Abstract:
A closure cap for a fixed neck of a container, especially of a motor vehicle radiator. The closure cap comprises a cap inner part provided with a flow connection between the inside of the container and the outside of the container. The cap inner part includes a valve assembly for releasing and blocking the flow connection. The valve assembly includes a valve body is able to move in a to-and-fro manner. It is pressed with a bias in a direction toward the interior of the container against a sealing seat. The valve body is biased so that it can lift from the sealing seat when a limiting value of the inner pressure of the container is surpassed. The bias can be adjusted by a drive controlled by the operation of the vehicle.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a closure cap for a stationary connector of a container, in particular a motor vehicle radiator having an interior cap element, which has a flow connection between the container interior and the container exterior, and a valve arrangement for opening and blocking the flow connection, wherein a valve body, which can be moved back and forth is pushed with a bias in the direction toward the container interior against a seal seat on the interior cap element so that it can lift off the seal seat when a threshold value of the interior pressure in the container is exceeded. 
     BACKGROUND OF THE INVENTION 
     In connection with known closure caps, for example for motor vehicle radiators, the valve body of the valve arrangement is constantly charged in such a way that the flow connection between the radiator interior and the radiator exterior is opened after a defined threshold value of the interior radiator pressure has been exceeded. This then results in the discharge of air interspersed with coolant water. Such simple closure caps provide a pressure equalization during the operation of the motor vehicle at the time when the pressure in the radiator increases, caused by the heating of the cooling water, and a critical pressure value has been reached or exceeded. This is a safety aspect. However, in motor vehicles the overpressure also rises because of residual heat when the vehicle is stopped, i.e. the engine has been shut down, so that in connection with the simple closure cap mentioned a complete opening also takes place and the danger arises that a large amount of cooling water escapes, or evaporates, or the radiator even boils empty, so that cooling water must be frequently replenished. Multi-stage closure caps were therefore developed (DE 41 07 525 C1), which release the overpressure created by the residual heat in other ways than an essentially higher overpressure occurring because of a malfunction. However, such a closure cap is relatively elaborate because of several valve body elements, which can be moved in respect to each other, and because of several sealing and counter-sealing surfaces. Moreover, cooling water is also sprayed out in the course of this pressure relief in case of an overpressure caused by residual heat after the vehicle engine has been shut off. An absolute loss of water can in this case only be prevented if a compensating reservoir for catching the fluid is installed, or an additional recirculating pump is used, which prevents a pressure increase after shut-down by recirculating the coolant. But this is also elaborate. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to provide a closure cap of the type mentioned at the outset, by means of which, on the one hand, an opening in case of overpressure caused by residual heat is prevented in a simple and cost-efficient manner and, on the other hand, it remains assured that the container is protected during further increase in pressure. 
     To attain this object in connection with a closure cap of the type mentioned at the outset the bias with which the valve body is pressed against the seal seat can be set by means of a drive mechanism controlled by the vehicle operation. 
     By means of the measures of the invention it has been achieved that it is possible to control the bias of the valve body, for example as a function of the operation of a motor vehicle, in such a way that the closure cap does not open in case of a defined overpressure caused by residual heat. By means of this the discharge of air mixed with cooling water is prevented during this “operational phase”. There is no need here for additional components, such as a compensating container or a recirculating pump. The overpressure can be caused by cooling of the vehicle radiator during stops. In spite of this, the closure cap will open during a continued pressure increase beyond a defined safety limit in order not to endanger the cooling system by bursting, occurring leaks, also in connecting hoses. For example, the bias can be set in two stages, i.e. to an opening pressure corresponding to normal operations, and a higher opening pressure, which takes into consideration the pressure increase through residual heat. The setting of the bias for the valve body can take place in that the drive mechanism for biasing the valve body is vacuum-controlled, or in that the drive mechanism for biasing the valve body is electro-thermally controlled in different ways. If the bias is controlled by vacuum, the control value can be picked up directly from the engine compartment of spark ignition engines, or Diesel engines. If, however, an electrical signal is provided, it can be directly derived, for example from the operating state of the ignition. 
     Exemplary embodiments in regard to the mechanical biasing of the valve body ensue in that on the side facing away from the drive mechanism, the valve body is biased by means of a spring, or in that on its end facing away from the valve body the spring is supported on a pressure member, which is axially movable by means of the controlled drive mechanism. 
