Abstract:
The invention relates to a quick connect coupling ( 15 ) for connecting hydraulic lines, especially in earth moving machines and the interchangeable add-on devices and tools thereof. Said quick connect coupling ( 15 ) comprises a first and a second connecting part ( 15   a  or  15   b ) which can be releasably coupled along a coupling axis to transfer a hydraulic liquid. In order to avoid axial forces during coupling, the hydraulic liquid to be transferred, in the coupled state, emerges from the one connecting part ( 15   a  or  15   b ) at a right angle to the coupling axis and enters the other connecting part ( 15   b  or  15   a ) at a right angle to the coupling axis.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to the technical field of connecting hydraulic lines on earth moving machines, and to the tools and attachments thereof, as well as other hydraulic connections. It relates to a quick connect coupling according to the preamble to claim  1 . 
         [0003]    2. Description of Prior Art 
         [0004]    Known quick connect couplings for hydraulic connections generate in the connected state an axial force, which is formed by the piston area of the connecting nipple, multiplied by the hydraulic force. In small connections, locking mechanisms having a row of load-bearing balls are therefore often installed. 
         [0005]    In connections of larger aperture, large-sized threaded screw joints are essential. 
       SUMMARY OF THE INVENTION 
       [0006]    The object of the invention is therefore to provide a quick connect coupling which avoids the drawbacks of known quick connect couplings and is distinguished, in particular, by the fact that no axial force is generated in the connection of the hydraulics. 
         [0007]    The object is achieved by the totality of the features of claim  1 . The core of the invention consists in the quick connect coupling being configured such that, in the coupled state, the hydraulic fluid to be transferred emerges from one connecting part at a right angle to the coupling axis and enters the other connecting part at a right angle to the coupling axis. 
         [0008]    One embodiment of the invention is characterized in that in the coupled state a coaxial annular space for the transfer of the hydraulic fluid, which annular space is sealed to both sides in the axial direction, is configured between the two connecting parts, and in that the two connecting parts can exchange hydraulic fluid with the annular space through radial bores. 
         [0009]    A preferred refinement of this embodiment is distinguished by the fact that the two connecting parts comprise a female connecting part and a male connecting part, that the male connecting part has a first coaxial connecting piston with a first coaxial bore, that the female connecting part has a second coaxial connecting piston with a second coaxial bore for the reception of the first connecting piston, that the coaxial annular space is formed upon the insertion of the first connecting piston into the second coaxial bore of the second connecting piston, and that a first radial bore in the first connecting piston leads from the first coaxial bore into the coaxial annular space and a second radial bore in the second connecting piston leads from the coaxial annular space into the surrounding outer space of the second connecting piston. 
         [0010]    According to another embodiment of the invention, in the two connecting parts respectively an outer connection for the hydraulic fluid is arranged and a valve mechanism, which can preferably be actuated by the plug-in/unplugging operation, is provided, which valve mechanism interrupts the hydraulic connection between the respective connection and the first coaxial bore, and the surrounding outer space of the second connecting piston, when the connecting parts are parted and creates the hydraulic connection between the respective connection and the first coaxial bore, and the surrounding outer space of the second connecting piston, when the connecting parts are plugged together. 
         [0011]    In particular, the valve mechanism respectively comprises a sliding sleeve which is movable relative to the connecting piston in the axial direction, which sliding sleeve concentrically surrounds the connecting piston and has a through bore having a centrally located overflow space with enlarged internal diameter, the connecting piston dividing the through bore by means of a circumferential seal into two portions which are sealingly separated from each other and which communicate with each other only when, given a specific relative position of connecting piston and sliding sleeve, the circumferential sleeve is present in the overflow space. 
         [0012]    Another embodiment is distinguished by the fact that each connecting part has a housing, that the connecting pistons are respectively fixedly connected to the housing, and that the sliding sleeves are movable relative to the housing in the axial direction, the sliding sleeves, in particular, being retractable against the force of a compression spring counter to the plug-in direction. 
         [0013]    A further embodiment of the invention is characterized in that in the second coaxial bore of the second connecting piston a closing piston is arranged, which, when the connecting parts are parted, outwardly closes off the second coaxial bore and, when the connecting parts are plugged together, is retracted from the first connecting piston against the pressure of a compression spring into the second coaxial bore. 
         [0014]    Particularly with a view to a simplified assembly, it is advantageous if the connections are arranged at the rear ends of the connecting pistons, and if the connecting pistons, when the hydraulic line is connected, can be inserted into the housing from the rear and can be fastened to the housing. 
