Abstract:
The invention relates to a sterile container, in particular for the receipt and sterile storage of surgical instruments or material, comprising a receiving chamber and a gas exchange opening that can be sealed using a sterile filter. The aim of the invention is to prevent undesired liquid from reaching the sterile filter. To achieve this, the exterior of the lid is provided with at least one inflow edge, which faces away from the gas exchange opening, and falls away towards the exterior in relation to a lid plane.

Description:
This application is a continuation of international application number PCT/EP02/09749 filed on Aug. 31, 2002. 
     This application claims the benefit of German Patent Application No. 101 56 935.1 filed Nov. 15, 2001. 
    
    
     BACKGROUND OF THE INVENTION 
     The invention relates to a sterile container, in particular for the holding and sterile storage of surgical instruments or material, comprising a holding space, which is defined by a container base and container walls, a lid for closing the holding space and a gas exchange opening, which can be closed off by a sterile filter. 
     Sterile containers of the type described in the introduction, once they have been filled, for example with surgical instruments and/or material, are sterilized in a sterilizer using steam or other media. Consequently, the problem frequently arises whereby the lid, after the sterilizing operation, is wetted with liquid, in particular with residual condensate. This can then reach the sterile filter in an undesired manner. The same problem arises if the sterile container is inadvertently exposed to any liquid. 
     Therefore, it is an object of the present invention to improve a sterile container of the type described in the introduction in such a manner that it is impossible for any liquid to reach the sterile filter in an undesired manner. 
     SUMMARY OF THE INVENTION 
     According to the invention, this object is achieved by virtue of the fact that on the outer side of the lid there is provided at least one inflow edge which faces away from the gas exchange opening and slopes downward toward the outside relative to a lid plane. 
     This configuration allows gas or steam to flow along the inflow edge to the gas exchange opening and through the latter into the holding space, or vice versa. By contrast, a liquid which reaches the lid can flow off away from the gas exchange opening. This prevents water from accumulating on the lid, and consequently there is no risk of liquid being able to flow onto the sterile filter. 
     To ensure that the liquid can flow off reliably and under all conditions, it is advantageous if an angle of inclination which is included by the inflow edge and the lid plane is at least 1°. 
     There is advantageously provided a protective element which covers the sterile filter at a spacing therefrom. This protects the sterile filter from mechanical loads and from being acted on by liquid; a protective element which curves convexly away from the lid has proven advantageous with a view to avoiding accumulations of liquid on the protective element. 
     To make it easier for liquid which is present on the protective element to flow away, it is expedient if the protective element is disposed on an outer side of the sterile container. 
     According to a preferred embodiment of the invention, it is possible to provide that the lid, on its outer side, has a seating surface for seating the protective element, which surrounds the gas exchange opening. This allows the protective element to be attached or connected to the lid in a defined way. Furthermore, it advantageously fits into the lid, for example in order to form a common surface. 
     To ensure as flat an overall shape as possible, it is advantageous if the seating surface comprises an annular surface which runs parallel to the lid plane and is set back in the direction of the holding space. 
     To ensure that it is impossible for any liquid to reach the sterile filter in an undesired way, it is advantageous if the protective element completely covers the gas exchange opening and the seating surface. Liquid which is present on the protective element can then flow off the protective element without reaching the seating surface surrounding the gas exchange opening or the sterile filter covering the gas exchange opening. 
     It is preferably possible for there to be provided support surfaces for the purpose of supporting the protective element connected to the lid. The protective element is supported on the lid via these support surfaces. 
     To ensure that a defined spacing can be maintained between the protective element and the lid, it is preferable for the protective element to comprise spacer elements. 
     It is expedient if the protective element comprises a reinforcing frame. In particular in the case of protective elements made from soft or elastic materials, or also in the event of exposure to hot steam, the protective element is stabilized in its desired shape by the reinforcing frame. 
     It is particularly advantageous if the reinforcing frame comprises webs which cross one another and run substantially parallel to the lid surface. A reinforcing frame of this type can be produced particularly easily and offers sufficient stability while consuming only minimal material. 