     The drive mechanism itself can be embodied in various ways, such as the controlled drive mechanism has an element, which transfers the drive motion to the pressure member, the drive mechanism is constituted by an arrangement, which has a spring-loaded diaphragm, whose axial movement biases the valve body, or the drive mechanism has an element which can be expanded by heat and is arranged axially flush with the pressure member show by way of examples. While in the first case a mechanical piston reacting to a vacuum is provided, and in the second case a diaphragm arrangement which can be moved by a vacuum, in the third case an electric drive mechanism in the form of an electrically heatable expansion element is provided. 
     Embodiments regarding the individual types of drive mechanisms ensue when the controlled drive mechanism is constituted by a piston-cylinder unit, whose piston is maintained between two springs at the ends and is provided with a ramp facing the pressure member, with a roller element arranged between the ramp of the piston and the pressure member, or when the pressure member is clamped, axially movable, by means of the diaphragm between the exterior element and exterior thread element and is biased by means of a compression spring supported on the handle, with a vacuum-controlled drive mechanism which can be or is connected with a hose leading to the engine, or when the drive mechanism has an element which can be expanded by heat and is arranged axially flush with the pressure chamber, the drive mechanism constituting an electrically heatable expansion material element, or an electrically heatable sorption actuator, preferably a metal hydride actuator, with the drive mechanism being provided with a PCT heating element, or when the drive element has a bellows in which the element which can be expanded by heat is arranged. 
     The handle is provided with a fixed hose connection element so that a fixed connection between the vacuum hose and the closure cap is provided. It is advantageous to design the release from, or screwing on, of the closure cap on the container connector in accordance with a ratchet-like rotary connecting device is provided between the handle and the exterior thread element, which can be set as a function of the direction of rotation, or in that the ratchet-like rotary connecting device is axially arranged, or in that the ratchet-like rotary connecting device is radially arranged or in that the ratchet-like rotary connecting device has a coupling bolt, which is maintained resiliently movable in its axial direction in a recess of the handle, or in that one side of the end of the coupling bolt which enters into the exterior thread element is provided with an inclined face and can be rotated in its recess, preferably over an angle of +/−180°, or in that the coupling bolt is connected, fixed against relative rotation, with a rotary lever, or in that the exterior thread element has a collar with bores, which can be engaged by the coupling bolt. 
     In a further embodiment, characterized in that a torsion protection device, which is controlled as a function of temperature, is arranged between the handle and the exterior thread element, or characterized in that the torsion protection device has a hoop, which is connected to move together with the drive mechanism and has end fingers which penetrate into the cutouts of the exterior thread element, or characterized in that the hoop is coupled to move together with the bellows of the drive mechanism, or characterized in that the bellows is acted upon by a spring, or characterized in that the torsion protection device is integrated into the ratchet-like rotary connecting device the closure cap is connected with a torsion protection device controlled as the function of temperature which prevents the closure cap from being unscrewed from the container connector in an operating state of too high a temperature. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1, is a schematic representation in longitudinal section (along line I—I of FIG. 2A) of a closure cap for motor vehicle radiators in accordance with a first exemplary embodiment of the present invention in a first position, 
     FIGS. 2A and 2B, are partial sectional views from above in accordance with the arrow IIA in FIG. 1, or a section along the line IIB—IIB in FIG. 1, 
     FIGS. 3A and 3B, are perspective plan views, or a partial sectional lateral view, of a closure cap for motor vehicle radiators in accordance with a second exemplary embodiment of the present invention, 
     FIGS. 4 and 5, are schematic longitudinal sectional representations of a closure cap in accordance with a second exemplary embodiment in a first, or a second active position, 
     FIGS. 6 and 7, correspond to FIGS. 4 and 5, but of a closure cap in accordance with a third exemplary embodiment of the present invention, 
     FIGS. 8A and 8B, is a section along the line VIIIA—VIIIA in FIG. 6, or a section along the line VIIIB—VIIIB in FIG. 7, and 
     FIG. 9, is a schematic representation in longitudinal section of a closure cap for motor vehicle radiators in accordance with a fourth exemplary embodiment of the present invention in a first position. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The closure cap  10 ,  110 ,  210 , or  310 , represented in the drawings in accordance with four exemplary embodiments has a pressure-relief valve arrangement  11  and is actuated in such a way that the opening pressure of the pressure-relief valve arrangement  11  can be set in two stages by means of a drive mechanism  15 ,  115 ,  215 , or  315 , namely to an opening pressure, which takes the motor vehicle radiator overpressure during normal operations into consideration, and an opening pressure which corresponds to the higher motor vehicle radiator overpressure resulting because of the residual heat when the motor vehicle engine has been turned off. 
