Abstract:
A rotary transmission leadthrough is provided with a gas return line, in particular for filling a vehicle fuel tank comprising a rapid-action connection coupling, which is connected to the supply line and to a return line. The supply line and the return line are arranged in a coaxial manner in relation to each other.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The invention relates to a rotary transmission leadthrough with a gas return line, especially for filling a vehicle gas fuel tank, comprising a rapid-action connection coupling which is connected with a supply line and a return line, characterized in that the supply line and the return line are arranged in a coaxial manner in relation to each other. 
   2. Description of the Related Art 
   A secure and quick-connecting transmission of a fluid from a pressure source such as a natural-gas refueling installation to a vehicle is to be achieved with such rotary transmission leadthroughs. Especially important aspects in this respect are the simple and easy-to-use operation, so that even in the case of high refueling pressures of 200 bars and more easy handling is enabled, especially in connection with rapid-action connection couplings. The connection of such couplings may require a high amount of force in the case of large throughput cross sections (e.g. in the case of refueling buses) as a result of the twisting of the connecting hose. Moreover, the control lever can thus be brought to an unfavourable position during the insertion of the coupling, so that single-hand operation is hardly possible. 
   BRIEF SUMMARY OF THE INVENTION 
   In order to remedy such problems, a rotary transmission leadthrough in conjunction with a rapid-action connection coupling was described in WO 98/05898 of the applicant, with the rapid-action connection coupling comprising a housing with a fluid inlet and a fluid outlet and several valves in order to ensure secure sealing of the rapid-action connection coupling until the connection has been fully established. For compensating the twisting of the connecting hose a rotary transmission leadthrough was proposed which is integrated in the rapid-action connection coupling and also comprises a gas return via a second line. The lines proposed therein are relatively complex from a constructional viewpoint because respective connections such as union nuts and the like need to be provided on the rotary transmission leadthrough and on the hose side. 
   BRIEF SUMMARY OF THE INVENTION 
   The invention is therefore based on the object of providing a rotary transmission leadthrough with gas return line of the kind mentioned above, especially for use in a rapid-action connection coupling, which in combination with a simple configuration offers an especially compact design. 
   This object is achieved by a rotary transmission leadthrough with a gas return line comprising a rapid-action connection coupling which is connected with a supply line and a return line, characterized in that the supply line and the return line are arranged in a coaxial manner in relation to each other. 
   The proposed rotary transmission leadthrough with a gas return line is especially suitable for use with a rapid-action connection coupling for refueling with gas, with an especially simple and compact configuration being obtained because the return line is arranged in a coaxial manner to the supply line and thus only one hose is visible. When connecting or detaching the rapid-action connection coupling, mutual twisting of the connection hose and the gas return line is securely prevented, especially for the preferred embodiment of the invention for filling vehicle gas tanks. 
   Moreover, the screw joints of the supply line are advantageously within the return line and are thus securely encapsulated, so that in the event of any occurring leakages in the high-pressure screw joints or the supply line any gas leaking by diffusion can securely be removed within the return line. This is especially important for reasons of environmental protection because thus no gas volume is lost. 
   Moreover, handling is also facilitated because the supply line as well as the gas return line are uncoupled from each other in the direction of torsion, so that no excessive application of force is required. Notice must be taken that the proposed rotary transmission leadthrough is suitable for a large variety of couplings and connections. The rotary transmission leadthrough can also be arranged as a part for retrofitting, especially for long supply lines in the form of a separate component. 
   As a result of the rotary sleeve which is preferably integrated in the rapid-action connection coupling, complete rotational mobility of the rapid-action connection coupling is thus achieved relative to the supply line at any pressure level, so that twisting of the connection hose and the coaxial gas return line is avoided. The relative twistability of the two coaxial sleeves relative to each other is ensured, so that the rapid-action connection coupling can be connected without any major application of force. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     An embodiment of the invention is now explained and described in closer detail by reference to the enclosed drawings, wherein: 
       FIG. 1  shows a side view of a partially shown rapid-action connection coupling with an integrated rotary transmission leadthrough and a gas return line in a half-section, and 
       FIG. 2  shows a modified embodiment of the supply line. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1  shows a preferred embodiment of a rotary transmission leadthrough  10  for use in combination with a rapid-action connection coupling  1  indicated on the left side here, which coupling can be coupled to a connection nipple (not shown). The rapid-action connection coupling  1  comprises a tubular housing  11  with a central fluid passage (see double arrow), with the supply of fluid occurring here from the right via a supply line  12  which is used for further conducting the fluid to be transferred to the left to the connection nipple. The supply line  12  comprises a connection adapter  14  which is pressed and/or screwed onto the hose end of the supply line  12 . A high-pressure screw joint  25  is adjacent thereto, which joint leads to a rotary sleeve  24  and is sealed accordingly within the rotary transmission leadthrough  10 . The tubular supply line  12 , the connection adapter  14 , the screw joint  25  and the rotary sleeve  24  inserted into the rotary transmission leadthrough  10  are arranged accordingly by being adapted to the respectively transmitted fluid, especially to the desired supply pressure values, leadthrough cross sections, etc. 
