Abstract:
A quick connect coupling for transmitting fluids includes a tubular housing and spreadable locking elements fixed on the housing for connection to a correspondingly formed connector. A sealing piston is slidable centrally in the housing for engagement with the connector and surrounded by an axially movable sliding sleeve. The sliding sleeve retains the locking elements in the locking position in the coupled position of the quick connect coupling.

Description:
FIELD OF THE INVENTION 
     This invention relates to a quick connect coupling for transmitting gaseous and/or liquid fluids, especially for filling gas tanks. 
     A reliable, tight and rapidly connected plug-in coupling has to be provided by such quick connect couplings, for transmitting a fluid from a pressure source, for example a refilling cylinder or a pressure tank. Simple, problem-free operation of the quick connect coupling is particularly important, so that problem-free handling is made possible, even under unfavourable conditions, such as with dangerous fluids or high connection pressures. 
     BACKGROUND OF THE INVENTION 
     Such a quick connect coupling is described in EP-A 0 340 879, wherein the quick connect coupling comprises a housing with a fluid inlet and a fluid outlet, as well as a plurality of valves, in order to ensure reliable sealing of the quick connect coupling until the connection is completely effected. These valves are operated after attaching the quick connect coupling in a specific, predetermined sequence, wherein the outlet valve is opened first, then the collet jaws are closed by further movement of a control lever and finally the inlet valve is opened. The control lever engages via an eccentric shaft with the sliding sleeve for actuating the collet jaws and with a central sealed piston, which also opens the fluid inlet after completed attachment of the plug-in coupling. 
     Although a particularly secure connection is provided by this, the structure of this coupling is relatively expensive, on account of the many components. In addition, operation is relatively complex, since the operation of the control lever is necessary in addition to plugging in the coupling, so that single-handed operation is hardly possible. 
     Such a quick connector is further known from WO-A 93/20378 of the applicant, especially for filling gas cylinders, wherein a quick connect device in the form of collet jaws with an engagement profile is provided in the region of the outlet. A hollow sealing piston slidably movable in the coupling housing is also described, being connected trough an actuating device connected to a sliding sleeve for closing and opening the collet jaws. The handling of his quick connect coupling is also open to improvement. Further plug-in couplings are known from EP 0 382 723 and DE 3 518 019 of the applicant, in which similar disadvantages apply, in particular canted attachment of the connection coupling and thus its opening with fluid release with (still) incompletely made sealing connection cannot be completely ruled out. 
     SUMMARY OF THE INVENTION 
     Accordingly the invention is based on the object of providing a quick connect coupling of the kind initially specified which facilitates particularly reliable and simple handling with a simple structure, 
     This object is met by a quick connect coupling for transmitting gaseous and/or liquid fluids. The quick connect coupling includes a tubular housing, spreadable locking elements fixed on the housing for connection to a correspondingly formed connector, and a sealing piston slidable centrally in the housing for engagement with the connector. The sealing piston is surrounded by an axially movable sliding sleeve which retains the locking elements in the locking position in the coupled position of the quick connect coupling. Preferred developments of the invention form the subject matter of the dependent claims. 
     The proposed quick connect coupling is distinguished by simple operation, which is also particularly reliable, since it can be coupled up and uncoupled with hardly any force. This proposed quick connect coupling is suitable for different connectors, especially for connecting nipples of gas tanks and for gas cylinder valves. Through the sealing piston which can slide or telescope in the housing, a more secure engagement of the locking elements, especially of the collet jaws, since the engagement profile of the collet jaws automatically adapts to the corresponding interlocking engagement profile of the complementary connector by virtue of the ability of the sealing piston to slide and the locking elements, especially the collet jaws are locked independently of the sealing piston. This is especially important, since the corresponding connection nipple, e.g. for a gas tank, can be made relatively simple. Because of the ability of the sealing piston to slide axially, a reliable, tight engagement between the engagement profile and the sealing surface at the end surface of the quick connect coupling results and only then does the outlet or check valve coupled thereto open. In particular excessively canted application of the coupling is avoided by this, i.e. the user is constrained to correct fitting, since both the opening of the fluid passage and also the coupling up at the coupling side are otherwise prevented. Wear of or damage to the connecting profile is also reliably avoided through this, on both the coupling and the nipple side. 