         [0015]    An alternative embodiment of the invention is characterized in that in the first connecting part a first space for the hydraulic fluid is provided, which first space extends in the direction of the coupling axis and communicates at one end with a connecting line of the first connecting part, in that in the second connecting part a second space for the hydraulic fluid is provided, which second space extends in the direction of the coupling axis and communicates at one end with a connecting line of the second connecting part, in that the first space can be closed at the other end by a first closing mechanism, which seals off the first space in the decoupled state and opens it in the coupled state, in that the second space can be closed at the other end by a second closing mechanism, which seals off the second space in the decoupled state and opens it in the coupled state, and in that both of the spaces and closing mechanisms are configured such that in the coupled state the hydraulic fluid flows between the two spaces substantially in the radial direction. 
         [0016]    Preferably, in the two closing mechanisms for closing the spaces, sealing points are configured, in which, owing to the pressure conditions, metal lies sealingly on metal. 
         [0017]    In particular, the two spaces are configured as annular spaces arranged concentrically to the coupling axis. 
         [0018]    A further embodiment of the invention is distinguished by the fact that the annular space in the first connecting part is configured between a central axial piston rod and an inner sliding sleeve concentrically surrounding the piston rod at a distance, and the associated closing mechanism is formed by the inner sliding sleeve and a connecting piston arranged at the front end of the piston rod, that the annular space in the second connecting part is configured between a sliding sleeve and an outer tube concentrically surrounding the sliding sleeve at a distance, and the associated closing mechanism is formed by the sliding sleeve and the outer tube, which is tapered at the front end, the inner sliding sleeve and the connecting piston in the first connecting part having the same external diameter and the tapered end of the outer tube and the sliding sleeve in the second connecting part having the same internal diameter, and that the external diameter is substantially equal to the internal diameter, so that, in the coupling process, the inner sliding sleeve and the connecting piston can travel into the tapered end of the outer tube and the sliding sleeve. 
         [0019]    In particular, the closing mechanism in the first connecting part is opened in the coupling process by the inner sliding sleeve being pushed rearward relative to the fixed connecting piston against the pressure of a spring, and the closing mechanism in the second connecting part is opened in the coupling process by the sliding sleeve being pushed rearward relative to the fixed, tapered end of the outer tube against the pressure of a spring. 
         [0020]    Another embodiment is distinguished by the fact that, for the displacement of the sliding sleeve in the first connecting part, an outer sliding sleeve is provided, which concentrically encloses the inner sliding sleeve, is displaceable in the axial direction and can be actuated by the outer tube of the second connecting part, and that, for the displacement of the sliding sleeve in the second connecting part, a closing piston is provided, which is concentrically enclosed by the sliding sleeve, is displaceable in the axial direction and can be actuated by the connecting piston of the first connecting part, in the first connecting part between the outer sliding sleeve and the connecting piston, and in the second connecting part between the closing piston and the tapered end of the outer tube and the sliding sleeve, seals being arranged, and the closing mechanisms only opening when the seals are fully covered. 
         [0021]    In addition, in the closing piston means can be installed to obtain the effect of a check valve, which means in particular comprise a thin valve disk, which from inside, in an oil-tight manner, closes off valve bores made in the closing piston. 
         [0022]    Furthermore, it is advantageous for the working if small relief grooves are recessed on the connecting piston and on the closing piston and small grooves are recessed in the closing piston on the end face. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0023]    The invention shall be explained in greater detail below in connection with the drawing, wherein: 
           [0024]      FIG. 1  shows the arm, equipped with an extension, of an earth moving machine, for example of an excavator with quick connect couplings arranged at the junction point, according to one illustrative embodiment of the invention; 
           [0025]      FIG. 2  shows in an exploded representation the male connecting part of a quick connect coupling according to  FIG. 1 ; 
           [0026]      FIG. 3  shows in an exploded representation the female connecting part of a quick connect coupling according to  FIG. 1 ; 
           [0027]      FIG. 4  shows the two connecting parts from  FIGS. 2 and 3  in the assembled state prior to coupling; 
           [0028]      FIG. 5  shows the two connecting parts from  FIG. 4  in the coupled state; 
           [0029]      FIG. 6  shows the top view, in axial direction, of the fastening means for fastening the connecting piston to the housing covers of the two connecting parts from  FIGS. 2 and 3 ; 
           [0030]      FIG. 7  shows two connecting parts according to another illustrative embodiment of the invention in the assembled state prior to coupling; 
           [0031]      FIG. 8  shows the two connecting parts from  FIG. 7  in the coupled state; 
           [0032]      FIG. 9  shows the rapid connection system comprising a plurality of quick connect couplings according to  FIGS. 4 and 5 , which are combined in a block; and 
           [0033]      FIGS. 10   a - e  show in various sub-figures a quick-connect coupling according to another illustrative embodiment of the invention, various phases in the coupling process being portrayed in the sub-figures and sub- figure 10   c  showing an enlarged detail from sub- figure 10   b.    
