Abstract:
The invention relates to a sealing cap ( 11 ), for openings and containers. The valve arrangement ( 15 ) comprises an axiallly displaceable valve body ( 17 ), which is held in the direction of the container interior by means of a spring ( 22 ) against a first sealing seat ( 34 ), on the cap interior. The valve arrangement ( 15 ) comprises one single valve body ( 17 ), provided with a first axially effective sealing surface arrangement ( 20 ) and a second radially effective sealing surface arrangement ( 21 ). The axially effective sealing surface arrangement ( 20 ) co-ordinates with an axial seal seat ( 34 ), surrounding a defined opening ( 32 ), connecting to the container interior on the cap inner part ( 14 ). The radially effective sealing surface arrangement ( 21 ) co-ordinates with a first radial counter sealing surface ( 61, 62 ), comprising a bypass ( 39 ), for the first flow connection and a second radial counter sealing surface ( 61 ), comprising a safety relief opening ( 69 ), for the second flow connection.

Description:
FIELD OF THE INVENTION 
   The present invention relates to a sealing cap for openings of containers, especially of motor-vehicle radiators. 
   BACKGROUND ART 
   In one such sealing cap, known from German Patent Disclosure DE 197 53 592 A1, the valve arrangement has two valve bodies, of which, in the position of repose, the first valve body rests directly on a sealing seat of an inner cap part under spring loading, and the second valve body is pressed against a further compression spring by the spring-loaded first valve body. The two-stage opening and closing of the flow connections is achieved by providing that the first valve body is lifted by means of the second valve body from its sealing seat on the inner cap part if the first limit value is exceeded; that when the second limit value is reached, the second valve body presses against a further sealing seat of the inner cap part and thus closes the first flow connection again; and that for the safety stage, an intermediate valve body disposed between the first and second valve bodies lifts with its sealing seat from a sealing face of the second valve body. 
   In terms of its valve arrangement, a sealing cap of this kind is complicated structurally, in terms of production, and in terms of assembly because of the many components. 
   From German Patent DE 41 07 525 C1, a sealing cap is also known that provides for a two-stage pressure equalization of the close container that may become necessary. In this sealing cap, the valve arrangement also has two valve bodies, which are internested in one another; the second valve body is pressed against a sealing seat on the inner cap part by the spring loading of the first valve body. In this arrangement, when the first limit value of the internal container pressure is exceeded, the second valve body lifts, carrying the first valve body with it, from its sealing seat on the inner cap part, and when the second limit value is reached presses against an opposed sealing face of the inner cap part again. In the safety stage, the first valve body is lifted from the second valve body. 
   In the valve arrangement of this known sealing cap, the same disadvantages arise as in the sealing cap described earlier above, and furthermore there is the problem that the sealing seats and sealing faces of the two valve bodies and of the inner cap part, along with the axial travel of the second valve body, must be adapted to one another within narrow tolerances. 
   From German Patent Disclosure DE 197 32 885 A1, a sealing cap with safety locking for openings of containers is also known. This safety locking makes it possible, when overpressure prevails in the container, to prevent the sealing cap from coming unscrewed, specifically by providing that the sealing cap is blocked nonrotatably relative to the fill nozzle on the container. This known safety locking uses an axially movable insert, which surrounds the inner cap part or its valve arrangement and is as a result exposed directly to the overpressure prevailing in the container, because its inner bottom is located in the opening of the fill nozzle. This axially movable insert is axially movable but is retained nonrotatably in a tubular supplementary inner part which is seated nonrotatably in the fill nozzle of the container and relative to which the sealing cap is rotatable. When overpressure occurs in the container, the insert is moved axially in the direction of the sealing cap and engages it nonrotatably. The result is a blockage of rotation of the sealing cap via the insert and the supplementary inner part with the fill opening of the container. 
   The provisions in this reference for torsion prevention or safety locking are complicated both structurally and because of the number of components to be used. Moreover, the axially movable insert and the tubular supplementary inner part not only increase the diameter of the inner cap part of the sealing cap but also reduce the effective area of the valve arrangement of the sealing cap, with adverse effects on the response behavior of the valve arrangement. 
   SUMMARY OF THE INVENTION 
   It is therefore the object of the present invention to provide a sealing cap of the type defined at the outset whose valve arrangement is simplified structurally and in terms of production and assembly. 
   For attaining this object in a sealing cap of the type defined above, wherein the valve arrangement has a single valve body which is provided with a first, axially effective sealing face arrangement and a second, radially effective sealing face arrangement. The axially effective sealing face arrangement has an axial sealing seat surrounding a connection opening to the container interior at the inner cap part, and the radially effective sealing face arrangement has a first radical counterpart sealing face, having a bypass around the first flow connection and the second radical counterpart sealing face having a safety relief opening of the second flow connection. 