     To keep the structural outlay and number of components of the sterile container small, it is expedient if the spacing elements are formed by projections and/or at least in part by the webs. Therefore, the projections and/or webs fulfil a dual function. Firstly, they reinforce the protective element, and secondly they ensure a desired spacing between the protective element and the lid. 
     To facilitate assembly of the sterile container and to increase the ease of maintenance, in a preferred embodiment of the invention there is provided at least one snap-action connection for connecting the protective element to the lid. 
     A further advantage ensues if the at least one snap-action connection is provided for connection of the protective element to a rim, which includes latching recesses, of the gas exchange opening. In particular in the case of protective elements which are not of rotationally symmetrical configuration, it is in this way possible to achieve a defined positioning of the protective element on the lid. The snap-action connection makes it easy to connect the protective element to the lid and release it again from the latter. 
     A particularly compact overall shape of the sterile container results if the at least one snap-action connection comprises elastic spring arms which project away from the protective element toward the lid and are provided with a latching projection. Moreover, it is in this way easy for the protective elements to be clipped to the lid, for example to the rim of the gas exchange opening. 
     The protective element itself could be provided with openings in order to allow gas exchange with the filter unit through the protective element to the gas exchange opening. However, it is particularly advantageous if there is provided, between the protective element and the lid, at least one opening for the passage of gas, which is in fluid communication with the gas exchange opening. This means that there is no need for any additional perforation in the protective element. The opening for the passage of gas is formed solely by the corresponding shape of the protective element and of the lid. Liquid which is present on the protective element can completely flow off the protective element without further covering of apertures in the protective element. 
     To additionally suppress penetration of liquid onto the sterile filter, it is advantageous if the opening for the passage of gas is arranged in such a way that it becomes possible for gas to flow in a direction of flow running substantially transversely with respect to the flow-permitting direction through the sterile filter. 
     A particularly flat overall shape results if the opening for the passage of gas, in cross section, has a double-convex lens shape. Furthermore, a run-off channel for liquids is formed by the lid surface, which is curved concavely in order to form the double-convex lens shape. 
     To allow gas exchange through the gas exchange opening with stacked sterile containers, it is expedient if the lid has at least one spacer element for stacking a further sterile container on the sterile container. 
     It is preferable for the inflow edge to be disposed between two spacer elements. This allows sufficient inclination of the inflow edge to enable liquid which has reached the lid to flow off. 
     To enable a plurality of sterile containers to be stacked safely on top of one another, it is expedient if the spacer elements comprise at least three projections facing away from the outer side of the sterile container. 
     In an advantageous embodiment of the invention, it is possible to provide that the seating surface is delimited by the at least one inflow edge and the at least one spacer element. This enables liquid to flow from the spacer element onto the inflow edge and then to be directly discharged from the latter. 
     To enable the protective element to be fitted into the lid surface without free edges being visible in the transition between the protective element and the lid, it is expedient if the spacer elements comprise or adjoin the support surfaces. 
     The sterile container can be produced particularly easily and inexpensively if the lid, the at least one spacer element, the seating surface and the at least one inflow edge are formed integrally. 
     To further simplify construction of the sterile container, it is advantageous if there is provided a filter unit, which comprises the sterile filter, a carrier and a holding element, and if the sterile filter is held between the carrier and the holding element. 
     The filter unit can be exchanged particularly easily, thereby increasing ease of maintenance of the sterile container, if the filter unit is in single-piece form, and if the carrier, the sterile filter and the holding element are nonreleasably connected, in particular by welding or adhesive bonding, to one another. 
     In a further preferred embodiment of the invention, it is possible to provide that the filter unit is mounted moveably, that the filter unit, in a closed position, closes a flow path and, in a flow-permitting position, opens the flow path, so that gas exchange in the closed position is possible only through the sterile filter and in the flow-permitting position is possible through the sterile filter and/or through the flow path. This means that the filter unit can be transferred into the closed position or the flow-permitting position on demand, depending on the level of gas and/or steam throughput which is desired. 
