Abstract:
The invention is directed to a valve stem system ( 1 ) for tubeless wheels. The valve stem system ( 1 ) includes a valve stem body ( 2 ) with a first end ( 3 ) and a second end ( 4 ), wherein the second end ( 4 ) is located in a tire/rim-volume when mounted at the wheel. A first valve element ( 5 ) is arranged at the second end ( 4 ) of the valve stem body ( 2 ). The first valve element ( 5 ) is a self-sealing one-way valve. The invention further concerns a probe ( 30 ) for a valve stem system, a method to test the amount of sealant in a wheel and a refilling assembly ( 80 ) for a wheel.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    Field of the Invention 
         [0002]    The present invention is directed to a valve stem system e.g. for bicycle wheels, in particular for tubeless wheels. 
         [0003]    Discussion of Related Art 
         [0004]    WO 2010/009887 relates to a device for filling air tires, particularly bicycle tires, with a tire sealing fluid through the valves of the tires. The device is configured as an adapter set having a connector for the tire fluid, and having multiple individual parts which can be inserted into one another, and onto the valves by means of inserting, clipping, and/or screwing, which can be varied with respect to one another depending on the valve type, such as Dunlop valves, Quick valves, or Sclaverand valves. 
         [0005]    US 2006/0021472 relates to a device for injecting tire sealant fluid into a tire. A syringe type reservoir is connected to a long, flexible tube which is in turn connected to a valve stem connector. The valve stem connector has two different threads, Schrader and Presta, to accommodate both types of valve stems. The Schrader type threads are larger than the Presta type threads and thus the Presta type threads are positioned further into the valve stem connector. The larger Schrader type threads are used on automobiles and less expensive bicycles. The tire sealant injector can be used on bicycles, utility vehicles and even automobiles. 
         [0006]    In the prior art, valve stems for tubeless wheels normally have a valve stem body and a valve stem core, which is arranged inside of the valve stem body, as well as a lock nut to secure the valve body on a wheel&#39;s rim. The valve stem body is sealed with the valve stem core. 
         [0007]    In tubeless wheels often a sealant (also called sealing liquid, sealing agent or sealing fluid) is used to improve gas/air tightness of the wheel. In order to maintain gas tightness over time, a tubeless wheel always has to contain a minimum amount of sealant. Due to dehydration, diffusion and leakage the amount of sealant usually decreases over time. However it is still unclear how the amount of sealant in an inflated tire can accurately be determined and/or adjusted. 
         [0008]    It is an object of the present invention to provide a valve stem system and a method to operate such a valve stem system, which avoids the problems known from the prior art. 
       SUMMARY OF THE INVENTION 
       [0009]    The invention provides a valve stem system for a wheel, especially a wheel with a tubeless tire attached to a rim. 
         [0010]    In principle the valve stem system comprises a normally tubular valve stem body with a first end and a second end. In a mounted position the valve stem body extends across the rim wherein the second end of the valve stem body is located in the tire/rim-volume and the first end is arranged outside. 
         [0011]    In a variation of the invention a special first valve element is arranged at the second end of the valve stem body and hence also at least partially located in the tire/rim-volume, when the valve stem system is mounted on the wheel. The first valve element is a self-sealing one-way valve (it may also be called a self-sealing check valve) which is operable although a sealant is present. 
         [0012]    A valve stem system according to the present invention allows to insert a measurement device, or other type of device, from outside into the first end of the valve stem system and protrude the valve stem body and subsequently also the first valve element until the measurement device at least partially reaches the tire/rim-space, while the tire essentially still being inflated without substantial loss of pressure. The measurement device may e.g. be a probe, such as a test tube or rod. According to the invention, the first valve element prevents or limits the escape of pressurized air from the tire/rim-volume prior to the insertion as well as during and after the insertion of the measurement device. Hence in contrast to the valve stem systems known from the prior art, a measurement device can be inserted into the tire/rim-space without first having to remove all pressure-maintaining elements of the valve, such as a valve stem core. Hence pressure in the tire/rim-space can essentially be maintained when a measurement device is inserted. Such a valve stem system according to the invention can also be used to add sealant to or remove sealant from the tire/rim-space, while the tire still being under pressure. 
         [0013]    Embodiments of the first valve element will be explained herein after in more detail. 
         [0014]    In some embodiments, the first valve element may have at least one sealing lip and at least one slit. By displacing or deforming the at least one sealing lip, the at least one slit may be opened or, vice versa, closed. Said sealing lip may preferably be formed and arranged such that the gas pressure gradient between inside and outside of the tire/rim-space exerts a force on the sealing lip. A higher pressure inside of the tire/rim space than outside will typically result in a tighter closing of the slit, while a higher pressure outside of the tire/rim-space will result in an opening of the slit. The latter may e.g. be the case when inflating a tire. 
         [0015]    For some applications, the first valve element may have at least two sealing lips and at least one slit, the sealing lips extending in converging relationship to each other. Thus a particularly good sealing may be obtained. 