     The realisation of the quick connect coupling by means of an outer control sleeve is also especially important, preferably for pneumatic actuation of the coupling, so that a reliable and rapid, one-handed operation of the quick connect coupling is facilitated in an especially simple manner. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     An embodiment will now be explained and described in more detail with reference to the accompanying drawings, in which: 
     FIG. 1 is a side view of a quick connect coupling for a connecting nipple as a connector, wherein the quick connect coupling is shown in longitudinal half section and in the connected position; 
     FIG. 2 shows a modified embodiment of the quick connect coupling, also in the connected position; 
     FIG. 3 shows a further embodiment of the quick connect coupling before connection; and 
     FIG. 4 shows the quick connect coupling according to FIG. 3 in the connected position. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In FIG. 1 there is shown a preferred embodiment of a quick connect coupling  10  with coupling to a complementary connector  30  shown only in part, in the form of a nipple. The quick connect coupling  10  comprises a tubular housing  11 , wherein the right end here serves as the inlet  12  and the left end as the outlet  13  for passing the transmitted fluid on to the connecting nipple  30 . The inlet  12  to the housing  11  comprises a tubular connection adaptor  14 , which is screwed into the housing  11  and has a through passage  14   a  in the form of a central bore. The connection adaptor  14  has a thread  14   b  at its end here on the right, to which a hose or a pipeline can be connected for supplying the fluid to be transmitted. The connection adaptor  14  can be designed to match the fluid to be transmitted, especially the currently desired feed angle, passage cross-section, etc. 
     On the end of the housing  11  remote from the connection adaptor  14 , namely the outlet  13 , a plurality of locking elements are provided, in the form of elongated collet jaws  15 , which are spread radially inwards in the unillustrated position before insertion into the connector  30 . The elongated collet jaws  15 , of which at least three and in general six are arranged round the housing  11 , are hooked into an annular groove  11   a  of the housing  11  at the ends here on the right and are biased by a spring ring  16  so that the collet jaws  15  are spread radially inwards (cf. also FIG.  3 ). The collet jaws  15  comprise interlocking engagement profiles  17  on the outwardly offset surface corresponding to the hook-shaped connection profile  31  of the connector  30  at their end here on the left. 
     Around the collet jaws  15  there is provided an outer sleeve  18 , preferably of plastics material or rubber, which is guided on the cylindrical outer wall of the housing  11 . At the end of the housing  11  at the outlet  13  there is provided a sealing piston  22  which can preferably pivot in all directions by means of a ball joint and which comprises on its front end face a sealing ring  23  for abutment against a tapered sealing surface  32  of the connection nipple  30 . The sealing piston  22  is sealed by means of an inset sealing ring  24 , so that gaseous and/or liquid fluid flowing essentially along the central axis of the plug-in connector coupling  10  cannot escape to the outside. Moreover a compression spring  19 , which is pre-stressed in the direction of the connection nipple  30 . is arranged in the flow path along the through passage  14   a . The compression spring  19  supported by a shoulder  20  on the connection adaptor  14  bears against a valve cone  21  of a check valve  25 . 
     It is important that the check valve  25  mounted centrally on a valve stem in extension of the sealing piston  22  seals by means of a sealing ring  28  relative to a sealing surface  27  on an annular or sliding sleeve  40  in the closed position. The check valve  25  is biased by the compression spring  19 , which is mounted by mean of the shoulder  20  in the connection adaptor  14  and is supported against the latter. Through this check valve  25  and the sealing piston  22  coupled thereto it is ensured that fluid fed through the connection adaptor  14  cannot flow out in the uncoupled position or up to briefly before the connection of the quick connect coupling  10  to the connection nipple  30 , even with the connecting tap on the refilling cylinder or the like open. 