   By means of the provisions of the invention, it is attained that considerably fewer components are needed for the valve arrangement of the sealing cap without having to accept disadvantages in terms of the two-stage action upon pressure equalization. Moreover, special provisions for tolerance-bound adaptation become unnecessary. The individual components are structurally simpler and can be produced and put together more economically. 
   In a preferred exemplary embodiment, the axially effective sealing face arrangement and the radially effective sealing face arrangement of the valve body are united in a profiled sealing ring, so that a single sealing element suffices. 
   An advantageous feature of the axial sealing seat is characterized in that the axial sealing seat on the inner cap part is formed by an annular attachment which protrudes from the bottom that is provided with the connection opening. 
   The first radial counterpart sealing face is formed by the inner wall of the inner cap part, in which wall, in a first axial region, an annular insert is received, which forms a bypass around the first flow connection. With these characteristics, an advantageous feature of the first radial counterpart sealing face is attained in such a way that the inner wall of the inner cap part is immediately available for this purpose. By embodying the bypass as a U-shaped throttling conduct on at least one circumferential point of the inner cap part, and by providing two radial conduits in the annular insert disposed in axial spacing, which are formed by an axial conduit between the outer face of the annular insert and the inner face of the inner cap part, it is attained that the closure of the flow connection in the region of the bypass is accomplished primarily by the presence of liquid coolant, rather than by the elevated gas pressure, because whenever liquid coolant is present at the inlet to the bypass, a head pressure builds up that moves the valve body farther in the axial direction, thus preventing an ejection of liquid coolant. In other words, upon an increase in the internal container pressure, the air cushion located above the liquid coolant can escape in this way and contribute to a pressure equilibrium until such time as it has been reduced and the liquid coolant is present. 
   An advantageous feature of the radially effective sealing face arrangement lies in the sealing face arrangement having two sealing face regions whose axial spacing is less than the axial spacing of the two radial conduits of the bypass, and/or, the sealing face regions being formed by a circumferential clearance in the profiled sealing ring, or in that the second radial counterpart sealing face is formed by the inner wall of the inner cap part, in which the safety relief openings are formed in a second axial region, or in that the two axial regions of the inner wall of the inner cap part overlap. 
   Advantageously, the valve body is guided on the inner cap part wherein the valve body has a guide sleeve disposed facing away from the profiled sealing ring, with the guide sleeve cooperating with a guide ring protruding axially from the inner cap part, and/or, a compression spring that acts on the valve body is retained inside the guide ring. 
   To simplify assembly, the inner cap part is divided in two in that the inner cap part is axially divided in two. 
   With these characteristics of whereby the valve body has a central opening, through which a negative-pressure valve body protrudes, whose sealing seat surrounds the central opening and rests on a further axial sealing face of the valve body, and the further axial sealing face is part of the axially effective sealing face arrangement or of the profiled sealing ring, and the negative-pressure valve body prestressed against the further axial sealing face of the valve body with the aid of a spring braced on the top side of the valve body, an advantageous disposition of a negative-pressure valve body in the sealing cap is achieved. 
   To provide a remedy for unscrewing the sealing cap, the outer cap part on which the inner cap part is retained in a suspended fashion, is formed by grip and closure elements that are rotatable relative to one another, and for their releasable connection in a manner fixed against relative rotation, an axially movable coupling insert is provided, whose axial motion is derived from the pressure-dependent axial motion of a sole valve body are provided in a sealing cap of this kind, so that its torsion prevention upon overpressure can be established in a way that is simpler both structurally and in terms of production and is therefore more economical. This is because, as a result of the direct derivation of motion from the sole valve body, no additional components are necessary; instead, idle travel is achieved between the closure element that carries the thread or the like and the grip element or actuating handle upon overpressure. This idle travel connection at overpressure has the substantial advantage, compared with blocking the sealing cap upon overpressure, that the activation of the torsion prevention becomes visually noticeable, thus precluding possible exertions of force in the event of blockage. 
   Further space is saved for the valve arrangement in that the axially movable coupling insert is disposed inside the grip element of the outer cap part. 
   A reinforcement of the axial motion of the coupling insert is obtained in that an axial spring coupling for disengagement and/or engagement of the coupling insert is provided between the axially movable coupling insert and the valve body. For guiding the valve body and the coupling insert in the back and forth motion, the axially movable guide element is provided between the axially movable coupling insert and the valve body. It may be expedient to embody the guide element so that it is axially movable inside the hollow coupling insert and is retained in a maximal extension position by end stop elements. The sleeve element can thus actively return the coupling insert from its disengaged position to its engaged position in conjunction with the spring coupling. The guide element and the coupling insert are retained rotatably relative to one another. 