         [0016]    In some embodiments, the first valve element may comprise a duckbill-type valve, hence have at least two sealing lips and one slit. The two sealing lips may be shaped symmetrically to each other with respect to a plane of symmetry defined by the slit. This allows an improved closing and opening of the slit as well as increased prevention of leakage of pressurized air when protruding the first valve element with a measurement device, respectively probe. 
         [0017]    In some embodiments, the first valve element is integrally formed and comprises an outer sealing face which can be used to seal the gap between valve stem body and the opening where the valve stem protrudes the rim. 
         [0018]    The first valve element may be made of at least one elastic material, such as a rubber or a silicone material or a similar material. However, the invention is not limited to this selection of material and also other materials or a combination of different materials can be used for the first valve element. In some embodiments of the invention the first valve element may be integrally made in an injection molding process. 
         [0019]    In some embodiments, the valve stem system may further comprise at least one annular sealing element arranged at the second end and inside of the valve stem body or inside of the first valve element. The annular sealing element may be integrally formed at the first valve element which will simplify the assembly and consequently reduce the production cost of a valve stem system. However it may also be separated from the first valve element. Said annular sealing element has an inner diameter which is slightly smaller than the outer diameter of a measurement device, respectively probe, which will protrude the first valve element. Hence it may provide additional sealing against leakage of air during the insertion of a measurement device or probe. In particular it will reduce the escape of pressured air at the moment e.g. a probe or measurement device starts to protrude the first valve element and e.g. the slit of a duckbill-valve starts to open. However the inner diameter of the annular sealing element should not be too small, so that other elements can be arranged or injected inside the valve stem. 
         [0020]    Alternatively or in addition at least one annular sealing element may also be arranged at the first end of the valve stem body and/or between the first and the second end of the valve stem body and having an inner opening of diameter d. 
         [0021]    Alternatively or in addition a measurement device comprises a sealing element that hinders the escape of air from the rim/tire space when being the measurement device is inserted in the valve stem body. Such a sealing element may be an annular sealing element arranged on the outer surface of the measurement device. 
         [0022]    Hence in a valve stem system according to the invention it is possible to insert a probe into the valve stem through the first valve element into the tire/rim-space for determining the amount of sealant present. In a variation of the invention it is further possible to fill new sealant or remove surplus sealant through the valve stem and the first valve element into the tire without deflating the tire, as will be explained in further details below. 
         [0023]    In some embodiments of the invention a second valve element may be arranged in the valve stem for example, to provide a further sealing or to ease deflating the tire. Such a second valve element may e.g. be any type of valve stem core known from the prior art, such as a Schrader-type or Presta-type core. The second valve element may be operatively connected to the first valve element. In some embodiments, the second valve element is operatively connected to the first valve element by a venting element which extends through the valve stem body and is able to open the first valve element. This has the advantage, that the tire can be deflated directly by operating the second valve element without additional means. Such operative connection may e.g. be obtained using a tube-shape venting element, which can be inserted into the valve stem body and which will open the first venting element, e.g. open a slit, when being pressed against it. A tubular venting element therefore may comprise at least one venting opening arranged on a sidewall, so that the air flowing into the inside of the venting element can flow through the venting opening into the valve stem body. 
         [0024]    In a variation of the invention the valve stem body may have a low length if compared to conventional valve stem systems in order to obtain a valve stem system with a particularly compact design. Such a variation may be advantageous in order to prevent damage to the valve stem system (e.g. by vandalism) and/or for aesthetic purposes. Such a variation becomes possible as a second valve element may be omitted due to sealing as provided by the first valve element. 
         [0025]    A further advantage of the valve stem system according to the invention is that the first valve element prevents leakage of pressurized air out of an inflated tire while allowing high flow rates into the tire. Such high flow rates are required for the initial inflation of tubeless tires. In the systems known from the prior art, a second valve element usually has to be removed from the valve stem prior to the initial inflation, in order to get sufficient air flow rates. After the inflation, the second valve has to be screwed into the valve stem again almost instantly in order to prevent critical depressurizing. This procedure requires fast response and skillful handling. Thanks to the first valve element according to the invention, such depressurizing after initial inflation is avoided and hence a second valve element (if needed) can be positioned without haste. 
         [0026]    If appropriate the first valve element may form a thickening at the second end of the valve stem body such that the outer diameter of the first valve element is greater than the diameter of the valve stem body. Thus the outer surface of the first valve element may be used in order to obtain sealing between the valve stem system and the rim. Good results may be obtained if the first valve element comprises a conical or pyramidal (or similarly shaped) outer face. With such a variation, proper sealing contact with the periphery of the valve bores of many types of rims can be established. Therefore a wide range of wheels/rims may be easily retrofitted with such a variation of a valve stem system. Alternatively or in addition, the first valve element may be designed to precisely fit the interior profile of a specific rim, respectively valve bore. 
         [0027]    Alternatively or in addition, the valve stem body may be designed in order to establish a sealing contact with the rim. 
