Abstract:
The invention relates to a valve ( 100, 101 ) comprising a housing ( 110, 111 ), an annular sealing element ( 140, 146 ), and a displaceable closure element ( 170 ), wherein the sealing element ( 140, 146 ) and the closure element ( 170 ) are disposed within the housing ( 110, 111 ), and wherein the valve ( 100, 101 ) can be closed by placing the closure element ( 170 ) against the sealing element ( 140, 146 ). The valve ( 100, 101 ) is characterized by a hollow space ( 131, 132 ) in the region of an outer side of the sealing element ( 140, 146 ), in which a part ( 143, 144 ) of the sealing element ( 140, 146 ) can be received during thermal expansion. The invention further relates to another valve ( 102 ) in which the annular sealing element is an O-ring ( 150 ).

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention relates to a valve which comprises a housing, an annular sealing element and a movable closing element. 
         [0002]    Valves are used to control the volumetric flow of gases and liquids. A possible area of use is, for example, the cooling circuit of a motor vehicle in which the engine of the motor vehicle is cooled by means of a cooling liquid, and the heated cooling liquid is used, if appropriate, for vehicle heating purposes. The distribution of the coolant to various branches of the cooling or heating circuit is controlled by means of electrically controllable valves. 
         [0003]    A conventional valve in a cooling circuit of a motor vehicle comprises a valve housing and, within the housing, an annular sealing element and a closing element in the form of a sealing cone. The sealing element is braced via a spacer sleeve against an end stop of the housing. The closing element is connected to a lifting rod which is mounted displaceably inside the housing and via which the closing element can be placed against the sealing element in order to close the valve. The lifting rod is additionally fastened to a tension spring which exerts on the lifting rod a force which pulls the closing element away from the sealing element. 
         [0004]    To actuate the valve, a yoke arranged on the housing and an armature connected to the lifting rod are provided. An electromagnetic attraction force which acts counter to the spring force and counter to a coolant pressure (generated by a pump) can be produced between the armature and yoke, with the result that an opening and closing of the valve can be controlled. When the valve is in the closed state, the armature and yoke usually have a residual distance from one another. 
         [0005]    High coolant temperatures can adversely affect the closing behavior in the valve. A particular problem is a thermal expansion of the annular sealing element, the axial component of which expansion leads to an increase in the residual distance between the armature and yoke when the valve is closed. This is associated with a reduction in the electromagnetic closing force, with the result that the valve can have a leak. 
       SUMMARY OF THE INVENTION 
       [0006]    The object of the present invention is to provide an improved valve which allows a better and more robust closing behavior, in particular at high temperatures. 
         [0007]    According to the invention, a valve is proposed which comprises a housing, an annular sealing element and a movable closing element. The sealing element and the closing element are arranged within the housing. The valve can be closed by placing the closing element against the sealing element. The valve is distinguished by a cavity in the region of an outer side of the sealing element, in which cavity a part of the sealing element can be received during a thermal expansion. 
         [0008]    The design of the valve with a cavity in the region of an outer side, that is to say a (radially) outwardly directed side of the annular sealing element, offers a clearance for a temperature-induced deformation (volume increase) of the sealing element, with the result that an axial expansion of the sealing element can be reduced. In this way, leaktightness problems associated with the axial deformation can be reduced or avoided, with the result that the valve has a more robust closing behavior. 
         [0009]    In a preferred embodiment, the cavity is provided between the outer side of the sealing element and an inner side of the housing that is situated opposite the outer side of the sealing element. In such a configuration, the sealing element preferably has, in the region of the cavity, a sealing lip which bears against the inner side of the housing, with the result that a high degree of leaktightness can be achieved for the valve. 
         [0010]    In a further preferred embodiment, the valve further comprises a hollow-cylindrical spacer sleeve arranged inside the housing, which sleeve bears against the sealing element and presses the sealing element against an end stop of the housing. In this way, the sealing element is reliably fastened inside the housing. 
         [0011]    In a further preferred embodiment, the spacer sleeve bears against the sealing element only in the region of an outer circumference and in the region of an inner circumference of the sealing element. It is thereby possible to avoid the situation in which a thermal expansion of the spacer sleeve (in addition to the thermal expansion of the sealing element) leads to an axial deformation of the sealing element, in particular in the region of the inner circumference, which adversely affects the closing behavior. 
         [0012]    Such a configuration can be achieved, for example, with a spacer sleeve which has a stepped cross-sectional shape in a region adjoining the sealing element. In this case, the annular sealing element can likewise have a stepped cross-sectional shape with a lower portion and an upper portion, wherein one cavity is provided in the region of an outer side of the lower portion and a further cavity is provided in the region of an outer side of the upper portion. 