     In accordance with FIGS. 1,  2 A and  2 B, the closure cap  10  has an exterior element  12  with a handle  13  and an exterior thread element  17  for screwing the closure cap  10  on and off the opening of a connector of a motor vehicle radiator, not represented, or other container, and an interior element  14 , which can be sealingly inserted by means of an O-ring  16  into the connector of the motor vehicle radiator, or other container, and is maintained on the exterior element  12 . The handle  13  is rotatably and rigidly or lockably connected with the exterior thread element  17 , wherein a torsion protection device can be provided, which operates by applying pressure, but preferably as a function of the temperature. It is understood that the exterior element  12  can also be provided with a bayonet closure element in place of an exterior thread element  17 . 
     The cylindrically embodied interior element  14  of the closure cap  10  is equipped with a pressure-relief valve arrangement  11 . It has a bottom  18  and above the bottom an inward projecting annular rim  19 , whose upper area is provided with a seal seat  21  for the valve body  22  of the pressure-relief arrangement  11 . The valve body  22  has a centered hat-shaped part  23 , on whose circumferential flange  24  a seal disk  26  rests. The hat-shaped part  23  is supported via a spring support  27  on the bottom  18 . A compression spring  28 , or pressure-relief valve spring, acts on the seal disk  26  and is supported on the other end on a sleeve  29 , which is guided, axially movable up and down, in an axial stop  34  for the guide cylinder  31  having the sleeve  29 . The guide cylinder  31  is fastened on the end of the interior element  14  which faces away from the valve body  22 . Openings  32 , which point into the motor vehicle radiator, or container, are provided on the bottom. The interior element  14  moreover has openings  33 , which are located on the exterior circumference, are of a lesser diameter and are connected with the exterior atmosphere. With the valve body  22  lifted off the seal seat  21 , a flow connection between the radiator, or container interior, and the exterior air results. 
     A pressure member  36  is received in the sleeve  29  in a motionally connected manner, whose other end projects into a chamber  39  in the exterior element  12  and has a roller or cylinder receiver  37 . A roller, or a cylinder  38  is seated, or inserted, freely rotatable in this receiver  37  of the pressure member  36 . The cylinder  38  lies at least partially inside the cylindrical chamber  39 , which is horizontal here and can be sealingly closed at its open end with the aid of an easily removable coupling element  61 , on which a hose  62  leading to the motor, for example, is fastened. A piston  46  is guided inside the cylinder chamber  39  and is movable back and forth in the direction of the two-headed arrow A, and therefore perpendicularly in respect to the movement of the pressure member  36  in accordance with the two-headed arrow B. A shifting spring  49  (FIG. 2A) is provided between the coupling element  61  and the oppositely located end of the piston  46 . The end  63  of the piston  46  facing away from the coupling element  61  is guided in a blind bore  64  at the other end of the handle  13 . The end of the piston  46  of lesser diameter is enclosed in a compression spring  65 , whose other end is supported on the bottom of the blind bore  64 . Facing the pressure member  36 , the piston  46  has a ramp  48 , against which the cylinder  38  of the pressure member  36  rests. At a location opposite the ramp  48 , the piston  46  is provided with two cutouts  51 , into each of which a roller or cylinder  50  has been inserted, freely rotatable, which cylinders  50  are supported by rolling off the interior wall of the chamber  39 . 