     The check valve  25  has a centrally arranged through passage facing towards the outlet  13  in continuation of the through passage  14   a . After completed connection of the quick connect coupling  10 , with interlocking engagement of the collet jaws  15  through the sliding sleeve  40  or a head piece  40 ′ screwed thereon at the end opposite the connection nipple  30 , this through passage cooperates with the through passage  14   a , whereby the check valve  25  with the sealing surface  27 / 28  is forced into the open position when connection is made. 
     Of particular importance is the annular or sliding sleeve  40  which is guided on the outer periphery of the sealing piston  22  and of the check valve  25  and is biased by at least one compression spring  29 , preferably in a pressure space  27 , inside the housing  11 . The compression spring  29  (cf. also FIG. 3) is supported on a recess of the housing  11  or of the connection adaptor  14 . As can be seen from the drawing, the tapered end of the sliding sleeve  40  or the head piece  40 ′ screwed thereon facing the outlet  13  engages on the inner surface ( 15 ′ in FIG. 2) of the collet jaws  15 , whereby these are retained in their radially spread-out locking position. The sliding sleeve  40  is pushed by the compression spring  29  up to the inwardly offset region of the housing  11 , whereby a stop for the sliding movement of the sliding sleeve  40  is obtained at the sane time. Since the sealing piston  22  with the collect jaws  15  is mounted slidably in the sliding sleeve  40 , the engagement profile  17  can engage in the opposed profile  31  of the connection nipple  30  with especially small coupling force, depending on the engagement conditions. In general the spring force of the compression spring  29  is already enough for this, in order to ensure the closed position here shown with locking of the locking elements, in particular the collet jaws  15 , in independent manner, through axial displacement of the sliding sleeve  40  with the sealing piston  22  mounted therein. 
     In order to facilitate further the manual actuation of the sliding sleeve  40  for the coupling and uncoupling, for example with a manual lever according to the initially recited DE 3 518 019 or an eccentric lever according to EP-A 0 340 879, pneumatic assistance can also be provided by means of an actuating device  50 , an air channel  51 , an air feed sleeve  52  and two annular channels  53 . Through axial movement of the actuating device  50  the air channel  51  is connected in the position here shown through the annular channels  53  to the air feed sleeve  52 , so that a piston face  42 ′ on a piston  42  of the sliding sleeve  40  is affected and this is thereby retracted. In order to increase the pushing force of the sliding sleeve  40  into the locking position, supplementing the compression springs  29 , a piston annular surface  42  (corresponding to the piston surface  22   a  in FIG. 3) can be formed within the housing  11  on the piston  41  with a greater diameter. 
     The quick connect coupling  10  is shown in FIG. 2 in a modified embodiment, wherein the head piece  40 ′ of the sliding sleeve  40 , which can also be formed in one piece, is made somewhat shorter, with otherwise like reference numerals for the same components. A greater ability of the sealing piston  22  to pivot is hereby attained, whereby this piston can also be made in one piece with or rigid relative to the valve stem of the check valve  25 . The outer peripheral surface or the sealing piston  22  or the valve stem of the check valve  25  can also bear directly on the here offset inner surfaces  15 ′ of the collect jaws  15  for locking these. As can be seen, on inserting or plugging on the quick connect coupling  10  into or on to the connector  30 , the end sealing ring  23  on he sealing piston  22  is brought into contact with the connector  30 . The sealing ring  23  thus comes into firm contact with the sealing surface  32 , before the check valve  25  at n the sealing surfaces  27 ,  28  can open, so that escape of fluid which is present on the valve cone  21  of the check valve  25  on the coupling side is avoided. Through the engagement of the sealing ring  23  on the sealing surface  22  the sealing piston  22  is moreover pushed to the right into the open position, while however the sliding sleeve  40  or its head piece  40 ′ or the outer peripheral surface of the sealing piston  22  or the valve stem of the check valve  25  contacts the collect jaws  15  at their inner surfaces  15 ′ and holds them spread out in the locking position. 