   Preferred features and dispositions of the compression springs of the spring coupling of the valve body, guide element and inner cap part are also obtained by the provision of having the axial spring coupling surround the guide element, by the axial spring coupling having a first helical compression spring, which is provided between the guide element and the coupling insert, by the axial spring coupling having a second helical compression spring, which is disposed between the guide element and the inner cap part, and by the helical compression spring acting on the sole valve body surrounding the compression spring or compression springs of the axial spring coupling. 
   In a further feature of the engagement and disengagement connection of the coupling insert, the axially movable coupling insert is constantly connected in a manner fixed against relative rotation to the grip element of the outer cap part and is axially movable relative to them and is connectable releasably to the closure element of the outer cap part by axial engagement and disengagement in the circumferential direction, and the releasable connectability in the circumferential direction is formed by an axially oriented circumferential toothing of the closure element and the coupling insert. 
   Further details of the invention can be derived from the ensuing description, in which the invention is described and explained in terms of the exemplary embodiments shown in detail in the drawing. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1 , is a longitudinal sectional view, an overpressure/negative-pressure valve arrangement of a sealing cap for a motor-vehicle radiator, in the closed outset position, in a first exemplary embodiment of the present invention; 
       FIG. 2 , is a somewhat enlarged half section, the sealing cap of  FIG. 1  in a position after a first limit value of the internal container pressure is exceeded; 
       FIG. 3 , is a view corresponding to  FIG. 2 , but in a position after a second limit value of the internal container pressure is reached, or a fluid head pressure is applied; 
       FIG. 4 , is a view corresponding to  FIG. 2 , but in a position after a third or safety limit value of the internal container pressure is exceeded; 
       FIG. 5 , is a longitudinal sectional view of a sealing cap for a motor-vehicle radiator with an overpressure/negative-pressure valve arrangement and torsion prevention in the closed or nonactivated outset position, in a second exemplary embodiment of the present invention; 
       FIG. 6 , is a view corresponding to  FIG. 5 , but in a position during the buildup of an overpressure in the container interior; 
       FIG. 7 , is a view corresponding to  FIG. 5 , in a position after a first limit value is exceeded but before a second limit value of the internal container pressure is reached; 
       FIG. 8 , is a position corresponding to  FIG. 5 , but in a position after a third or safety limit value of the internal container pressure is exceeded; and 
       FIG. 9 , is a view corresponding to  FIG. 5 , but in a position after the normal pressure is reached in the container interior and before the torsion prevention is reversed or undone. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The sealing cap  11  shown in  FIGS. 1–4 , for instance for a motor-vehicle radiator, in a manner not shown has an outer cap part, which is provided with an actuating handle and on which an inner cap part  14  with a negative-pressure/overpressure valve arrangement  15  is retained. In the position for use, the sealing cap  11  is fixed on a radiator neck, not shown, for instance being screwed onto it. The inner cap part  14  protrudes in the radiator neck in the direction of the radiator interior. An O-ring  16  seals the inner cap part  14  off from the radiator neck wall. The overpressure part of the valve arrangement  15  is embodied in two stages and in a first overpressure stage serves to prevent the radiator from boiling dry, while in a second overpressure stage, security against damage to the radiator system from excessive overpressure is assured. 
   The overpressure part of the valve arrangement  15  has a single valve body  1 , which is axially movable between two terminal positions inside the inner cap part  14 . The valve body  17  has a profiled ring seal  18 , which has both an axially effective sealing face arrangement  20  and a radially effective sealing face arrangement  21 . The valve body  17  is axially prestressed inward in the direction of the container interior by means of a compression spring  22  braced on the inner cap part  14 . 
   The inner cap part  14  is embodied in two parts and is thus composed of an inner, upper element  25  and an outer main element  26 , which is retained in the outer cap part in a manner not shown and in which the inner, upper element  25  is fixed in sealed fashion. The inner, upper element  25  has a coaxial guide ring attachment  27 , which protrudes inward from the top  28  of the element  25 . This guide ring attachment  27  receives one end of the compression spring  22 , which is braced on the inside of the top  28 . On the outer circumference, the guide ring attachment  27  serves to provide axial guidance of the valve body  17 . At the level of the guide ring attachment  27 , the inner cap part  14  is provided with radial outflow openings  29  on the outer circumference. Between the inner, upper element  25  and the main element  26 , an O-ring  24  is provided for the sake of tight connection. 