     To avoid damage to the sterile container and to simplify its overall structure, it is advantageous if there is provided a pressure-relief valve, if the pressure-relief valve is disposed in such a way that in a basic position it adopts a closed position, if it adopts a flow-permitting position when a pressure in a vicinity of the sterile container exceeds a pressure in the sterile container by a predetermined pressure difference, and if the pressure-relief valve forms the filter unit. The filter unit therefore serves firstly as a filter and secondly as a pressure-relief valve. Therefore, separate provision of a pressure-relief valve is no longer required. 
     To increase the stability of the lid, which is advantageous in particular in the case of large gas exchange openings, the gas exchange opening comprises at least one stiffening element for stiffening the lid. This can be achieved, for example, by webs or carriers which span the gas exchange opening. 
     It is preferable for the at least one stiffening element to be formed by a web spans the gas exchange opening. This web simultaneously serves as additional protection for the sterile filter. 
     In principle, the stiffening element could adjoin the seating surface, which runs parallel to the lid plane and is set back toward the holding space, and could therefore likewise be set back toward the holding space. However, it is expedient if the at least one stiffening element is offset in a direction away from the holding space relative to the outer side of the lid. This enables the condensed fluid which forms on the stiffening element to flow away from the stiffening element without reaching the sterile filter through the gas exchange opening. 
     To provide the sterile filter with even better protection against the penetration of fluids, in a preferred embodiment of the invention it is provided that there is a fluid-retaining element for preventing fluid from flowing in from the outer side of the lid through the gas exchange opening. This prevents any form of fluids, in particular including condensate, from being able to reach the sterile filter. 
     In principle, the fluid-retaining element could be disposed on an inner side of the lid. However, it is advantageous if the fluid-retaining element is disposed on the outer side of the lid and surrounds the gas exchange opening at least in sections. This right from the outset prevents fluids from being able to reach the region of the gas exchange opening. 
     In principle, the fluid-retaining element could also be formed by a membrane which spans the gas exchange opening. However, better gas exchange can be achieved if, in a preferred embodiment of the invention, the fluid-retaining element is formed as a rim which protrudes from the outer side of the lid. Moreover, a rim of this type can be produced particularly easily and inexpensively. 
     To keep fluids as far away from the gas exchange opening as possible, it is expedient if the fluid-retaining element is disposed at a spacing from the gas exchange opening. Furthermore, the region which adjoins the gas exchange opening and is protected from the penetration of fluids can serve, for example, as a seating surface. 
     It is preferable for the protective element to completely cover the gas exchange opening and the fluid-retaining element. Consequently, fluids which flow off the protective element must first overcome the fluid-retaining element before they are able to reach the sterile filter through the gas exchange opening. 
     The sterile container can be produced particularly easily and favorably if the lid is made from a plastic, in particular from polyether ether ketone (PEEK) or polyphenyl sulfone (PPSU). 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The following description of a preferred embodiment of the invention, in conjunction with the drawing, serves to provide a more detailed explanation. In the drawing: 
         FIG. 1  shows a perspective overall view of a sterile container; 
         FIG. 2  shows a plan view of an excerpt of a sterile container; 
         FIG. 3  shows an exploded view of an excerpt of a lid of the sterile container; 
         FIG. 4  shows a partially cut-away cross-sectional view through an excerpt of a lid; 
         FIG. 5  shows a partially cut-away side view of an excerpt of a lid; 
         FIG. 6  shows an enlarged, perspective partial view of a lid; 
         FIG. 7  shows a view onto the underside of half of a lid; 
         FIG. 8  shows a cross-sectional view of an excerpt of a filter cartridge which is mounted in a gastight manner on the lid; 
         FIG. 9  shows a cross-sectional view of an excerpt similar to that shown in  FIG. 8 , with a filter cartridge lifted off; 
         FIG. 10  shows a plan view of an excerpt of an alternative configuration of a lid; and 
         FIG. 11  shows a cross-sectional view  11 — 11  of an excerpt from  FIG. 10 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  illustrates a sterile container, which is denoted overall by reference numeral  10  and comprises a substantially tub-like, cuboidal container  12  for holding, for example, surgical instruments or material, and a lid  14 . Pivotably mounted carry handles  16  are disposed at the end faces of the container  12 . 
     The structure of the lid  14  is explained in more detail with reference to  FIGS. 2 to 9 . 