         [0028]    In addition, the first valve element usually will prevent sealant from entering into the valve stem. In the valve stem systems known from the prior art, such pollution of the valve stem regularly causes malfunctions of the valves due to so-called valve clogging. 
         [0029]    In some embodiments of the invention, the valve stem system may also comprise an end cap. Such an end cap may protect the inner part of the valve stem body from pollution. Alternatively or in addition it may also provide additional protection from leakage of pressurized air. The cap may e.g. be screwed onto the valve stem body or onto a second valve element (if present). 
         [0030]    In order to determine the amount of sealant inside of the tire/rim-space, according to the invention a special probe may be provided. Said probe comprises a tubular element and a rod. Said tubular element is made of an at least partially optically transparent material and has a first tube opening at a first tube end and a second tube opening at a second tube end and a tube wall. The rod has a first rod end and a second end. The second rod end is moveably arranged in the tube and can move from a first position to a second position. The distance from the second rod end to the second tube end is in the second position greater than it is in the first position. An orifice is provided in the tube wall. There is an essentially continuous opening between the orifice and the second tube end when the second rod end is at the second rod position. The essentially continuous opening between the orifice and the second rod end is disrupted when the second rod end is at the first rod position. 
         [0031]    By furnishing the tubeless wheel with a valve stem system according to the present invention and applying the probe, the remaining amount of the sealant in the tire can be easily and precisely tested without releasing the air pressure or even removing the tire. The probe is made long enough to reach to the bottom of the tire through the valve stem body and the first valve element. The orifice should be arranged at a proper position in the tube wall, at least higher than the minimum sealant level in the tire, when the probe is inserted in the sealant and the second tube end reaches the bottom of the tire. Hence it can be determined if a tire contains a pre-defined minimum amount of sealant. Good results may be obtained if the orifice is arranged higher than the maximum sealant level as thus a wide range of possible sealant levels can be accurately measured. 
         [0032]    A retaining element may be arranged at the first rod end and stops the moving of the second rod end in direction of the second tube end at the first rod position (p1). The retaining element serves on the one hand as a holding element to hold the rod, on the other hand as a stopper to limit the moving range of the rod in the tube. 
         [0033]    In some embodiments, the rod comprises a first probe sealing element, said sealing element seals the tube in longitudinal direction and is arranged at the second rod end. In some embodiments, the first probe sealing element essentially has a shape of for example, an o-ring or a drop or a bung. However it is not limited to these types of shape. The first probe sealing element may also be a fluid with a high viscosity, such as a grease. 
         [0034]    In some embodiments, a second probe sealing element may be provided and arranged on the rod and located between the first probe sealing element and the first rod end. The second probe sealing element may be an o-ring or a sleeve that is arranged on the rod. The second probe sealing element may also be a fluid with a high viscosity, such as a grease. Such a second probe sealing element helps to prevent pressurized air from flowing through the orifice and tube when the rod is in the first position. 
         [0035]    In some embodiments, at least one probe graduation is marked on the outer surface of the tube. When the tube is made of an at least partly transparent material, the amount of sealant remaining in the probe is visible to the user. By providing the graduation marked on the outer surface of the tube, a precise amount of sealant can be estimated or directly read by the user. Such information may be used in order to determine the amount of supplemental sealant that has to be added in order to obtain an optimum amount of sealant. The amount of sealant to add may e.g. be determined using the graduation in combination with information about the type or geometry of the tire. 
         [0036]    In some embodiments, the rod may comprise means for indicating the first rod position and/or the second rod position so that the user can better control the rod position during sealant level testing. 
         [0037]    In some embodiments, the tube has an outer diameter which is greater than the inner diameter of the annular sealing element to ensure the sealing between the tube and the annular sealing element. 
         [0038]    In some embodiments, the second tube end is tapered, so that protrusion of the tube through the first valve element is improved. In addition a tapered second tube end may prevent sealing between the second tube end and the tire. Thanks to the tapered tube end a gap between the second tube end and the tire is left open when the tube is pressed against the tire and thus tire sealant can flow into the tube. 
         [0039]    A first variation of a method to test the amount of sealant in a wheel furnished with the valve stem system of the present invention, may comprise the following steps: Removing the second valve element, if present; protruding the valve stem body and first valve element with the probe until the second tube end reaches the tire, the second rod end being at the first rod position; moving the second rod end to the second rod position so that the orifice allows an equalization of the air pressure between inside and outside the tube which causes a sealant column in the tube; moving the second rod end to the first rod position; pulling the probe out of the valve stem body; comparing the sealant column with the probe graduation. Thanks to this process the sealant level inside the tube and the sealant level outside the tube become equal in the tire, due to the moving the second rod end to the first position again, the sealant column in the tube subsequently is prevented from moving up or down in the tube. In order to determine the sealant level accurately a wheel will usually first be rotated around its axis of rotation until the valve stem system is at the bottom most position of the wheel. 