   The main element  26  of the inner cap part  14 , on its bottom  31 , has a flowthrough opening  32 , in this case coaxial, which forms a communication between the container interior and the interior of the inner cap part  14 . The flowthrough opening  32  is surrounded coaxially by an annular attachment  33  that protrudes toward the inside of the inner cap part  14 , and its free annular face end forms a sealing seat  34  for the axially effective sealing face arrangement  20  of the profile ring seal  18  of the valve body  17 . Between the outer circumference of the annular attachment  33  and the inner circumference of the main element  26 , an annular chamber  36  remains in this region. Above this annular chamber  36 , the main element  26  of the inner cap part  14  has an annular groove  37 , which is open axially outward and in which an annular insert  38  is received that contains or forms a U-shaped throttling conduit  39 . In the exemplary embodiment shown, the U-shaped throttling conduit  39  is provided at a point on the circumference of the main element  26  of the inner cap part  14 . The throttling conduit  39  has two radial conduit parts  41  and  42 , axially spaced apart from one another, which are joined together by an axial conduit part  43  that is located between the applicable inner circumference region of the main element  26  and the applicable outer circumference region of the annular insert  38 . The conduit parts  41  and  42  are formed here by radial grooves cut into the annular insert  38 , while the conduit part  43  is formed by an axial groove cut into the main element  26 . 
   The one-piece valve body  17  has a main part  46 , which is radially stepped in the axial direction and which carries the profile ring seal  18 , and a guide part  47 , remote from the profile ring seal  18 , which is hollow-cylindrical and is guided on the guide ring attachment  47 , which it grips, of the inner cap part  14 . The compression spring  22  is braced on an inner shoulder, remote from the profile ring seal  18 , of the valve body  17 . 
   The profile ring seal  18  is secured to a stepped outer circumferential region of the valve body  17 . The axially effective sealing face arrangement  20  of the profile ring seal  18  is arched, viewed in cross section, and has a radially outer sealing face  51 , a radially middle sealing face  52 , and a radially inner sealing face  53 . The radially inner sealing face  53  cooperates with a negative-pressure valve body  71  to be described hereinafter; the radially middle sealing face  52 , in the position of repose of the valve arrangement  15 , rests on the sealing seat  34  of the inner cap part  14 ; and the radially outer sealing face  51  rests on the bottom of the annular chamber  36 . By comparison, the radially effective sealing face arrangement  21  has two sealing faces  56  and  57  which are disposed at a defined axial spacing and between which a clearance  58  is provided. Both the upper sealing face  56  and the lower sealing face  57 , which merges with the radially outer sealing face  51 , rest sealingly on the inner wall  61  and/or  62 , embodied as a sealing seat, of the main element  26  of the inner cap part  14  and of the annular insert  38 , respectively. 
   In the center of the valve body  17 , an opening  66  is provided, which is closed on the side toward the radiator interior by the negative-pressure valve body  71  of the valve arrangement  15 . The negative-pressure valve body  71  protrudes with its main part  72  through the central opening  66  and is acted upon in the end region thereof by a compression spring  67 , which is braced on one end on a shoulder of the main part  72  and on the other on the outer face of the inner shoulder of the valve body  17 , on which the compression spring  22  also rests. In this way, the negative-pressure valve body  71  is pressed sealingly with its annular sealing seat  73  against the radially inner sealing face  53  of the axially effective sealing face arrangement  20  of the profile ring seal  18  of the valve body  17 . 
   In the position of repose, or outset operating position, shown in  FIG. 1 , in which a first limit value of the internal container pressure has not yet been exceeded, any flow connection between the container interior and container exterior is closed as a result of the sealing contact of all the sealing faces  51 – 53  of the axially effective sealing face arrangement  20  of the profile seal  18  of the valve body  17  against the respective sealing seats  36 ,  34 ,  73  of the inner cap part  14  and of the negative-pressure valve body  71 , respectively. In other words, through the flowthrough opening  32 , the pressure prevailing in the interior of the container is present in the form of the air cushion, located above the liquid radiator medium, at both the profile ring seal  18  of the valve body  17  and the underside of the negative-pressure valve body  71 . 
   If the internal container pressure increases above the predetermined first limit value, then the valve arrangement  15  of the sealing cap  11  reaches the operating state shown in  FIG. 2 , in which the valve body  17 , counter to the action of its compression spring  22 , lifts with its radially middle sealing face  52  from the sealing seat  34 , and the profile ring seal  18  reaches the region of the annular insert  38 , in such a way that the two radial sealing faces  56  and  57  of the radially effective sealing face arrangement  21  of the profile ring seal  18  of the valve body  17  are located above and below the radial conduit parts  41  and  42 , respectively, and thus open the throttling conduit  39  on both ends. In this operating state, an equilibrium has been established between the action of the internal container pressure and the contrary action of the compression spring  22 . Thus a first flow connection between the container interior and the container exterior is opened, leading from the flowthrough opening  32  via the U-shaped throttling conduit  39  to the outflow openings  29 . As a result, air from the air cushion located above the liquid radiator medium can flow to the outside and compensate for or reduce the overpressure. If as a result the overpressure is reduced to below the first limit value, then the valve body  17  returns to sealing contact with the axial sealing seat  34  of the inner cap part  14 . 