     The lid  14  is provided with an encircling rim  18  which projects perpendicularly from a lid plane  15 , so that the lid  14  completely covers and partially engages around the container  12 . A sealing rim  20 , between which and the rim  18  a seal (not shown) can be inserted, runs parallel to and at a spacing from the rim  18 . When the lid  14  has been fitted, the sealing rim  20  is located inside the container  12 . The seal makes it possible to produce a gastight connection between the lid  14  and the container  12 . 
     At its narrow end sides, the lid  14  in each case has a bearing bracket  22 , on which a resilient closure flap  24  can pivot about a pivot axis running parallel to a pivot axis of the carry handle  16  when the lid  14  is seated on the container  12 . 
     The lid  14  has two symmetrically disposed circular openings  26 , which have an opening rim  28  which faces parallel to the lid plane  15  and on which four webs  30 , which run perpendicularly toward one another and meet in the center of the opening  26 , for stiffening the lid, are disposed symmetrically. Between each pair of webs  30  disposed at the opening rim  28 , two indentations  32  and  33  are cut symmetrically into the opening rim  28 . 
     The opening  26  is surrounded by an annular surface  34 , which runs parallel to the lid plane  15  but is set back toward an underside  36  of the lid. As a result, an inner annular edge  38  is formed on a top side  37  of the lid and an outer annular edge  39  is formed on the underside  36  of the lid. The annular edge  38  is adjoined by four inflow edges  40  and four support surfaces  42  which alternate with one another. The inflow edges  40  are curved concavely away from the lid top side  37  and are inclined outward, so that an inclined plane with an angle of inclination  44  between the inflow edge  40  and the lid plane  15  of approximately 2° is formed. 
     The support surfaces  42  run parallel to the lid plane  15  and, when seen in plan view, are approximately in the shape of a trapezoid, but in each case with concavely curved base edges. The longer of the two base lines of the support surface  42  is adjoined by a three-sided pyramid  46 , which has a base area which is substantially in the shape of an isosceles right-angled triangle. An apex  48  of the pyramid lies just above the base sides, which intersect at right angles, of the base surface, slightly offset toward the opening  26 . 
     This results in the formation of a run-off surface  50  which is approximately in the shape of an isosceles, right-angled triangle which is inclined toward the support surface  42 . The support surface  42  is offset away from the lid top side  37 , parallel to the lid plane  15 . 
     The overall result, therefore, is an approximately square structure on the lid  14 , which is formed by four pyramids  46 , which are each seated in the corners of the square, the side faces of the square running parallel to sides of the lid  14 . The inflow edges  40  are therefore inclined perpendicularly toward the sides of the lid  14 . The structure has a total of two planes of symmetry running parallel to the sides of the lid  14 . On its side facing away from the opening  26 , the inflow edge  40  extends down to the level of the lid plane  15 . When the lid is seen from the side, therefore, the result is approximately a concave shape, facing away from the lid top side  37 , from the apex  48  of the pyramid  46  in a corner of the square structure to the apex  48  of the pyramid  46  in an adjacent corner of the structure. 
     Adjacent to the indentations  32  and  33  are disposed a total of four hollow-cylindrical, open sleeves  52  protruding from the underside  36  of the lid. A filter cartridge  54  is mounted resiliently on these sleeves. The filter cartridge comprises an approximately octagonal filter holder  58 , which is provided with a carrier rim  56  and has an annular filter receiver  60  for accommodating a circular long-term filter  62 . An annular recess  64 , which is configured with a larger diameter than the filter receiver  60 , is used to accommodate a holding ring  66 , which in cross-section has an L-shaped profile, one limb of which presses the long-term filter  62  into the filter receiver  60  and the other limb of which engages against the recess  64 . The holding ring  66  is provided with an annular ring groove, which in cross-section includes slightly more than half of a circle, for accommodating a sealing ring  70 . 