     It should be noted that, during this coupling movement, the sealing piston  22  together with the sliding sleeve  40  is first pushed to the right against the spring force of the compression spring  19 , the check valve  25  still being closed. After a small stroke of a few millimetres, the inner surface  15 ′ of the collet jaws  15  bearing on the outer surface of the sliding sleeve  40  or in general of the sealing piston  22  are spread into their blocking position, so that the engagement profile  17  engages with the correspondingly formed connection profile  31  of the connection nipple  30 . The sliding sleeve  40  is practically simultaneously free through this for the axial movement to the left, since the sliding sleeve  40  is also acted on by the compression spring  29 . Through this axial movement of the sliding sleeve  40  and/or of the sealing piston  22 , this/these engage on the inner surfaces  15 ′ of the collet jaws  15  in the manner of a collar, so that these are retained interlocked in their spread, engagement position on the connector  30 . 
     It should be noted that the sealing piston  22  can still move pivotally slightly in the connected position here shown in FIG.  2 . The surface on the valve piston  21 , which has a greater effective surface than in the region of the contact surface between the sealing ring  23  and the sealing surface  32 , is also important. This ensures that, with the flow direction essentially along the central axis of the quick connect coupling  10 , the sealing piston  22  presses with its sealing ring  23  ever more tightly on the sealing surface  32  with increasing pressure. A servo action is obtained through this, i.e. a stronger pressure of the sealing ring  23  with increasing fluid pressure and thus a particularly reliable sealing of the quick connect coupling  10 . 
     In order to release the quick connect coupling  10  and thus restore the connected position shown in FIG. 2 to the open position, the actuating sleeve  50  is here retracted by hand through profiling on the outer surface. After this preferably pneumatic displacement (or by means of a lever) with retraction of the sliding sleeve  40  through a short stoke (corresponding to the length of the pressure chamber  27 ), the collet jaws  15  can spread radially inwardly again (or outwardly with external engagement with external collet jaw mounting), whereby the check valve  25  is simultaneously pushed here to the left towards the outlet end  13 , within the sliding sleeve  40 , under the action of the compression spring  19 . Before the sealing contact is thus released between the sealing piston  22  and the sealing surface  32 , the sealing surface  27 / 28  of the check valve  25  is closed, on account of the ability of the valve stem of the check valve  25  to move axially. Very rapid closure of the check valve  25  is achieved though this practically simultaneous sequence, so that no fluid volume can escape. 
     The conical form of the tip of the sliding sleeve  40  is also important in this, since the end facing the outlet  13  or the head piece  40 ′ assists the spreading out movement of the collet jaws  15 , so that the coupling of the quick connect coupling  10  is effected practically force-free and thus damage to the engagement profile  17  or the connection profile  31  is avoided. The sliding sleeve  40  also allows reliable fitting of the quick connect coupling  10  on to the connection nipple  30 , while the collet jaws  15  preferred as the locking element are only closed when the sealing contact between the sealing surface  32  or seal  33  in FIG.  4  and the sealing ring  23  is ensured, since the closing position of the check valve  25  is maintained long enough for the collet jaws  15  to be locked by the axial displacement of the sealing piston  22  and the freeing of the sliding sleeve  40  arising therefrom in direct sequence, in order thereby to produce very abrupt and especially reliable connection. The head piece  40 ′ of the sliding sleeve is preferably fixed interchangeably on the sliding sleeve  40  for adaptation to different collet jaw shapes or their inner surfaces  15 ′. 
     A further modified embodiment especially for gas cylinder valves is shown in FIGS. 3 and 4, wherein components acting in the same way are given the same reference numerals. A manual lever  50 ′ is here provided as an actuating device, which acts on an eccentric not described in more detail, as known from the initially recited state of the art.