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0034]    Quick connect couplings according to the invention can be used in a wide variety of sectors where hydraulic lines must be releasably connected to one another in a fast and uncomplicated manner. A particularly important field of application is that of earth moving machines (for example excavators or the like) and the tools and attachments thereof. In  FIG. 1 , as one application example, an arm  10  of an excavator. (not represented) is shown, to whose one end an extension  11  is added. Coming from the excavator, first hydraulic lines  14  run along the arm  10  and are intended to be connected at the junction point  12  to second hydraulic lines  13 , which lead along the extension  11  to a tool or the like. For the releasable connection of the first and second hydraulic lines  14  and  13 , a number of quick connect couplings  15  corresponding to the number of hydraulic lines  13 ,  14  are arranged in the region of the junction point  12 , which are realized according to a preferred illustrative embodiment of the invention (the connection of the hydraulic lines  13 ,  14  to the quick connect couplings  15  is only hinted at in  FIG. 1 ; the lines are not traced). 
         [0035]    One of the hydraulic couplings  15  from  FIG. 1  is represented in  FIG. 4  in the unplugged state and in  FIG. 5  in the plugged together state. The hydraulic line  15  comprises two connecting parts  15   a  and  15   b , which can be releasably plugged together to create the hydraulic connection. The connecting part  15   a  is configured as a female connecting part, the connecting part  15   b  as a male connecting part. The internal structure of the two connecting parts  15   a  and  15   b  of the quick connect coupling  15  is portrayed in  FIG. 3  and  FIG. 2 , respectively, in exploded representation. The male connecting part  15   b  of  FIG. 2  comprises a hollow cylindrical housing  16 , which is closed off on the end face (viewed in the plugging direction) by an end wall  17 . In the end wall  17 , a concentric opening  18  is provided, through which, in the assembled state, the front part  20  of a sliding sleeve  19  reaches, which sliding sleeve is mounted in the housing  16  such that it is displaceable in the axial direction (axis A) (see right-hand side of  FIG. 4 ). 
         [0036]    The sliding sleeve  19  has a middle part  21  of enlarged external diameter and rests with this middle part  21  against the inside of the end wall  17 . The housing  16  is closed on the rear side by a housing cover  25 , which has spaced apart threaded holes  26   a ,  26   b  for the fitting of fastening means  41 . In the housing cover  25  a concentric opening  27  is provided, through which the sliding sleeve  19  can be inserted axially into the housing  16  from the rear. The sliding sleeve  19  has a central, coaxial through bore  22 , which serves for the (seal-forming) reception of a connecting piston  29 . The through bore  22  of the sliding sleeve  19  has in the middle part  21  a portion of widened internal diameter, which portion, in connection with the below-described valve function of the sliding sleeve  19 , serves as an overflow space  23 . 
         [0037]    The cylindrical connecting piston  29  is fixedly mounted in the housing  16 . For this, it is equipped at the rear end (on the right in  FIG. 2 ) with a piston foot  38  of widened diameter, which has a coaxial annular groove  39 . When the connecting piston  29  is inserted by its front end in the through bore  22  of the sliding sleeve  19  and is introduced together with the sliding sleeve  19  through the opening  27  in the housing cover  25  from the rear into the housing  16 , the outer side of the housing cover  25  terminates flush with the front side wall of the annular groove  39  in the piston foot  38 . Semicircular clamps  42 ,  43  can then be inserted from opposite sides into the annular groove  39  and screwed to the housing cover  25  by means of fastening screws  46 ,  47  ( FIG. 4 , right-hand side). The connecting piston  29  is thus firmly connected to the housing cover  25  and thus also to the housing  16 . Between the sliding sleeve  19 , concentrically surrounding the connecting piston  29 , and the piston foot  38  a compression spring  24  is arranged, which rests against the piston foot  38  and presses and pressurizes the sliding sleeve  19  with its middle part  21  against the end wall  17 . 
         [0038]    The connecting piston  29  has two concentric blind bores  32  and  37  reaching from opposite sides into the piston. The front (in  FIG. 2 , left-hand) blind bore  32  is closed by a stopper  28 . A connection of the front blind bore  32  to the outer space is created by one or more radial bores  30 , which is/are arranged between two axially spaced-apart concentric seals  36  on the outer side of the connecting piston  29 . As a result of the two seals  36 , a coaxial annular space ( 82  in  FIG. 5 ) communicating with the front blind bore  32  is formed when the connecting piston  29  is inserted into a corresponding bore. 
         [0039]    In the intermediate portion between the two blind bores  32  and  37 , a circumferential seal  34  is arranged on the outer side of the connecting piston  29 . On both sides of the seal  34 , the connecting piston  29 , in one portion, is tapered in terms of its external diameter. In the tapered portions, connecting bores  33   a, b  and  35   a, b  open out into the outer space, which connecting bores connect the blind bores  32  and  37  to the outer space in front of and behind the seal  34 . The rear blind bore  37  passes at the rear end (in the piston foot  38 ) into a connection with connecting thread  40  for the connection of a hydraulic line. 