         [0040]    As a further aspect of the invention, as an independent inventive concept, a shifting mechanism for a probe is provided, which allows convenient and reliable measurements of the amount of sealant in a wheel. Such a shifting mechanism can be interconnected with the first tube end and with the first rod end of the probe and provides a first configuration in which the rod is in the first position and a second configuration in which the rod is in the second position. 
         [0041]    If desired, such a shifting mechanism may be arranged in a housing which may be connected to the first tube end. 
         [0042]    Good results may be achieved if the shifting mechanism switches from the first configuration to the second configuration when a first external force and/or torque is applied to the shifting mechanism. Thus leveling of the column in the probe&#39;s tube can be initiated. Therefore the shifting mechanism may comprise at least one button which can be pressed in order to apply a force. Alternatively or in addition the shifting mechanism may comprise a twisting element which can be turned in order to apply a torque. 
         [0043]    Good results may be achieved if the shifting mechanism switches from the second configuration to the first configuration when the external force and/or moment is removed. Consequently the sealant column in the tube is prevented from moving up or down in the tube. 
         [0044]    For some applications the shifting mechanism may also switch from the second configuration to the first configuration when a second external force and/or torque is applied to the shifting mechanism. 
         [0045]    A simple and reliable shifting mechanism may be achieved using a spring element, as will be described in further detail below. 
         [0046]    A first variation of a filling, respectively refilling, assembly for a wheel furnished with the valve stem system of the present invention comprises a syringe, a check valve, an extension element and an applicator element. The applicator element can be inserted into the valve stem body until it opens the first valve element. The syringe comprises at least one syringe graduation. In some embodiments of the invention, the applicator element may have an outer diameter which is greater than the inner diameter of an annular sealing element, if present. 
         [0047]    A particularly user friendly filling/refilling assembly may be obtained if the extension element is flexible, hence may e.g. be made from an elastic material. 
         [0048]    A further independent inventive concept relates to another variation of a filling, respectively refilling, assembly for a wheel with a tubeless tire. Such a refilling assembly comprises a syringe, a stopcock (faucet), an extension element (such as e.g. a hose or tube) as well as an applicator element. In such a variation of the invention, the stopcock can be switched from a closed state, when no fluid can pass the stopcock, to an open state, when fluid can pass the stopcock. Thus the stopcock allows to control when sealant is able to flow from the tire/rim space to the syringe and vice versa. The applicator element may be long enough to be inserted through the valve stem body until it reaches the tire. In such a variation of a refilling assembly, the sealant may be (at least partially) transferred from the tire/rim space into the syringe in order to determine the total amount of sealant as well as to allow for visual and/or mechanical and/or chemical analysis of the sealant. Good results may be obtained if the end of the applicator element that gets in contact with the tire is tapered, such that when the applicator element is pressed against the tire, a gap remains open and thus tire sealant can flow into the applicator element. Depending on the type of sealant used, the applicator element&#39;s tube may have a relatively large inner diameter which allows relatively high flow rates even for viscous sealants. After (at least partial) removal of the sealant, additional and/or new sealant may be injected into the tire/rim space again. 
         [0049]    Due to the stopcock, the syringe may be disconnected from the applicator element, while the applicator element is still inserted in the valve stem system, respectively the rim/tire space, without significant loss of pressurized air taking place. 
         [0050]    Good results may also be obtained using a stopcock that is a three or four way valve. Thus not only sealant, but also pressurized air may be provided by the applicator element. 
         [0051]    It will be appreciated that a valve stem system as described above is an independent inventive concept which is useable for tubeless wheels without using a probe and/or filling/refilling assembly as described above. The same holds true for the filling/refilling assembly as well as the probe and shifting mechanism, which all can also be considered as being separate, independent inventive concepts. 
         [0052]    As a further aspect of the invention, as an independent inventive concept, a syringe may be used in order to store several components of a refilling assembly. Therefore the space between the plunger, plunger head, barrel and thumb rest (of the plunger), which in normal syringes usually is void, is used in order to store some components, e.g. a valve stem system and/or an applicator elements and/or a stopcock and/or an extension element. Hence all components needed to fill, control and/or refill sealant can be stored safely. 
         [0053]    Good results may be achieved if the plunger comprises holding means upon which a check valve and/or a stopcock and/or the extension element and/or applicator element may be securely fastened to the plunger. 
         [0054]    For some purposes, the space between the plunger head, barrel and thumb rest may be divided into several compartments, which may be specifically shaped in order to receive the components that have to be stored. 
         [0055]    In a variation of this aspect of the invention, a refilling assembly is provided, the syringe and/or check valve and/or a stopcock and/or the extension element and/or applicator element are dimensioned such that the check valve and/or a stopcock and/or the extension element and/or the applicator element can be stored at least partially within the space between the plunger and the barrel of the syringe. 
         [0056]    Alternatively or in addition, also one or multiple valve stem systems may be stored within the space between the plunger and the barrel of the syringe. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0057]    The herein described invention will be more fully understood from the detailed description of the given herein below and the accompanying drawings, which should not be considered as limiting to the invention described in the appended claims. 