     The function of the control of the pressure-relief valve arrangement  11  of the closure cap  10  is as follows: when the coupling element  61  with the hose  62  constituting a vacuum line to the engine compartment is snapped into the cylinder chamber  39  of the handle  13  of the closure cap  10 , the shifting spring  49  is mechanically biased so that it, starting at the position in FIG. 1, pushes the piston  46  inward. By means of this the pressure member  36  is moved via the ramp  48  and the cylinder  38  in the direction of the arrow B 1  (downward), so that the pressure-relief valve spring  28  is biased. In this way the valve body  22  is provided with an increased opening pressure. 
     Since a vacuum is created when the motor vehicle engine is started, the piston  46 , which is conducted, sealed against pressure, in the chamber  39 , is pulled in the direction of the arrow A 2 , because of which the piston  46  is pulled back into the position in accordance with FIG.  1 . By means of this the pressure member  36  is moved in the direction of the arrow B 2  (upward) by the action of the compression spring  28 , so that the compression spring  28  is slightly relaxed. This results in a reduced opening pressure for the valve body  22 , which customarily is set at approximately 1.4 bar. After the motor vehicle engine has been turned off, no vacuum is applied to the piston  46  anymore, so that the shifting spring  49  can then move the piston  46  again in the direction of the arrow A 1  against the action of the spring  65 . The pressure-relief valve spring  28  is tensed again in this way, so that an opening pressure, increased to approximately 2.0 bar, on the valve body  22  results. Because of this the valve body  22  can withstand a higher interior radiator, or container, pressure resulting from the residual heat of the turned-off engine. 
     If the coupling element  61  is uncoupled for opening the closure cap  10 , for example for replenishing coolant, the shifting spring  49  is completely relaxed, so that the pressure-relief valve spring  28  automatically switches in the manner described above to the normal operation opening pressure of, for example 1.4 bar. If after the closure cap  10  has been screwed on again the coupling of the coupling element  61  with the closure cap  10  is forgotten, the lower normal operation opening pressure is automatically maintained, so that the motor vehicle can continue to be used. 
     A ratchet-like operating torsion protection device, or rotary connecting device  80 , between the exterior element  12  and the interior element  14  with the exterior thread element  17 , with which the pressure-relief valve arrangement  11  is connected, has a coupling element in the form of a coupling bolt  82 . A ring of axial bores  84  is provided in an upper wall  83  of the exterior thread element  17  located opposite the axially movable coupling bolt  82  arranged in a circumferential area of the handle  13 , into respectively one bore  84  of which the inner free end  90  of the coupling bolt  82  selectively enters for a rotary connection of the handle  13  and the exterior thread element  17 . In this position the closure cap  10  can be removed from the radiator connector. The coupling bolt  82  is conducted, movable up and down on a bearing sleeve  88  maintained in the bore  86  of the handle  13 , and its collar, which is fixed against relative movement, is acted upon by a compression spring  85  in the direction toward the bore rim  83 . The coupling bolt  82 , whose end  90  entering into the bore  84  has an inclined face  89  over approximately 180° of its circumferential area, can be turned to the left or right by 180° via a head slot  87  by means of a screwdriver in accordance with FIG.  2 B. In this way the coupling bolt  82  is in engagement with the bore  84 , corresponding to the position of the inclined face, when the handle  13  is turned to the right or left, while it can freely turn in the manner of a ratchet in the respectively opposite direction, which is achieved by the resilience of the coupling bolt  82  against the effects of the compression spring  85  acting on it. 
     In the second exemplary embodiment represented in FIGS. 3A,  3 B,  4  and  5 , the pressure member  136 , facing away from the compression spring  128 , is acted upon by an actuating spring  154 , one end of which is supported on the pressure member  136 , and the other end is supported centered on the inner wall of the handle  113 . The center of the pressure member  136  is seated, axially movable, on a diaphragm  155 , wherein the circumferential rim of the diaphragm  155  is clamped between the handle  113  and the exterior thread element  117 . In comparison with the pressure member  36 , this pressure member  136  has a larger surface viewed from above and projects essentially into the chamber  139  which is connected with the vacuum line to the engine. 