         [0013]    According to the invention, there is furthermore proposed a valve which comprises a housing, an annular sealing element and a movable closing element. The sealing element and the closing element are arranged within the housing. The valve can be closed by placing the closing element against the sealing element. The valve is distinguished by the fact that the annular sealing element is an O-ring. 
         [0014]    The design of the sealing element as an O-ring also makes it possible to reduce a temperature-induced axial expansion of the sealing element, with the result that the valve has a more robust closing behavior. Particularly by comparison with a conventional sealing element, the O-ring can have a relatively small volume, resulting in a relatively small thermal expansion. The O-ring also offers the possibility of fastening without a spacer sleeve, thereby making it possible to avoid problems associated therewith. 
         [0015]    For fastening purposes, it is proposed in a preferred embodiment to provide the sealing element as an O-ring which is integrally formed on the housing by means of two-component injection molding. In this way, the O-ring is fixed on the valve housing in a relatively reliable and stable manner. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    The invention will be explained in more detail below with reference to the appended figures, in which: 
           [0017]      FIG. 1  shows a schematic lateral sectional representation of a valve with an annular sealing element and cavities for an expansion of the sealing element; 
           [0018]      FIG. 2  shows a schematic representation of a lower region of the valve of  FIG. 1  to illustrate a radial expansion of the sealing element; 
           [0019]      FIG. 3  shows a schematic representation of the annular sealing element of the valve of  FIG. 1  to illustrate an axial expansion; 
           [0020]      FIG. 4  shows a schematic lateral sectional representation of a further valve with an annular sealing element and cavities for an expansion of the sealing element; 
           [0021]      FIG. 5  shows a schematic lateral sectional representation of a further valve with an O-ring as sealing element; and 
           [0022]      FIG. 6  shows a schematic representation of a lower region of the valve of  FIG. 5  to illustrate an axial expansion of the O-ring. 
       
    
    
     DETAILED DESCRIPTION 
       [0023]    Possible embodiments of electrically controllable valves are described with reference to the figures which follow. The valves, which can be used, for example, in a coolant circuit of a motor vehicle, are distinguished by a robust closing behavior which is ensured even with temperature-induced deformations of valve components. 
         [0024]      FIG. 1  shows a schematic lateral sectional representation of a valve  100 . The valve  100  comprises a housing  110  which encloses a substantially hollow-cylindrical interior  105 . On the housing  110 , which comprises, for example, a plastics material, are provided a lower connection opening  120  and a lateral connection opening  122 . The interior  105  of the valve housing is accessible to a medium via the asymmetrically arranged connection openings  120 ,  122 . With regard to the above-described coolant circuit of a motor vehicle, the lower connection opening  120  is used, for example, for feeding in a cooling liquid (conveyed via a pump), and the lateral connection opening  122  is used for discharging the cooling liquid (not shown). 
         [0025]    In the interior  105 , the valve  100  further comprises an annular sealing element  140 , referred to hereinafter as a sealing ring  140 , and a closing element  170  which interacts with the sealing ring  140  and which is designed as a sealing cone  170 . The sealing cone  170  comprises, for example, a metallic material, for example brass. The sealing ring  140 , which is formed from an elastically deformable material, such as, in particular, an elastomer material, has on each side, as seen in cross section, a respectively stepped design with a lower portion  141  and a narrower upper portion  142 . On its upper side, the upper portion  142  has a rounded-off contour in the region of an inner circumference of the sealing ring  140 . In this region, as depicted in  FIG. 1 , the sealing cone  170  can bear against the sealing ring  140 , with the result that the valve  100  is closed. The lower portion  141  of the sealing ring  140  has, in the region of the inner circumference, a shape which widens out in the direction of the lower connection opening  120 . Further details on the design of the sealing ring  140  are explained more fully further below. 
         [0026]    To fix the sealing ring  140  inside the housing  110 , the valve  100  comprises a hollow-cylindrical spacer sleeve  160  which bears against the inner side of the housing  110  and which is formed, for example, from a plastics material. By means of the spacer sleeve  160 , the sealing ring  140  is braced against an end stop  115  of the housing  110  that is present in the region of the lower connection opening  120 . As indicated in  FIG. 1 , the spacer sleeve  160  has a lateral opening  162  which is tailored to the lateral connection opening  122  of the housing  100 , so as to allow a volumetric flow from the housing interior  105  across the connection opening  122 . In a portion adjoining the sealing ring  140 , the spacer sleeve  160  also has, in cross section, a shape which widens in the direction of the sealing ring  140 . 