           [0058]      FIG. 1  shows a valve stem system mounted on a rim; 
           [0059]      FIG. 2  shows a valve stem system; 
           [0060]      FIG. 3  shows a section view of a valve stem body and a first valve element; 
           [0061]      FIG. 4  shows a section view of a valve stem body and a first valve element; 
           [0062]      FIG. 5  shows a valve stem system with a second valve element mounted; 
           [0063]      FIG. 6  shows a cross-cut through the valve stem system with a second valve element of  FIG. 5  along line A-A; 
           [0064]      FIG. 7  shows a section view of a valve stem system with a second valve element mounted; 
           [0065]      FIG. 8  shows a valve stem system and a second valve element; 
           [0066]      FIG. 9  shows a section view of a valve stem system mounted on a rim; 
           [0067]      FIG. 10  shows a probe for a valve stem system; 
           [0068]      FIG. 11  shows a cross-cut through the probe of  FIG. 10  along line B-B; 
           [0069]      FIG. 12  shows detail C of  FIG. 10 ; 
           [0070]      FIG. 13  shows detail D of  FIG. 11 ; 
           [0071]      FIG. 14  shows a section view of a probe inserted in sealant; 
           [0072]      FIG. 15  shows detail D of  FIG. 14 ; 
           [0073]      FIG. 16  shows detail E of  FIG. 14 ; 
           [0074]      FIG. 17  shows a section view of a probe inserted in sealant; 
           [0075]      FIG. 18  shows a section view of a probe inserted in sealant; 
           [0076]      FIG. 19  shows a section view of a probe; 
           [0077]      FIG. 20  shows detail F of  FIG. 19 ; 
           [0078]      FIG. 21  shows detail G  FIG. 19 ; 
           [0079]      FIG. 22  shows a refill assembly; 
           [0080]      FIG. 23  shows a valve system; 
           [0081]      FIG. 24  shows the valve system in partially disassembled state; 
           [0082]      FIG. 25 a    shows a refilling assembly; 
           [0083]      FIG. 25 b    shows cross-section H-H of  FIG. 25   a;    
           [0084]      FIG. 26  shows the refilling assembly of  FIG. 25 a    partially disassembled; 
           [0085]      FIG. 27  shows the plunger and the components stored in it; 
           [0086]      FIG. 28  shows a refilling assembly in a first state; 
           [0087]      FIG. 29  shows a refilling assembly in a second state; 
           [0088]      FIG. 30 a    shows a probe in a perspective view; 
           [0089]      FIG. 30 b    shows the probe of  FIG. 30 b    in a front view; 
           [0090]      FIG. 31  shows the probe of  FIG. 30  in a first state in a back view and broken view, the second tube end being partially removed for illustrative purposes; 
           [0091]      FIG. 32  shows the probe of  FIG. 31  in a second state; 
           [0092]      FIG. 33  shows detail I of  FIG. 30 ; 
           [0093]      FIG. 34  shows detail J of  FIG. 31 ; and 
           [0094]      FIG. 35  shows detail K of  FIG. 32 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0095]      FIG. 1  shows an embodiment of a valve stem system  1  mounted on a wheel rim  50  including with a tire  60  mounted, in particular a tubeless wheel. The tire  60  is filled with sealant  70  for sealing the tire. The valve stem system  1  protrudes outward the outer (centripetal) surface of the rim and is fastened at the rim  50  using a nut  14 . 
         [0096]      FIG. 2  shows an embodiment of a valve stem system  1  comprising a tubular valve stem body  2  and a first valve element  5 . The valve stem body  2  has a first end  3  and a second end  4  connected by a passageway which extends in longitudinal direction through the valve body  2 . A cap  15 , which can be threaded at the first end  3  of the valve stem body  2 , is provided. The cap  15  protects the inner volume of the valve stem body  2  from pollution as well as it may serve as an additional sealing element to prevent the passage of pressurized gas through the valve stem body  2 . The first valve element  5  is arranged at the second end  4  of the valve stem body  2 , hence it is arranged at the base of the valve stem system  1 . The first valve element  5  comprises an outer sealing face  8  as well as sealing lips  6 . The two sealing lips  6  form a half-spherical essentially convex shape. In between the two sealing lips  6  there is the valve opening, which in this embodiment is a slit  7 . The slit is in a closed state when the two sealing lips  6  are in contact. The sealing lips  6  extend in converging relationship to each other leading to an opening of the slit  7 . On its outer surface, the valve stem body has an outer thread  13  which can be used to fasten the cap  15  or attach the valve stem system  1  to a rim e.g. by a nut. 
         [0097]      FIG. 3  and  FIG. 4  show two embodiments of a first sealing element  5  of the valve stem system. The first valve element  5  is mounted at the second end of the valve stem body by means of an interlocking and/or a glued connection. The outer sealing surface  8  has a tapered shape and is essentially in parallel to a tapered part of the outer surface of the valve stem body  2 , which allows for a mechanically advantageous load transmission between valve stem body  2  and rim  50  when mounted. As shown e.g. in  FIG. 3 , the sealing lips  7  may also have a rather limited extension in longitudinal direction of the valve stem system, resulting in the first sealing element  5  having a rather compact shape. A first sealing element  5  with such a shape may be less exposed to e.g. impacts on the tire resulting from curbs, stones or potholes. 