     As with the first exemplary embodiment, when there is no vacuum in the chamber  139 , and therefore none is applied to the pressure member  136 , with the engine turned off, the actuating spring  154 , which has a greater force than the compression spring  128 , biases the latter, so that the valve body  122  can withstand an opening pressure of approximately 2.0 bar (FIG.  5 ). As soon as the engine is started, a vacuum occurs through the vacuum line in the chamber  139 , and therefore acts on the pressure member  136 , which has the result that the pressure member  136  is sucked into the vacuum chamber  139  against a stop represented in FIG.  4 . The actuating spring  154  is tensed by this and the compression spring  128  relaxed, so that the valve body  122  only has to withstand an opening pressure of approximately 1.4 bar. This position remains as long as the engine runs and therefore creates a vacuum. When the engine is turned off, the restoration into the position in accordance with FIG. 5 takes place. In the course of this the diaphragm  155  provides a seal between the vacuum chamber  139  and the remainder of the closure cap space, or the interior of the radiator container, and furthermore an elastic movement connection, or arrangement, of the pressure member  136  inside the closure cap  110 . 
     With the closure cap  110  represented in FIGS. 3 to  5 , the handle  113  is provided with a fixed pipe element  163  for a hose, and not with a coupling member. Thus, with this exemplary embodiment a connection remains between the handle  113  and the hose, not represented here, while screwing the closure cap  110  on, or off the coolant reservoir connector. 
     To achieve the tight screwing, or release, of the closure cap  110  in case of such a fixed connection between the closure cap and the hose, the ratchet-like rotary connecting device  180  is provided between the exterior element  112  and the exterior thread element  117 . As with the first exemplary embodiment, this ratchet connection  180  has a coupling bolt  182  which enters, urged by a spring, into one of many annularly arranged bores  184  in a circumferential rim  183  of the exterior thread element  117 . The coupling bolt  182  is located inside an axial bore  186  provided with an undercut, wherein the compression spring  185  is provided inside the undercut. On its outer end, the bolt  182  is connected with a lever  151  (FIG. 3A) in a manner fixed against relative rotation, by means of which the coupling bolt can be moved back and forth over 180°. The inner end  190  of the coupling bolt  182  is provided with an inclined surface  189 , which is arranged pointing to the left or the right, corresponding to the position of the lever  191  in accordance with FIG.  3 B. 
     In this way the closure cap  110  (the same as the closure cap  10 ) can be screwed on the container connector or screwed off it by turning it back and forth, depending on the position of the lever  191 . In other words, depending on the position of the lever  191 , and therefore the position of the inclined face  189 , a connection, fixed against relative rotation, between the handle  113  and the exterior thread element  117  exists in the one direction, while in the other direction a free-wheeling ratchet effect is achieved because the coupling bolt  182  can come out of the bore  184  against the action of the compression spring because of the inclined face  189  and the compression spring  185 . 
     FIGS. 6 to  8  show a closure cap  210 , whose function essentially corresponds to the closure cap  110  in accordance with FIGS. 3 to  5 . The essential difference lies in the embodiment of the ratchet-like rotary connecting device  280  which, in the exemplary embodiment of claims 6 to 8, acts radially on a circumferential area. For this purpose the coupling bolt  282  is arranged spring-loaded in a bore  286 , closed against the exterior, of the handle  213  in such a way that it is biased in a direction toward the interior, so that its end  290 , which is provided with an inclined face  289 , always engages a bore  284  of a collar, or ring  283  (FIG.  8 B), which is provided with several such bores  284  and projects away from the interior element  214  and is connected with it, fixed against relative rotation. The outer end of the coupling bolt  282  is provided with gripping strip  293 , by means of which the coupling bolt  282  can be turned by respectively 180° into the respective coupling position, i.e. for screwing it off or screwing it on. 
     The ratchet-like rotary connecting device  80 ,  180  or  280 , represented in connection with the exemplary embodiments in FIGS. 1 and 2,  3  to  5  and  6  to  8  is, in accordance with one or several further exemplary embodiments not represented in the drawings, combined with a torsion protection device, which is controlled as a function of pressure or temperature. It is achieved by means of such a torsion protection device that a connection, which is fixed against relative rotation, between the handle  13 ,  113  or  213  and the exterior thread element  17 ,  117  or  217  is only provided when the temperature in the coolant reservoir is so low that there is no danger of scalding or other danger when the closing cap is unscrewed. 