   Conversely, if the internal container pressure increases further even during or after the elimination of the air cushion, and if this causes liquid radiator medium to reach the underside of the profile ring seal  18  and of the negative-pressure valve body  71 , then the result, because of the very narrow throttling conduit  39  (with a cross-sectional size on the order of a few hundredths of a millimeter) is a backup of the liquid radiator medium at the entrance to the lower radial conduit part  42  of the throttling conduit  39 , and thus a head pressure at the full-surface undersides of the profile ring seal  18  and negative-pressure valve body  71 . This head pressure causes an axial motion of the valve body  17  onward, counter to the action of the compression spring  22 , so that in the operating state of  FIG. 3 , the throttling conduit  39  is closed again at the upper radial conduit part  41 . In this operating state, the throttling conduit  39  is thus closed in such a way that its upper radial conduit part  41  opens into the clearance space  58  between the two sealing faces  56  and  57  of the profile ring seal  18 . An ejection of liquid radiator medium is thus prevented. If the internal container pressure is reduced by cooling down of the motor-vehicle radiator, and the liquid radiator medium is thus returned, then the valve body  17  can also be restored under the action of its compression spring  22 , so that the throttling conduit  39  opens again, and a further pressure buildup can take place. 
   Conversely, if the internal container pressure continues to increase, then when an upper (safety) pressure limit value is exceeded, the valve body  17  is lifted farther, counter to the compression spring  22  loading it, so that windows  69  located at certain circumferential regions in the wall of the inner cap part  14 , which communicate with the container interior ( FIG. 4 ) in a manner not shown, are opened. In this state, as before, the upper conduit part  41  opens into the clearance space  58 , which has no communication with the outflow openings  29 . This upper terminal position of the valve body  17  is defined by the contact of an inner step  48  of the valve body  17  with the free annular face end of the guide ring attachment  27  of the inner cap part  14 . As a result, the aforementioned overpressure can be reduced via a second flow connection, after which a corresponding restoration of the valve body  17  over the various operating states can occur. 
   The outset position shown in  FIG. 1  is assumed by the valve arrangement  15  whenever the internal pressure in the radiator is moving between a negative-pressure limit value and the first overpressure limit value. Such pressure conditions exist for instance in a vehicle that has been parked for a relatively long time, or during vehicle travel when there is adequate cooling of the coolant in the radiator interior by the relative wind and/or by a fan. If after a relatively long trip the vehicle is stopped after a relatively long trip, there can be a resultant pressure increase in the radiator interior, allowing the contents of the radiator (air or water or water vapor) to flow to the valve arrangement  15 . If the coolant volume expands from this after-heating effect to such an extent that the container volume is exceeded, this would necessarily cause the expulsion of coolant. This unwanted effect is prevented, in the manner described above, because the operating state of the valve arrangement  15  as shown in  FIG. 3  is established. If in this operating state a further uncontrolled pressure rise in the cooling system occurs, then leaks and other adverse effects resulting from an overload on the radiator container and/or the hose connection points must be averted. These effects are averted by the second valve stage, in the state shown in  FIG. 4 , which limits the container pressure to a predetermined safety pressure value. 
   If negative pressure prevails in the radiator interior, and this pressure falls below a predetermined negative-pressure limit value, then beginning at the operating state shown in  FIG. 1 , the negative-pressure valve body  71  with its sealing seat  73  is lifted from the radially inner sealing face  53  of the profile ring seal  18  of the valve body  17  toward the radiator interior. The lowering of the negative-pressure valve body  71  takes place counter to the prestressing force of the compression spring  67 , so that in a manner not shown, a third flow connection between the radiator interior and the radiator exterior opens. 
   The sealing cap  111 , for instance for a motor-vehicle radiator, shown in  FIGS. 5–9  has an outer cap part  110 , which is provided with a grip element or actuating handle  112 , and on whose closure element  113 , embodied here as a screw-on element, an inner cap part  114  is kept suspended and retained relatively rotatably with a negative-pressure/overpressure valve arrangement  115 . In the position for use, the sealing cap  111  is fixed, for instance being screwed on, to a radiator neck, not shown. The inner cap part  114  protrudes within the radiator neck in the direction of the radiator interior. An O-ring  116  seals off the inner cap part  114  from the radiator neck wall. In the two-part outer cap part  110 , the caplike actuating handle  112  is axially fixed on the screw-on element  113  but is rotatable in the circumferential direction. This rotatability is blocked, at normal pressure in the radiator interior, by an axially movable coupling insert  180  for screwing and unscrewing the sealing cap  111 . 
   The overpressure part of the valve arrangement  15  is embodied in two stages and in a first overpressure stage serves to prevent the radiator from boiling dry, while in a second overpressure stage, security against damage to the radiator system from excessive overpressure is assured. 