         [0098]    Using a first valve element  5  with convex sealing lips  6  helps to increase sealing of the slit  7 . As shown in  FIG. 4 , the gas pressure in the tire/rim space acting on the outer surface of the sealing lips  6 , schematically indicated with arrows P+, causes an increased contact force between the two sealing lips  6 , schematically indicated with arrows r. This causes a higher contact pressure between the faces inside of the slit  7  and hence a tighter closure of the slit  7 . As shown in  FIG. 4 , an additional sealing element  9  may be arranged at the second end of the valve stem body. As shown in  FIG. 4  the additional sealing element may have an annular shape and may be part of the first valve element  5 , hence be integrally formed with the first valve element  5 . In contrast to  FIG. 4 ,  FIG. 3  shows an embodiment without such an annular sealing element  9 . 
         [0099]      FIG. 5  shows one embodiment of the valve stem system ( 1 ) with a second valve element  10  mounted removably at the first end  3  of the valve stem body  2 , partially housed within the valve stem body  2 . The second valve element comprises a core rod  16 , a core nut  17  and a bushing  18 . The second valve element  10  may be connected to the valve stem body  2  using a thread, as shown in  FIG. 6 . The assembling of the core rod  16 , the nut  17  and the bushing  18  may be according to, or similar as for Presta-type or Schrader-type valve cores.  FIG. 6  is a cross cut of  FIG. 5  along line A-A. As can be seen, the core rod  16  has a first end and a second end. In mounted state, said first end may protrude outside of the first end  3  of the valve stem body  2 , the second end is located inside of the valve stem body  2 . A venting element  11  is arranged at the second end of the valve stem body  2 . As shown in  FIG. 6 , the venting element  11  may have a tubular shape, comprising one or multiple venting openings  12  in its sidewall. Being mechanically operatively connected to the core rod  16 , the venting element  11  serves as an extension of the core rod  16 .  FIG. 7  shows the valve stem system  1  of  FIGS. 5 and 6  when inflating or deflating a tire. Therefore the second valve element  10  is unlocked by screwing off the core nut  17 , as known e.g. from Presta-type valve cores. After that, the core rod  16  can be shifted towards the first valve element  5 , causing the venting element  11  to protrude the first valve element  5  by opening the slit  7 , resulting in a continuous valve opening between the two ends of the valve stem system  1 . Consequently air can continuously flow from the second side of the valve stem system into the venting element  11 , through the venting opening  12  into the valve stem body  2  and sequentially through the channel between the bushing  18  and the core rod  16  to the first end  3  of the valve stem system  1 , or vice versa in the other direction. 
         [0100]      FIG. 8  illustrates an embodiment of a valve stem system  1  with the second valve element  10  being removed from the valve stem body  2 . 
         [0101]      FIG. 9  shows a section view of the valve stem system  1  when being mounted on the rim. The first valve element  5  is essentially located inside of the rim/tire space, preventing the pressurized air from escaping from the rim/tire space. 
         [0102]      FIG. 10  shows a probe  30  for testing the amount of the sealant  70  in the tire  60 .  FIG. 11  shows a section view of the probe  30 . The probe  30  comprises a tube  31  with a first tube opening  32  at a first tube end  33  and a second tube opening  34  at a second tube end  35  and a rod  36 . The rod  36  has a first rod end  37  and a second rod end  38  as shown in  FIG. 17 . For testing the amount of sealant, the rod  36  is inserted into the tube  31  and is moveable in the axial direction, whereby the second rod end  38  is located inside of the tube  31 . A retaining element  40  is attached to the first rod end  37  as a holding element and as a stopper to prevent the rod  36  from entirely entering into the tube  31 . An orifice  39  is arranged in the tube wall to equalize the pressure inside and outside of the tube. 
         [0103]      FIG. 12  shows that the second tube end  35  may be tapered, so that the probe can easily go through the first valve element  5 . In addition, the tapered second tube end  35  ensures that sealant  70  can flow into the tube  31  when the tube  31  is pressed against the tire  60 . 
         [0104]      FIG. 13 ,  FIG. 16  and  FIG. 21  show the probe  30  with a first probe sealing element  41  and a second probe sealing element  42 .  FIG. 13  shows one embodiment of the probe with the first probe sealing element  41  attached to the second rod end  37  and the second probe sealing element  42  attached to the inner wall of the tube  31 . The second probe sealing element  42  may be a tubular element, which can be arranged on the inner wall of the tube  31 , for example, by gluing. The first probe sealing element  41  may have a shape of drop or bung. The dimension of the first probe sealing element  41  should be adapted to the inner diameter of the tube  31  by considering the production tolerances to ensure the sealing. The first probe sealing element  41  can be made of elastic material. The second probe sealing element  42  may have a tubular shape. The inner diameter of the second probe sealing element  42  may be adapted to the outer diameter of the rod  36  by considering the production tolerances to obtain a further sealing.  FIG. 19  and  FIG. 21  show another embodiment of the probe  30  with the first probe sealing element  41  and the second probe sealing element  42  having a shape of o-ring. In this embodiment, the first probe sealing element  41  is arranged near the second rod end  37  and the second probe sealing element  42  is arranged between the first rod end  36  and the second rod end  37 . However, the arrangement and the shape of the probe sealing elements  41 , 42  are not limited to the variation described above. 