     For example, the ratchet-like rotary connecting device  80 ,  180  and/or  280  is controlled as a function of the temperature in such a way that one end of the coupling bolt  82 ,  182 , or  282  is acted upon by a temperature-dependent memory spring, and the other end by a restoring spring which, at a predetermined too high temperature in the coolant reservoir, cause the coupling bolt to be pushed out of the respective detent bore  84 ,  184 , or  284 , or to leave it. 
     Another variation of a torsion protection device controlled as a function of temperature consists in that the bore collar  83 ,  183 , or  283  is controlled in the manner described in connection with the coupling bolt in such a way that it can be engaged, or disengaged, from the latter. 
     FIG. 9 shows a further embodiment of a closure cap  310 . With this exemplary embodiment the drive mechanism  315  is arranged aligned, i.e. in an axially concentric orientation, with the compression spring  328  and is axially guided in the front face of the handle  313  of the closure cap  310 . The drive mechanism  315  extending in the axial direction is electrically actuated. Electrical contacts  357  have been conducted to the outside for this purpose. 
     In accordance with a variation, the electrically actuated drive mechanism  315  is provided in the form of an expanding material, not represented in detail, with a PTC heating element as the heat source. 
     In accordance with another variation, also not represented in detail, the drive  315  is constituted by a sorption actuator, preferably a metal hydride actuator. With this drive mechanism a PTC heating element, for example, is also employed, by means of which the metal hydride in the actuator is electrically heated to a defined temperature. The pressure in the actuator arises in accordance with the temperature, so that the drive mechanism  315  expands and acts on the pressure member  336  for biasing the compression spring  328 . If the electrical heating is stopped, the metal hydride in the actuator is cooled by exchanging heat with its surroundings, so that the pressure in the actuator drops, which results in a restoring movement and therefore relaxation of the compression spring  328 . The effects on the pressure-relief arrangement  11  occur in the described manner. 
     A corresponding effect also results with the above described expansion material element as the electrical drive mechanism, wherein a wax which expands under heat is used. With both variations the actual drive element is enclosed in a bellows  371 . 
     In the exemplary embodiment represented in FIG. 9, a torsion protection device  375 , controlled as a function of temperature, is used in connection with the electrically actuated drive mechanism  315 . The torsion protection device  375  is constituted by a hoop  376 , which rests centered on the drive element  315 , or its bellows  371  and, in the initial stage lies at a short distance from the inner wall of the handle  313 . At both ends the hoop  376  extending radially inside the chamber  339  has two fingers  377 , which are bent axially downward and enter into axial bores  378  of the exterior thread element  117 . This initial state is represented in FIG.  9 . Between its center, which extends over the bellows  371 , and the fingers  377  at the end, the hoop  376  is acted upon by a compression spring  379 . In the state represented, a rotary connection between the handle  313  and the exterior thread element  317  is provided, so that the closure cap  310  can be unscrewed, or screwed on. 
     The drive mechanism  315  will slightly extend axially when the engine is running, which causes the drive mechanism  315  to move upward in the direction of the arrow B 2  because of the still too strong force of the compression spring  328 , and to lift the blocking hoop  376  sufficiently far so that it comes to rest against the inner wall of the handle  313 . In this state the blocking hoop  376  is lifted out of the bores  378 , so that the connection, fixed against relative rotation, between the handle  313  and the exterior thread element  317  is released. If the engine is turned off, the temperature in the drive element  315  continues to increase because of the selected electrical coupling, which causes it to continue to expand in the axial direction. Because of its coming to rest against the inner wall of the handle  313 , this has the result that the drive mechanism  315  expands downward in the direction in accordance with the arrow B 1  and acts on the pressure member  336  opposite to the action of the compression spring  328  and therefore biases the latter to an opening pressure of approximately 2.0 bar. In this state, too, the free-wheeling connection between the handle  313  and the exterior thread element  317  is maintained, because the blocking loop  376  continues to remain in its uppermost position. The initial position in accordance with FIG. 9 is only achieved again after complete cooling. 
     In accordance with a further exemplary embodiment of the invention, not represented, a blocking loop represented in FIG. 9 is provided in the exemplary embodiments in accordance with FIGS. 3 to  5  and  6  to  8 . There, the blocking loop is motionally connected with the pressure member  136 , or  236 , for example. 
     It is understood that such a closure cap can also be used with the compensation containers of cooling or heating systems or the same.