   The overpressure part of the valve arrangement  115  has a single valve body  117 , which is axially movable between two terminal positions inside the inner cap part  114 . The valve body  117  has a profiled ring seal  118 , which has both an axially effective sealing face arrangement  120  and a radially effective sealing face arrangement  121 . The valve body  117  is axially prestressed inward in the direction of the container interior by means of a compression spring  122  braced on the inner cap part  114 . 
   The inner cap part  114  is embodied in two parts and thus is composed of an inner element  125  and an outer, main element  126 , which is kept suspended in the screw-on element  113  of the outer cap part  110  and in which the inner element  125  is fixed in sealed fashion. The inner element  125  is approximately hood-shaped, with an axial opening in the hood bottom  128 , on whose inside one end of the compression spring  122  is braced. Approximately at the level of the lower end of the outer cap part  110 , the inner cap part  114  is provided on its outer circumference with radial outflow openings  129 . Between the inner element  125  and the main element  126 , an O-ring  124  is provided for the sake of tight connection. 
   The main element  126  of the inner cap part  114 , on its bottom  131 , has a flowthrough opening  132 , in this case coaxial, which forms a communication between the container interior and the interior of the inner cap part  114 . The flowthrough opening  132  is surrounded coaxially by an annular attachment  133  that protrudes toward the inside of the inner cap part  114 , and its free annular face end forms a sealing seat  134  for the axially effective sealing face arrangement  120  of the profile ring seal  118  of the valve body  117 . Between the outer circumference of the annular attachment  133  and the inner circumference of the main element  126 , an annular chamber  136  remains in this region. Above this annular chamber  136 , between the lower annular face end of the inner element  125  and a setback in the main element  126  of the inner cap part  114 , an annular insert  138  is received that contains or forms a U-shaped throttling conduit  139 . In the exemplary embodiment shown, the U-shaped throttling conduit  139  is provided at a point on the circumference of the inner cap part  114 . The throttling conduit  139  has two axially spaced-apart radial conduit parts  141  (adjacent to the inner element  125 ) and  142  (adjacent to the setback in the main element  126 ), which are joined together by an axial conduit part  143  that is located between the applicable inner circumference region of the main element  126  and the applicable outer circumference region of the annular insert  138 . The conduit parts  141 ,  142  and  143  are formed here by radial and axial grooves cut into the annular insert  138 . 
   The one-piece valve body  117  has a main part  146 , which is radially stepped in the axial direction and which carries the profile ring seal  118 , and on which, remote from the profile ring seal  118 , a guide element  147  is seated, which is hollow-cylindrical and engages the hollow coupling insert  180 . The compression spring  122  is braced on a radial outer shoulder of the main part  146  of the valve body  117 . 
   The profile ring seal  118  is secured to the inside face of a stepped outer circumferential region of the valve body  117 . The axially effective sealing face arrangement  120  of the profile ring seal  118  is arched, viewed in cross section, and has a radially outer sealing face  151 , a radially middle sealing face  152 , and a radially inner sealing face  153 . The radially inner sealing face  153  cooperates with a negative-pressure valve body  171  to be described hereinafter; the radially middle sealing face  152 , in the position of repose of the valve arrangement  115 , rests on the sealing seat  134  of the inner cap part  114 ; and the radially outer sealing face  151  rests on the bottom of the annular chamber  136 . By comparison, the radially effective sealing face arrangement  121  has two sealing faces  156  and  157  which are disposed at a defined axial spacing and between which a clearance  158  is provided. Both the upper sealing face  156  and the lower sealing face  157 , which merges with the radially outer sealing face  151 , rest sealingly on the inner wall  161  and/or  162 , embodied as a sealing seat, of the main element  126  of the inner cap part  114  and of the annular insert  138 , respectively. 
   The guide element  147 , seated with an inner end on the outer face of the inner shoulder of the valve body  117 , protrudes with its other end into the central through opening of the coupling insert  180 . The coupling insert  180  and guide element  147  are rotatable relative to one another and displaceable axially to one another. The axial displaceability is limited, as  FIG. 5  shows, by shoulders  181 ,  182  resting on one another, in such a way that the guide element  147  and coupling insert  180  always engage one another. The guide element  147  is embodied in sleevelike fashion, and its outer wall is stepped on the inner end, toward the valve body  147 , to form contact shoulders for an axial spring coupling arrangement. The spring coupling arrangement has a first, inner helical compression spring  183 , which is prestressed between the coupling insert  180  and the guide element  147 , and a second, by comparison outer, helical compression spring  184 , which is braced on one end on the guide element  147  and on the other in the inner element  125  of the inner cap part  114 . These two helical compression springs  183  and  184  are surrounded by the helical compression spring  122  that acts on the valve body  117 . 