     Four mounting sleeves  74 , corresponding to the sleeves  52  disposed on the lid  14 , protrude from a filter holder base  72  toward the lid; these mounting sleeves are open from the filter holder base  72 , and their other, closed end face  76  is provided with a central through opening  78  whose diameter corresponds to that of the sleeve  52 . To mount the filter cartridge  54 , the four mounting sleeves  74  are pushed over the sleeves  52 , a coil spring  80  is in each case fitted over the sleeves  52 , and then the mounting sleeves  74  of the filter holder base  72  are closed off with a stopper  82  which has a disk-like head  84  whose external diameter is matched to the internal diameter of the mounting sleeves  74 . On account of the fact that the coil spring  80  is supported against the head  84  of the stopper  82 , it presses the end face  76  onto the underside  36  of the lid. 
     The filter holder base  72  is provided with a total of twenty strip-like slots  86  of different lengths, with in each case five slots running parallel to one another and approximately covering the area of a quarter-circle. Slots  86  belonging to adjacent quarter-circles are in each case positioned perpendicular to one another. A protective web  88  is formed between each pair of slots  86 . A strip  90 , which faces away from the filter holder base  72  and from which, once again running parallel to the filter holder base  72 , there protrudes a support web  92  facing away from the associated protective web  88  and in each case completely covering a slot  86 , is disposed on each protective web  88 . All the support webs  92  define a common plane on which the long-term filter  62  rests. Overall, the filter receiver  60  and the support webs  92  form a carrier support for supporting the long-term filter  62 . 
     The filter holder  58 , the long-term filter  62  and the holding ring  66  are fixedly connected to one another, for example by welding or adhesive bonding. In the assembled state, the coil springs  88  press the filter cartridge  54  onto the underside  36  of the lid, with the filter cartridge  54  being sealed against the underside  36  of the lid by means of the sealing ring  70 . 
     The holding ring  66  has an outer ring and an inner ring  94  running concentrically therewith, from which four holding ring webs  96  disposed radially and symmetrically stabilize the holding ring  66 . 
     On account of the offset arrangement of support web  92  and protective web  88 , the long-term filter  62  supported on the support webs  92  is protected from direct mechanical damage. However, the long-term filter  62  is virtually unprotected on its side facing toward the opening  26 . For this purpose, a protective cover  98 , which is of mirror-symmetrical configuration and has a cover surface  100  curved convexly away from the top side  37  of the cover, is provided as a protective element; when the cover surface  100  is seen in plan view, it is in the shape of a non-equilateral octagon with short sides  102  and long sides  104 . 
     An annular strip  108 , which comprises four cutouts  110 , each disposed diametrically in pairs, protrudes from an underside  106  of the protective cover. These cutouts  110  are shaped in such a manner that they can engage over the webs  30  and the protective cover  98  rests on the webs  30 . Two spacer strips  112 , which cross one another, are disposed on the underside  106  of the protective cover, as additional spacers, which spacer strips, in the region of the cutouts  110 , project outward beyond the ring strip  108  as far as the long sides  104 . When the protective cover  98  has been fitted, these strips rest on the annular surface  34 . 
     To secure the protective cover  98  there are four latching connectors  114 , which each comprise three limbs, which are disposed at right angles to one another, form a U-shaped frame  116  and two of which protrude radially outward from the ring strip  108 . As free ends of the spacer strips  112 , they form spacers resting on the annular surface  34 . From a transverse web  118  of the frame  116 , two latching arms  120  protrude parallel and at right angles from the underside  106  of the protective cover, which latching arms are provided at their free ends with a latching lug  122  protruding at right angles. The four latching connectors  114  are disposed in diametrically opposite pairs on the protective cover  98 . 
     To secure the protective cover  98 , the latter is moved perpendicularly toward the top side  37  of the lid and is oriented in such a way that the cutouts  110  each face toward a web  30  and the latching arms  120  each slide into one of the two indentations  32  and  33 . As soon as the cutouts  110  rest on the webs  30 , the closure strips  112  and the frames  116  rest on the annular surface  34 , the latching arms  120  latch to the opening rim  28  as a result of the latching lugs  122  engaging behind the opening rim  28 . 
     The size of the protective cover  98  is selected to be such that in the inserted position the annular surface  34  is completely covered. The short sides  102  then rest on the support surfaces  42 , while the long sides  104  run parallel to the side edges of the lid  14  and in each case partially cover the inflow edges  40 . When the protective cover  98  is inserted, the long-term filter  62  held in the filter cartridge  54  is also completely protected from mechanical damage from its other side. 