         [0027]    On an upper side of the housing  110 , the valve  100  has a connection plate  185  which is fastened to the housing  110  using fastening means, such as, for example, screws (not shown). On a lower side of the connection plate  185  there is provided a sealing collar  180  which rests on the spacer sleeve  160  and presses the spacer sleeve  160  in the direction of the sealing ring  140 , thereby producing the above-described bracing of the sealing ring  140  against the end stop  115 . 
         [0028]    The sealing cone  170 , which interacts with the sealing ring  140 , is connected to a lifting rod  171  or is integrally formed on the lifting rod  171 . The lifting rod  171  is mounted displaceably such that the valve  100  can be closed and opened or such that a volumetric flow through the valve  100  across the connection openings  120 ,  122  can be controlled. In the position shown in  FIG. 1 , in which the sealing cone  170  bears against the sealing ring  140 , the valve  100  is closed, which means that no volumetric flow is possible between the connection openings  120 ,  122 . 
         [0029]    On the upper side, the lifting rod  171  passes out of the valve housing  110  through the sealing collar  180 . In the region of the lifting rod  171 , the sealing collar  180  can be embodied as a sealing bush or comprise such a sealing bush, in order to seal the lifting rod  171  as it is guided through. At an upper end, the lifting rod  171  is connected to a tension spring  195  which exerts on the lifting rod  171  a force which pulls the sealing cone  170  away from the sealing ring  140  and thus opens the valve  100 . 
         [0030]    To move the lifting rod  171 , and hence the sealing cone  170 , in the direction of the sealing ring  140 , and consequently to close the valve  100 , the valve  100  comprises a yoke  190  and an armature  191  which can both be designed to be substantially cylindrical. In this arrangement, the lifting rod  171  is guided in its central position through the yoke  190 , and the armature  191  is fastened circumferentially on the lifting rod  171  in an upper region thereof. The yoke  190 , which is provided on an upper side with respect to the housing  110  and is arranged on or fastened to the connection plate  185 , has a cone-like recess on an upper side. The armature  191  has, on a lower side, a conical portion which corresponds in its contour substantially to the contour of the cone-like region of the yoke  190 . 
         [0031]    The armature  191  and yoke  190  are designed in such a way that an electromagnetic attraction force can be produced between these components in order to draw the armature  191 , which is fastened to the lifting rod  171 , in the direction of the yoke  190  and consequently to displace the sealing cone  170  in the direction of the sealing ring  140 . For this purpose, the armature  191  can be designed, for example, as an electrically controllable electromagnet, and the yoke  190  can be designed as a permanent magnet. Here, the electromagnetic force between the armature  191  and yoke  190  acts against the tensile force of the spring  195  and against a pressure (produced by a pump and acting on the bottom connection opening  120 ) of a medium or coolant. Therefore, the opening and closing of the valve  100  can be controlled via the electromagnetic attraction force or a variation thereof. As represented in  FIG. 1 , even when the valve is in the closed state, a residual distance is provided between the armature  191  and yoke  190  in order, for example, to compensate for component tolerances. 
         [0032]    The valve  100  is distinguished by a robust closing behavior, this being ensured in particular at high temperatures or during changes in temperature and during an associated thermal expansion (volume increase) of the sealing ring  140 . High temperatures can be caused by medium flowing through the valve  100 . In the case of the aforementioned coolant circuit of a motor vehicle, the coolant used can heat up, for example, to a temperature of about 110° C. 
         [0033]    To achieve a reliable closing behavior, the valve  100  has, in the region of an outer side of the sealing ring  140 , that is to say a (radially) outwardly directed side, a lower cavity  131  adjoining the lower sealing ring portion  141  and an upper cavity  132  adjoining the upper sealing ring portion  142 . The cavities  131 ,  132  offer a clearance for a temperature-induced radial deformation of the sealing element  140 , with the result that, unlike in a conventional valve, an axial expansion of the sealing ring  140  can be largely suppressed. For the lower cavity  131 , a recess or groove which extends (radially) around the housing inner side is formed in the housing  110  in the region of the end stop  115  and is filled by a part of the lower sealing ring portion  141 . This makes it possible (in addition to the use of the spacer sleeve  160 ) to achieve a (partial) fixing of the sealing ring  140 . Here, the lower cavity  131  is bounded by the sealing ring  140  and the inner side of the housing  110 . By contrast, the upper cavity  132  is bounded by the sealing ring  140 , the housing inner side situated opposite the sealing ring  140  or sealing ring portion  142 , and, in addition, a part of the spacer sleeve  160 . 