         [0105]    As shown in  FIG. 20 , a mark  45  is formed or marked on the rod  36  with a position being visible to the user. It allows the user to clearly indentify the position of the second rod end  38  relatively to the orifice  39 , when inserted in the tube  31 . 
         [0106]      FIGS. 14 to 17  and  FIG. 18  illustrate the process of testing the amount of sealant  70  in the tire  60 . In a first step, the retaining element  40  is pushed down toward the first tube end  33  to a position, such that the first probe sealing element  41  is moved to a position below the orifice  39  ( FIG. 14  and  FIG. 16 ). The probe  30  is inserted through the slit  7  until the second tube end  35  reaches the tire. Normally, no sealant  70  enters into the tube  30 . In a second step, the retaining element  40  is pulled up such that the first probe sealing element  41  is moved to a position above the orifice  39  ( FIG. 17 ). This can be controlled by the user regarding the mark  45  on the rod  36 . The sealant  70  enters into the tube  30  and a sealant column  44  has the same height as the sealant outside of the tube  30  in the tire. In a third step, the retaining element  40  is pushed down again toward the first tube end  33  to a position, such that the first probe sealing element  41  is moved to a position below the orifice  39  ( FIG. 18 ). Thus the essentially continuous opening between the orifice  39  and the second tube end  35  is closed which prevents the sealant column from being able to move up or down in the tube  31 . The tube  30  can then be removed out of the valve stem body  2  while keeping first probe sealing element  41  staying below the orifice. The amount of the sealant  70  can be read by comparing the sealant column  44  with the probe gradation  43  marked on the outer surface of the tube  30 . 
         [0107]      FIG. 22  illustrates a refilling assembly  80  for a wheel furnished with the valve stem system of the present invention. The refilling assembly  80  comprises a syringe  81 , a check valve  83 , an extension element  84  and an applicator element  85 . The applicator element  85  can be inserted into the valve stem body  2  until it opens the first valve element  5 . The syringe comprises at least one syringe graduation  82 . 
         [0108]      FIGS. 23 and 24  show another embodiment of a valve stem system  1  in assembled, respectively partially disassembled state. As shown, this embodiment of a valve stem system comprises a fist valve element  5  that has multiple sealing lips  6 . 
         [0109]      FIGS. 25 a    to  27  show a refilling assembly  80  which is designed such that its major components can be stored in a compact way. The refilling assembly  80  comprises a plunger  86  which will usually be positioned within a central opening of a barrel  90 , forming a syringe  81 . When the plunger  85  is mounted inside of the barrel  90 , the space defined by the plunger  85 , the plunger head  87 , the plunger&#39;s thumb rest  92  and the barrel  90  is divided into compartments  88   a - c , as can e.g. be seen in  FIG. 25 b   . In the embodiment shown, in a first compartment  88   a  an extension element  84  of the refilling assembly  80  is positioned, together with a stopcock  91  (not visible in  FIG. 25 b   ). In a second compartment  88   b  an applicator element  85  of the refilling assembly  80  is positioned, as can be seen in  FIGS. 25 b    and  26 . In a third compartment  88   c , two valve stem systems  1  are positioned, as can be seen in  FIGS. 25 b    and  26 . Thus such a variation of a refilling assembly may be sold e.g. for retrofitting a bicycle with new valve stem systems  1  together with a compatible refilling assembly  80 . As shown in  FIGS. 26 and 27 , the shape of plunger  86  may be adapted to the shape of the components that are stored in the compartments  88   a - c . Therefore also holding means  89  may be formed in order to establish a snapping connection with the components for secure storage of them. 