     In an alternative variant of a lid, which is indicated by dot-dashed lines in  FIG. 2 , the long sides  104  of the protective cover  98  are lengthened. The pyramid  46  then has, in its run-off surface  50 , an additional recess, in which the short side  102  of the protective cover  98  is fitted. This results in a seamless transition between the run-off surface  50  and the cover surface  100 . 
     The highest point of the protective cover  98  when the latter is inserted lies beneath the highest point of the four pyramids  46 , so that when sterile containers  10  are stacked on top of one another the container  12  which is mounted on the lid  14  rests only on the apexes  48  of the pyramids  46  but does not touch the protective covers  98 . 
     If, with a substantially horizontally mounted sterile container  10 , liquid reaches the top side  37  of the lid, for example reaches the protective cover  98 , the curvature of the protective cover  98  means that the liquid can flow off to the short or long sides  102  or  104 , respectively. From the long sides  104 , the liquid passes onto the inflow edges  40 , from which the liquid can flow off to the sides of the lid  14  on account of the inclination of these edges. 
     When the protective cover  98  is fitted, a substantially double-convex lens-shaped inflow opening  124 , as seen in side view, is formed, through which a gaseous fluid can flow in and out. The fluid then flows substantially parallel to the lid plane  15 , through the opening  26  substantially perpendicular thereto. In a basic position illustrated in  FIG. 8 , the filter cartridge  54  engages against the underside  36  of the lid, sealed off by means of the sealing ring  70 . If the sterile container  10  is exposed to hot steam, the latter flows to the long-term filter  62 , as described above. It passes through the long-term filter  62  and then follows a flow channel, defined by the support web  92 , the strip  90  and the protective web  88 , into the interior of the container  12 . 
     If a pressure acting from outside on the sterile container  10  exceeds a force which can be set by means of the coil springs  80 , the filter cartridge  54 , which is mounted resiliently on the lid  14 , acts as a pressure-relief valve. The filter cartridge  54  is lifted off the underside  36  of the lid and opens up a flow channel  126  which is closed in the basic position, as illustrated in  FIG. 9 . Hot steam can now pass not only through the long-term filter  62  but also into the interior of the container  12  via the flow channel  126 . As soon as the pressure gradient drops again, the coil springs  80  press the filter cartridge  54  back onto the underside of the lid, so that steam or gas can only flow in and out via the long-term filter  62 .  FIGS. 8 and 9  use arrows to indicate the incoming and outgoing flow of a gas or steam. 
     A slightly modified variant of the lid  14   a  will now be explained in more detail with reference to  FIGS. 10 and 11 . 
     In a lid  14  as has been explained in connection with  FIGS. 1 to 9 , it is possible to provide, as an additional element, a fluid-retaining element in the form of an encircling edge  130 . The encircling edge  130  is formed as an annular projection which protrudes from the top side  37  of the lid and surrounds the opening  26  on the top side  37  of the lid. In the exemplary embodiment illustrated, the edge adjoins the annular edge  38  on the outer side toward the inflow edge  40 , with a short spacing between them. Alternatively, however, it would also be conceivable for the edge  130  to directly adjoin the opening rim  28  or the annular edge  38 . If the gas exchange openings in the lid  14  are not circular in form, it is preferable for the edge  130  to follow the contour of the opening. The long side  104  of the protective cover  98  projects beyond the edge  130 , so that liquid which runs off the protective cover  98  drops directly onto the inflow edge  40  but cannot pass over the edge  130 , which forms a barrier, through the opening  26  and onto the long-term filter  62 . Furthermore, the webs  30   a  are offset away from the opening  26  and the top side  37  of the lid, so that, unlike in the case of the lid  14  described in connection with  FIGS. 1 to 9 , a set-back annular surface  34  is not formed. 
     The container  12  may optionally be made from metal or plastic. The lid  14  is preferably made completely from a plastic, for example from polyether ether ketone or polyphenylene sulfone. The long-term filter is preferably made from polytetrafluorethylene.