         [0034]    The lower sealing ring portion  141  is additionally provided on its outer side with a peripheral sealing lip  149  which bears against the inner side of the housing  110 , in order to ensure a high degree of leaktighness of the valve  100 . In this way, the lower cavity  131  is subdivided into two “sub-cavities”. In addition, or as an alternative, such a sealing lip can also be provided (not shown) on the upper sealing ring portion  142 . 
         [0035]    As described above, the cavities  131 ,  132  serve to accommodate a part of the sealing ring  140  during a temperature-induced radial expansion. In the schematic detail view of a lower region of the valve  100  of  FIG. 2 , such an expansion is indicated by way of deformations  143 ,  144  of the lower and upper sealing ring portions  141 ,  142 , with the sealing lip  149  having being left out of the representation. Here, the radial deformations  143 ,  144  can be accommodated in the cavities  131 ,  132 , with the result that an axial deformation of the sealing ring  140  occurs to a relatively small extent. 
         [0036]    For illustration purposes,  FIG. 3  shows a bulging or deformation  145  of the sealing ring  140  that occurs during a thermal expansion of the sealing ring  140 . Owing to the spacer sleeve  160 , which bears further outwardly against the sealing ring  140 , the deformation  145  occurs on the upper side in particular in the region of the inner circumference of the sealing ring  140 , thus at a point at which the sealing cone  170  bears (with the valve  100  closed) against the sealing ring  140 . The deformation  145  is associated with an axial expansion A, as is illustrated by way of offset dashed circles. The axial expansion A causes the sealing cone  170  bearing against the sealing ring  140  (and hence the lifting rod  171  and the armature  191  with respect to the yoke  190 ) to be displaced axially, with the result that the residual distance between the armature  191  and yoke  190  is increased. 
         [0037]    Owing to the radial thermal expansion possibility for the sealing ring  140  provided by the cavities  131 ,  132 , the temperature-induced deformation  145 , and hence the axial displacement A, is relatively small in the valve  100 . By contrast, in a conventional valve without cavities, no such radial expansion possibility is provided for a sealing ring, with the result that a substantially larger axial deformation, and hence increase in the residual distance between the armature and yoke, occurs. However, the increase in the residual distance results in a reduction in the electromagnetic attraction force, which, in a conventional valve, can assume such an extent that the valve becomes non-leaktight. 
         [0038]    The effect associated with the use of the cavities  131 ,  132  is illustrated by the following exemplary data, which have been obtained by means of tests and simulations on a conventional valve and on a valve with a structure corresponding to the valve  100  of  FIG. 1 . When heating from room temperature to a temperature of 110° C., an axial expansion occurring in the conventional valve (without cavities) amounted to 0.17 mm, whereas the expansion in the valve equipped with cavities amounted to only 0.06 mm. Such a “minimization” of the axial deformation made it possible to achieve an “increase” in the magnetic force between the armature and yoke of about 1.5N. 
         [0039]    In addition to the provision of a thermal expansion possibility for the sealing ring  140 , the cavities  131 ,  132  of the valve  100  are also suited to reducing, for example, component tolerances (in particular of the spacer sleeve  160 ) and an associated deformation of the sealing element  140 . Owing to the expansion or deformation possibility of the sealing ring  140  that is provided by the cavities  131 ,  132 , it is also possible, if appropriate, for a possible inclination of the sealing cone  170  and lifting rod  171  to be compensated. 
         [0040]      FIG. 4  shows a schematic lateral sectional representation of a further valve  101 , which substantially has the same structure as the valve  100  represented in  FIG. 1 . For details on the mode of operation and on corresponding valve components, reference is therefore made to the above statements. 
         [0041]    The valve  101  has a valve housing  111  with asymmetrically arranged connection openings  120 ,  122 , which housing encloses a hollow-cylindrical interior  105 . Arranged in the interior  105  is an elastically deformable sealing ring  146  which, for fixing inside the housing  111 , is braced by a spacer sleeve  161  against an end stop of the housing  115 . An opening  162  corresponding to the connection opening  122  is provided in the spacer sleeve  161 . The sealing ring  146  has a stepped cross-sectional shape with a lower portion  147  and a narrower upper portion  148 . Likewise provided are a lower and an upper cavity  131 ,  132  on the outer side of the sealing ring  146 , in order to create a radial thermal expansion possibility for the sealing ring  146  and consequently to suppress as far as possible an axial expansion of the sealing ring  146  in a corresponding manner to the valve  100  of  FIG. 1 . 