   Several grips (not shown) which are arranged in tubular form are provided in housing  11  and are used for insertion on the connection nipple in order to latch the rapid-action connection coupling  1  to the same. This arrangement is shown for example in the aforementioned WO 98/05898, so that a further description can be omitted. It merely needs to be mentioned that within the housing  11  a venting passage E in the form of an axial venting bore  13  is arranged within the housing  11 , which venting passage leads to a vent valve and extends parallel to the central fluid passage (cf. double arrow) of the rapid-action connection coupling  1 . An annular collar  26  is further provided on the rotary sleeve  24 , which collar can be twisted relative to the housing  11  by means of a slide disk  29  and/or a roller bearing (cf.  FIG. 2 ). A counter-sleeve  27  rests on the other face side of the annular collar  26  which is clamped with a union nut  28  against the housing  11 . A ring  30  is provided around said union nut  28  which on its inside circumference comprises several axially extending slits  31 . 
   When the vent valve is now opened for uncoupling, gas flows for pressure reduction along the vent passage E via the vent bore  13 , an intermediate or compensating cavity  18 , the said slits  31  and an annular cavity  38  to the right to the recirculation R, as is indicated with the dot-dash line. The annular cavity  38  is sealed like the entire vent passage E by gaskets  16  and  17  to the outside, so that the gas can only flow into the annular gap between the supply line  12  and the coaxial return line  42  to recirculation R (e.g. a filling station). 
   The return line  42  is held within the union nut  39  which seals the annular cavity  38  and comprises a connecting adapter  39  which is preferably arranged as a press fitting in order to ensure high tensile and tearing strength of the return line. As a result, relatively high gas pressures can be realized towards the recirculation side R. This is especially advantageous when the high-pressure screw joint  25  or the supply line  12  should have a leak. In this case, any optionally leaking gas can be removed within the return line  42  and cannot escape to the outside. 
   When fluid is supplied, the pressure can be applied to the face side of the rotary sleeve  24  or the slide disk  29  which face here to the left, so that a considerable axial force on the rotary sleeve  24  would be obtained in the case of high pressure values. For compensating purposes, a leadthrough (not shown) from the compensating cavity  18  is provided here within the rotary leadthrough  10 , preferably in the form of an oblique or radial bore, so that the rotary sleeve  24  remains substantially free from axial forces and thus easy to twist. 
   As mentioned above, the vent valve is opened during the uncoupling of the rapid-action connection coupling  1 . As a result, any still applying pressure medium flows via the vent bore  13  which is aligned parallel to the central fluid passage in the housing  11  or the rotary leadthrough  10  and the slots  31  (or similar bores) and the annular cavity to the return line  42 . The annular cavity  38  is sealed by gaskets  16  in the corner region for example between the connecting adapter  40  and the union nut  39 . The rotary sleeve  24  connected to the supply line  12  can be twisted relative to each other like the return line  42  and is connected relative to the stationary housing  11  in a twistable manner within the rotary leadthrough  10 , so that the return line  42  and the fluid line  12  extending parallel thereto cannot twist with each other. 
   Notice must be taken that the rotary transmission  10  which is integrated here in the rapid-action connection coupling  1  can also be arranged as a separate component, especially a part for retrofitting existing couplings. In this case, the rotary leadthrough  10  for the two lines  12  and  42  extending coaxially relative to each other would end approximately along the compensating cavity  18 , with the housing  11  situated opposite of the rotary sleeve  24  then being provided with a separate line connection. 
   As already mentioned above, relatively high pressure values can be realized in the return line  42 , so that the modified arrangement according to  FIG. 2  is also possible, i.e. the two lines  12  and  42  extending coaxially relative to each other can be used in a reverse manner in their direction of flow. In this case, the return conduction of the vented medium occurs towards the recirculation side R via the central line  42 , whereas the supply from the filling side which is to the right in this case occurs via an oblique bore Z in the supply line  12  which is arranged here in an annular manner about the line  42 . The pressure medium is guided from there again via an oblique bore Z to the central fluid passage in the region of the rotary sleeve  24  in order to open into the connection coupling  1  according to the double arrow in  FIG. 1 . Components with the same function are provided with identical reference numerals as in  FIG. 1 . 
   Venting occurs in  FIG. 2  as in  FIG. 1  via vent bores  13  and an annular cavity  38  around the rotary sleeve  24 . In this region of the rotary leadthrough  19 , i.e. within the ring  30 , an oblique bore E is provided which guides the vented medium into the central return line  42 . At the severing point indicated here between the right and left half of the high-pressure hose, the direction of the flow of the medium is indicated with arrows. Such a high-pressure hose can have a length of several meters. At the right side here (filling station side), an adapter A is attached, with the return line  42  leading again via a (second) oblique bore E in adapter A to the recirculation side R. Notice must be taken that a similar adapter A can also be attached to the right hose end of the coaxial lines  12  and  42  of the embodiment in  FIG. 1 . The outer covering hose is thus used in both embodiments also for the protection of the coaxial central line. The annular cavity around the central line can be used either for supplying as well as for removing in a controlled manner the gases on the recirculation connection R of adapter A.