   The axially displaceable coupling insert  180 , which with its lower end that fits over the guide element  147  penetrates a central through bore in the inner element  125  of the inner cap part  114 , rests with its outer end, of larger outer diameter, in the outset state shown in  FIG. 5 , inside a recess  186  of a radial flange  187  of the screw-on element  113  and inside a central annular flange  188  protruding axially inward on the actuating handle  112 . With the axial flange  188 , the coupling insert  180  is connected constantly nonrotatably to the actuating handle  112 , for instance by means of suitable sets of intermeshing teeth. In the outset position shown in  FIG. 5 , the coupling insert  180  is also nonrotatably connected to the radial flange  187  of the screw-on element  113 , specifically once again via circumferential, axially extending toothing arrangements, not shown. In this way, the actuating handle  112  and the screw-on element  113  are nonrotatably joined together in the circumferential direction, so that the sealing cap  111  can be screwed onto the fill neck, not shown, of a container and unscrewed from it by means of the actuating handle  112 . 
   In the center of the valve body  117 , an opening  166  is provided, which on the side toward the radiator interior is closed by the negative-pressure valve body  171  of the valve arrangement  115 . The negative-pressure valve body  171  protrudes with its main part  172  through the central opening  166  and is acted upon on its end region by a compression spring  167 , which is braced on one end on a shoulder of the main part  172  and on the other on the outer face of the inner shoulder of the valve body  117 . In this way, the negative-pressure valve body  171  is pressed sealingly with its annular sealing seat  173  against the radially inner sealing face  153  of the axially effective sealing face arrangement  120  of the profile ring seal  118  of the valve body  117 . 
   In the position of repose or outset operating position shown in  FIG. 5 , in which as yet no overpressure prevails in the container interior, any flow connection between the container interior and container exterior is closed as a result of the sealing contact of all the sealing faces  151 – 153  of the axially effective sealing face arrangement  120  of the profile seal  118  of the valve body  117  against the respective sealing seats  136 ,  134 ,  173  of the inner cap part  114  and of the negative-pressure valve body  171 , respectively. In other words, through the flowthrough opening  132 , the pressure prevailing in the interior of the container is present in the form of the air cushion, located above the liquid radiator medium, at both the profile ring seal  118  of the valve body  117  and the underside of the negative-pressure valve body  171 . 
   If the internal container pressure increases to a certain amount, which is above the normal pressure but below a first limit value of the internal container pressure, then the unscrewing prevention of the sealing cap  111  is activated. As shown in  FIG. 6 , the valve body  117  is moved upward, so that the profile ring seal  118  lifts with its middle sealing face  152  from the sealing seat  134 . This enlarges the effective area acted upon by the overpressure, an area that until now was formed only by the underside of the negative-pressure valve body  171 , around the inner axial face of the profile ring seal  118 . This larger effective area, for the same pressure, exerts a greater force on the valve body  117  and results in a lengthened stroke thereof. As a result of the reciprocating motion of the valve body  117 , which however does not yet open the throttling conduit  139 , counter to the action of the first helical compression spring  183  and the second helical compression spring  184 , the guide element  147  is initially axially displaced relative to the coupling insert  180 . Since as a result of this reciprocating motion the first helical compression spring  183 , which is braced on the coupling insert  180 , is prestressed, the coupling insert  180  is axially displaced. As a result of this axial motion outward of the coupling insert  180  in the direction of the arrow A and up to an inner stop at the underside of the actuating handle  112 , the coupling insert  180 , on its larger-diameter end, comes free of the toothing on the screw-on element  113 . This disengagement motion of the coupling insert  180  causes the actuating handle  112  to revolve idly relative to the screw-on element  113 , so that beyond a certain defined overpressure (in this case, 0.3 bar, for instance), unscrewing of the sealing cap  111  is no longer possible. 
   If the internal container pressure increases further, that is, beyond the predetermined first limit value (for instance of 1.4 bar), then the valve arrangement  115  of the sealing cap  111  reaches the operating state shown in  FIG. 7 , in which the valve body  117  lifts away farther, counter to the action of its compression spring  122 , and the profile ring seal  118  reaches the region of the annular insert  138  in such a way that the two radial sealing faces  156  and  157  of the radially effective sealing face arrangement  121  of the profile ring seal  118  of the valve body  117  are located above and below the radial conduit parts  141  and  142 , respectively, and thus open the throttling conduit  139  on both ends. In this operating state, in which the unscrewing prevention continues to remain activated, an equilibrium has been established between the action of the internal container pressure and the contrary action of the compression spring  122 . Thus a first flow connection between the container interior and the container exterior is opened, leading from the flowthrough opening  132  via the U-shaped throttling conduit  139  to the outflow openings  129 . As a result, air from the air cushion located above the liquid radiator medium can flow to the outside and compensate for or reduce the overpressure. If as a result the overpressure is reduced to below the first limit value, then the valve body  117  resumes its sealing contact with the axial sealing seat  134  of the inner cap part  114 . 
