  26  of the opening of the intermediate cover  12 . This valve ring  22 A is clamped between an upper filter holder plate  28 A and a lower annular frame  34 A, which corresponds to the annular frame  34  according to FIG.  2 . The filter holder plate  28 A is joined via screws  36  to the vertical branch of the annular frame  34 . The vertical branch of the annular frame  34 A has, in the central section, a rib  96  of triangular cross section. This rib  96  acts as a valve seat for a sealing lip  98  which protrudes inward from the valve ring  22 A over the entire periphery. The sealing lip  98  is designed as a continuous annular lip and is situated in an annular chamber  100  between the valve ring  22 A and the vertical branch of the annular frame  34 A. The filter holder plate has openings  102  above the annular chamber  100 , and the horizontal branch of the frame  34 A has openings  104 . As in the illustrative embodiment according to FIG. 2, a perforated bracing disk  46  is screwed into the frame  34 A and braces the filter disk  50  against the filter holder plate. In the position shown in FIG. 11, the sealing ring lip  98  bears sealingly on the valve seat, i.e. the rib  96 , from above. When a predetermined pressure difference occurs, with an internal pressure which has increased relative to the external pressure, the sealing lip  98  is lifted and frees the bypass flow path from the openings  104  to the openings  102 . If a predetermined pressure difference builds up in the opposite direction, the lip  98  slips past the rib and opens the flow path from the openings  102  to the openings  104 . If this overpressure is then reduced, the sealing lip  98  bears from below on the rib  96 , on account of its elasticity, and provides a closure which is tight to microorganisms. 
     In this illustrative embodiment too, there are no moving parts except for the sealing lip inside the annular chamber  100 , which is enclosed all around, since the filter/valve combination is braced immovably on the intermediate cover  12 . Of course, this filter/valve combination could also be arranged in a side wall of the container or in a cover placed sealingly on the lower part of the container. 
     A further illustrative embodiment is shown in FIGS. 14 to  16 . Here, the upper filter holder plate  28 B is supported at the periphery on a sealing ring  106  which is made of soft rubber or foamed porous material and which bears on the opening edge of the intermediate cover  12 . As in the illustrative embodiment according to FIGS. 2 and 11, the filter holder plate is screwed to an annular frame  34 B, into which a perforated bracing disk  46  is screwed in turn. The horizontal branch of the annular frame  34 B bears a sealing ring  108  braced from below against the edge of the intermediate cover  12 , with an inwardly directed sealing lip  110  which covers the openings  112  of the bracing disk  46  in the rest state. 
     If, during the sterilizing process, the external pressure builds up relative to the internal pressure, the sealing ring  28 B is squeezed together when a predetermined pressure difference is reached, and the annular frame. 34  is pressed down with the filter holder plate, as a result of which the sealing ring  108  is lifted from the opening edge of the intermediate cover  12 , so that a bypass is created via the openings  102  in the filter holder plate and the annular opening above the sealing ring  108 . When a pressure difference occurs in the opposite direction, the sealing lip  110  is lifted from the openings  112 , and a bypass is created in the opposite direction via the openings  102 . Although the whole filter structure with holding frame moves here in the event of an external overpressure, suitable coverings can be used to prevent the container contents from disturbing or blocking the function of the valve arrangement. 
     FIGS. 17 to  20  show a further illustrative embodiment. Here, a sealing ring  114  of soft rubber with an outer annular groove is pushed onto the edge of a cover opening of the intermediate cover  12 . The edge of the filter holder plate  28  lies on the sealing ring  114 . Bearing from below against the sealing ring  114  is the horizontal branch of the annular frame  34 , into which the bracing disk  46  is screwed, pressing the filter disk  50  against the filter holder plate. Arranged between the sealing ring  114  and the annular frame  34  there are two circular arc-shaped chambers  54  and  56  which are sealed off from one another by inwardly extending dividing walls  116  of the sealing ring  114 . The chamber  56  communicates with the outside via openings  118  in the filter holder disk  28 , and the chamber  54  communicates with the inside of the container via openings  120  in the bracing disk  46 . 
     In the event of an external overpressure, the upper part of the sealing ring  114  is squeezed together, and the horizontal branch of the annular frame  34  is lifted from this sealing ring, as a result of which a bypass is created via the openings  118 . Conversely, in the event of an overpressure from the inside, the underside of the sealing ring  114  is squeezed together, as a result of which the filter holder plate is lifted with its edge from the sealing ring and frees a bypass via the openings  120 . 
     The sterilizing container according to the invention is suitable not only for steam sterilization, but also for sterilization by gas or plasma. By means of the sterilizing container according to the invention, a sterilized condition is preserved until intentional opening of the container, since by using the invention—and without hindering sterilization—substantially better, denser filters can be used. 
     The invention can be used not only for clinical sterile material, but also for any other items to be sterilized, for example in the pharmaceutical industry. 
     To protect the through-openings and to prevent matter from penetrating into the openings and impairing the function of the valves, a protective covering can be provided, which protective covering can be obtained by bridging the holes as they are being punched out. 
     The preferred embodiment is the circular design, but rectangular filter/valve combinations are also possible.