         [0042]    In contrast to the valve  100 , the housing  111  of the valve  101  does not have a peripheral recess for the lower cavity  131  in the region of the end stop  115 . The lower cavity  131  is therefore bounded by the sealing ring  146  or sealing ring portion  147 , the housing inner side and, in addition, a part of the spacer sleeve  161 . Here, as represented in  FIG. 4 , the sealing ring portion  147  can again have a peripheral sealing lip  149  bearing against the housing inner side. 
         [0043]    Furthermore, the spacer sleeve  161 , or the lower portion of the spacer sleeve  161  that widens in the direction of the sealing ring  146 , is provided on the underside with a step (as seen in cross section), which means that the upper cavity  132  is present only between the sealing ring  146  and the spacer sleeve  161 . The lower step-shaped portion of the spacer sleeve  161  and the stepped shape of the sealing ring  146  make it possible here for the spacer sleeve  161  to bear against the upper side the sealing ring  146  only in the region of the outer circumference and in particular in the region of the inner circumference. As a result, it is possible to effectively avoid the situation in which a temperature-induced longitudinal expansion of the spacer sleeve  161  causes, in the region of the inner circumference, a bulging or axial deformation of the sealing ring  146  that adversely affects the closing behavior. 
         [0044]      FIG. 5  shows a schematic lateral sectional representation of a further valve  102  which, in terms of the structure, largely corresponds to the valves  100 ,  101  of  FIGS. 1 and 4 . For details on the mode of operation and on corresponding valve components, reference is made to the above statements. 
         [0045]    The valve  102  has a valve housing  112  with asymmetrically arranged connection openings  120 ,  122 , which housing encloses a hollow-cylindrical interior  105 . Provided in the interior  105  is an annular, elastically deformable sealing element  150  which interacts with a sealing cone  170 , which is integrally formed on or fastened to a lifting rod  171 , in order to close the valve  102 . The lifting rod  171 , which is mounted displaceably, passes out at an upper side of the housing  112  at which the housing  112  is closed by a connection plate  185  and a sealing collar  180 . At an upper end, the lifting rod  171  is connected to a tension spring  195 . To actuate the valve  102 , a yoke  190  arranged on the housing upper side and an armature  191  fastened to the lifting rod  171  are provided, between which an electromagnetic attraction force can be produced against the tensile force of the spring  195  and against a pressure (produced by a pump and acting on the bottom connection opening  120 ) of a medium or coolant. 
         [0046]    In contrast to the valves  101 ,  102  of  FIGS. 1 and 4 , the annular sealing element  150  of the valve  102  is designed as an O-ring  150 . Here, the O-ring  150  is provided on the “edge” of a step or of a shoulder inside the housing  112  in a region above the connection opening  120 . The O-ring  150  can be realized with relatively small dimensions or with a relatively small volume. Consequently, a temperature-induced expansion (which is approximately proportional to the volume), and hence an axial deformation, are also relatively small. 
         [0047]    Furthermore, the use of the O-ring  150  offers the possibility of a fastening without a spacer sleeve, which means that problems associated with a spacer sleeve can be avoided, such as, in particular, a component tolerance and a temperature-induced longitudinal expansion by means of which a sealing element or ring can be (axially) deformed. For reliable and stable fixing, the O-ring  150  is preferably produced together with the housing  112  by carrying out a two-component injection molding process. Here, for example, an elastomer is used for the O-ring  150  and a thermoplastic is used for the housing  112 . 
         [0048]    To illustrate the use of the O-ring  150 ,  FIG. 6  shows a thermal expansion of the O-ring  150  and the axial component A thereof (indicated by way of offset dashed circles). By means of tests and simulations on a valve having a structure corresponding to the valve  102  of  FIG. 5 , the axial expansion determined for the respective O-ring when heating from room temperature to a temperature of 110° C. was only 0.02 mm, which is therefore substantially smaller than the deformation of 0.17 mm obtained on a conventional valve (see above). A temperature-induced decrease in the magnetic force between the armature and yoke is therefore substantially avoided. 
         [0049]    The embodiments of valves described with reference to the figures constitute preferred or exemplary embodiments of the invention. Instead of the embodiment described, further embodiments are conceivable which can comprise further modifications of valves, in which cavities are provided on outer sides of annular sealing elements or in which O-ring seals are used. With regard to the provision of outer-side cavities, in particular annular sealing elements are conceivable which can have a different shape (in cross section) than the sealing rings  140 ,  146 . Also, the stated materials of valve components are to be considered as examples which can be replaced by other materials.