   Conversely, if the internal container pressure increases further even during or after the elimination of the air cushion, and if this causes liquid radiator medium to reach the underside of the profile ring seal  118  and of the negative-pressure valve body  171 , then the result, because of the very narrow throttling conduit  139  (with a cross-sectional size on the order of a few hundredths of a millimeter) is a backup of the liquid radiator medium at the entrance to the lower radial conduit part  142  of the throttling conduit  139 , and thus a head pressure at the full-surface undersides of the profile ring seal  118  and negative-pressure valve body  171 . This head pressure causes an axial motion of the valve body  117  onward, counter to the action of the compression spring  122 , so that in this operating state for instance with a pressure of 1.5 bar, at the upper radial conduit part  141 , the throttling conduit  139  is closed again in a manner not shown by the upper radial sealing face  156  of the profile ring seal  118 . The unscrewing prevention continues to be activated. An ejection of liquid radiator medium is thus prevented. If the internal container pressure is reduced by cooling down of the motor-vehicle radiator, and the liquid radiator medium is thus returned, then the valve body  117  can also be restored under the action of its compression spring  122 , so that the throttling conduit  139  opens again, and a further pressure buildup can take place. 
   Conversely, if the internal container pressure continues to increase, then when an upper (safety) pressure limit value (for instance of 2 bar) is exceeded, the valve body  117  is lifted farther, counter to the compression spring  122  loading it, so that axial outflow conduits  169 , located at certain circumferential regions in the wall of both the annular insert  138  and the inner element  125  of the inner cap part  114 , are opened, which are in communication with the outflow opening  129  and therefore with the container exterior ( FIG. 8 ). In this operating state, as before, the upper conduit part  141  is still closed. This upper terminal position of the valve body  117  is defined by the compressed compression springs  122 ,  183 , and  184 . The unscrewing prevention continues to remain activated. As a result, the aforementioned overpressure can be reduced via a second flow connection, after which a corresponding restoration of the valve body  117  over the various operating states can occur by means of the compression spring  122 , as is shown in  FIG. 9 . 
     FIG. 9  also shows one possible brief state of the unscrewing prevention, whenever the valve body  117  has returned to its outset position and rotation of the actuating handle  112  has occurred while the unscrewing prevention was activated. In that case, it might have happened that the coupling insert  180  with its toothing failed to come precisely above the tooth gaps in the toothing of the unscrewing element  113 . In order in this case to return the unscrewing prevention from its activated state to its deactivated state in accordance with  FIG. 5 , a brief rotary actuation of the actuating handle  112  suffices; this causes the outer, second helical compression spring  184 , which is under considerable prestressing, to move the guide element  147  downward, counter to arrow A. This relaxes the inner, first compression spring  183 , and the guide element  147 , with its outer annular shoulder  181 , as a result of contact with the inner annular shoulder  182  of the coupling insert  180 , carries this coupling insert along with it in the direction of arrow A, so that the coupling connection between the actuating handle  112  and the unscrewing element  113  is reengaged or comes into effect again. The overall operating position of  FIG. 5  is thus achieved, and the sealing cap  111  can be unscrewed from the fill neck of the radiator without danger. 
   The outset position shown in  FIG. 5  is assumed by the valve arrangement  115  whenever the internal pressure in the radiator is moving between a negative-pressure limit value and an only very slight overpressure value, in this case of less than 0.3 bar. Such pressure conditions exist for instance in a vehicle that has been parked for a relatively long time, or during vehicle travel when there is adequate cooling of the coolant in the radiator interior by the relative wind and/or by a fan. If after a relatively long trip the vehicle is stopped after a relatively long trip, there can be a resultant pressure increase in the radiator interior, allowing the contents of the radiator (air or water or water vapor) to flow to the valve arrangement  115 . If the coolant volume expands from this after-heating effect to such an extent that the container volume is exceeded, this would necessarily cause the expulsion of coolant. This unwanted effect is prevented. If in this operating state a further uncontrolled pressure rise in the cooling system occurs, then leaks and other adverse effects resulting from an overload on the radiator container and/or the hose connection points must be averted. These effects are averted by the second valve stage, in the state shown in  FIG. 8 , which limits the container pressure to a predetermined safety pressure value. 
   If negative pressure prevails in the radiator interior, and this pressure falls below a predetermined negative-pressure limit value, then beginning at the operating state shown in  FIG. 5 , the negative-pressure valve body  171  with its sealing seat  173  is lifted from the radially inner sealing face  153  of the profile ring seal  118  of the valve body  117  toward the radiator interior. The lowering of the negative-pressure valve body  171  takes place counter to the prestressing force of the compression spring  167 , so that in a manner not shown, a third flow connection between the radiator interior and the radiator exterior opens.