         [0110]      FIG. 27  also shows an embodiment of a refilling assembly  80  that comprises a relatively long applicator element  85  that has a relatively large inner diameter and a tapered end (lower end in  FIG. 27 ). In addition, this embodiment of a refilling assembly  80  comprises a stopcock  91  that can be switched from a closed state, when no fluid can pass the stopcock  91 , to an open state, when fluid can pass the stopcock. As shown in  FIG. 28  the stopcock  84  has a first end which can be connected to the syringe  81  and a second end that can be connected to an extension element  84 , which in the embodiment shown is a hose. In  FIGS. 28 and 29  the barrel&#39;s  90  wall has been partially removed for illustrative purposes. As also shown in  FIG. 28 , the extension element  84  can be connected to the applicator element  85  which can be inserted through a valve stem system  1  into a tire  60 . Also in such an refilling assembly  80 , the valve stem system  1  successfully prevents pressurized air from escaping from the tire  60  prior to the insertion of the applicator element  85  as well as afterwards. In the embodiment shown, the applicator element  85  is inserted into the valve stem system  1  and hence the rim/tire space until the applicator element&#39;s  85  lower tapered end gets into contact with the tire  60 . Usually, the stopcock  91  will be in the closed state until this insertion is complete and will then be switched to the open state. Thus the sealant  70  can be transferred to the syringe  81 , resulting in a movement of the plunger  86  relatively to the barrel  90 , as indicated in  FIG. 28  by a dotted arrow. Thus, if wished be the user, essentially all sealant  70  can be removed from the tire  60 , as shown in  FIG. 29 . This transfer may be driven or at least be assisted by the pressurized air in the tire. However it is clear, that the refilling assembly may also be used after the tire/rim space has been depressurized. A complete removal of sealant  70  will usually be indicated by small air bubbles appearing in the extension element  84  (if it is made from an optically transparent material) and/or the syringe. As soon as the sealant  70  is removed, the stopcock  91  can be switched to the closed state and the syringe  81  may subsequently be disconnected from the stopcock  91  in order to allow for a proper inspection of the sealant  70 . Thus by visual, mechanical or chemical means the amount of quality of the sealant  70  can be determined accurately. If needed, the amount of sealant may be adapted and/or it may be replaced by a new sealant  70 . Subsequently the syringe  81  can be connected to the stopcock  91  again and the sealant  70  can be injected into the tire  80 . 
         [0111]      FIGS. 30 a  and 30 b    show an embodiment of a probe  30  for a valve stem system  1  (not shown) which allows particularly convenient measurements. The probe  30  comprises a tube  31  that has a second tube end  35  which can be inserted in a valve stem system  1 . As for the embodiments of probes  30  shown in previous Figures, the tube  31  will usually be made from an optically transparent material. The first tube end (not visible) is arranged in a housing  46 . The housing  46  comprises grip elements  47  which allow a convenient handling of the probe  30 . The housing further comprises a display opening  48  which displays the position of a rod  36  (not shown) that is arranged inside of the tube  31 , as will be explained in further details in  FIGS. 31 to 35 . The housing  46  shown in  FIG. 30 a    further comprises two lateral buttons  52   a ,  52   b  which can be pressed together in order to operate the probe  30 , as will be explained in the subsequent figures. 
         [0112]    In  FIG. 31  the inner shifting mechanism  51  of the housing  46  is shown. The shifting mechanism  51  of the embodiment shown comprises a spring element  53  which in this embodiment essentially has the shape of an omega, the two ends of the spring element  53  being fixedly connected to the housing  46  by anchors  54   a - b . At a midpoint of the spring element  53  the spring element  53  is connected to the first rod end  37  of a rod  36 , said rod being arranged in the tube  31 , in a similar way as e.g. shown in  FIG. 10 to 21 . The spring element  53  is slightly pre-stressed between the anchors  54   a - b  and first stoppers  55   a - b . The spring is also in contact with the two lateral buttons  52   a - b  of the housing. In  FIG. 31  the shifting mechanism  51  is shown in a first configuration, the rod  36  being in a first position, hence the second rod end  38  is in a first distance from the second tube end  35 , an orifice  39  in the tube  31  being sealed by a first probe sealing element  41  and a second probe sealing element  42 , as shown in detail in  FIG. 34 . As shown in  FIG. 33 , in this first configuration, a mark  45  arranged on the first rod end  37  can be seen in the display opening  48  at a first reference mark  49   a , indicating to a user that the rod  31  is in a first position with the orifice  39  being separated from the second tube end  35 . 
         [0113]    As shown in  FIG. 32 , by pressing the two lateral buttons  52   a - b  together (indicated by dotted arc arrows) the shifting mechanism  51  can be switched to a second configuration. Therefore the spring element  53  is laterally squeezed, leading to an elongated shape of the spring element  53  and hence a displacement of the midpoint of the spring element, leading to a displacement of the rod  31  (indicated by the dotted straight arrow). Thus the first rod end  37  can be displaced until it is stopped by a second stopper  56 . At the same time, third stoppers  57   a - b  prevent the two buttons  52   a - b , respectively the spring element  53 , from being deformed any further. Thus the spring being deformed to a maximum and the rod being displaced to a maximum, it is ensured that the rod is in a second position, as shown in  FIG. 35 . At this second position, the mark  45  in the display opening  48  would be at a second reference mark  49   b  (not shown). As shown, the orifice  39  is not separated from the second tube end  35  in this second position, allowing a leveling of the sealant (not shown) inside of the tube  31 . As soon as the two lateral buttons  52   a - b  are not pressed together anymore, the shifting mechanism switches back to the first configuration as the spring element  53  flexes back into its original more circular shape, resulting in the rod  36  moving back to the first position with the orifice  39  being separated from the second tube end  35  again.