         [0040]    The female connecting part  15   a  shown in  FIG. 3  in exploded representation and in  FIG. 4 , on the left-hand side, in the assembled state has a structure which is essentially in mirror image to  FIG. 2 . Here too, a hollow cylindrical housing  48  having an end wall  49  with concentric opening  50  is present, which housing receives an axially displaceable, second sliding sleeve  55 . The sliding sleeve  55  has a central, coaxial through bore  58  for receiving a second connecting piston  64 . The second connecting piston  64  likewise has a piston foot  72  with annular groove  73 , and is screwed by means of comparable fastening means  75 , comprising two clamps  76 ,  77  and fastening screws  80 ,  81 , to a corresponding housing cover  61 , which is equipped with threaded holes  62   a, b  for the fastening screws  80 ,  81  and a concentric opening  63  through which the second sliding sleeve  55  and the piston foot  72  can be pushed. 
         [0041]    The second sliding sleeve  55  projects with a front part  56  through the opening  50  in the end wall  49  and rests with a thickened middle part  57  against the inner side of the end wall. Between the middle part  57  and the piston foot  72  of the second connecting piston  64  is arranged a compression spring  60  ( FIG. 4 , left-hand side), which rests against the middle part  57  and the piston foot  72  and presses and pressurizes the sliding sleeve  55  against the end wall  49 . 
         [0042]    The second sliding sleeve  55 , too, has a coaxial through bore  58 , which in a middle portion widens in terms of its internal diameter to form an overflow space  59 . The second connecting piston  64 , too, has two coaxial blind bores  68  and  71  reaching from opposite sides into the piston. In the intermediate portion between the two blind bores  68  and  71 , a circumferential seal  69  is arranged on the outer side of the second connecting piston  64 . On both sides of the seal  69 , the connecting piston  64 , in one portion, is tapered in terms of its external diameter. In one tapered portion to the left of the seal  69 , connecting bores  70   a, b  open out into the outer space, which connecting bores connect the left-hand (rear) blind bore  71  to the outer space behind the seal  69 . The other blind bore  68  has a coupling space  67  of slightly enlarged internal diameter, in which radial bores  66  lead outward and connect the front blind bore  68  to the outer space. At the front end of the second connecting piston  64 , the tapered portion situated to the right of the seal  69  is terminated by a seal-forming ring arrangement  65 . The rear blind bore  71  passes at the rear end (in the piston foot  72 ) into a connection with connecting thread  74  for the connection of a hydraulic line. In the front blind bore  68  is seated, axially displaceably, a closing piston  51 , which is pressurized in the outward direction by a further compression spring  54 . For the reception of the compression spring  54 , a blind hole  52  is sunk into the closing piston  51  from the rear, which, by virtue of a small safety bore  53 , communicates in the forward direction with the outer space. 
         [0043]    In the non-assembled state ( FIG. 4 ), the axial position of the seals  34  and  69  arranged on the connecting pistons  29  and  64  relative to the overflow spaces  23  and  59  in the sliding sleeves  19  and  55  is such that the seals  34 ,  69  are located outside the overflow spaces  23 ,  59  in the through bore  22  and  58 , respectively, and hydraulically separate the spaces in front of and behind the seals  34 ,  69  one from the other. Accordingly, no hydraulic connection exists between the rear blind bores  37 ,  71  and the front blind bore  32  (in the case of the connecting piston  29 ) and the space between the seal  69  and the ring arrangement  65  (in the case of the connecting piston  64 ). 
         [0044]    When the two connecting parts  15   a  and  15   b , preassembled according to  FIG. 4 , are plugged together (the end state is shown in  FIG. 5 ), the two sliding sleeves  19  and  55  are pushed, against the pressure of the corresponding compression springs  24  or  60 , in the axial direction rearward into the housing  16  or  48  until the end faces of the sliding sleeves  19 ,  55  terminate flush with the outer sides of the end walls  17  and  49 , respectively. In this end setting ( FIG. 5 ), the overflow spaces  23  and  59  are located directly above the seals  34  and  69 , respectively, so that a hydraulic connection between the tapered portions is created on both sides of the seals  34 ,  69 . 
         [0045]    At the same time, the closing piston  51  in the left-hand connecting piston  64  is forced back into the left-hand connecting piston  64 , against the pressure of the compression spring  54 , by the right-hand connecting piston  29  and frees the coupling space  67  with the radial bores  66  present therein. The right-hand connecting piston  29  travels into the blind bore  68  of the left-hand connecting piston  64  to the point where the radial bores  30  and  66  are standing directly one above the other and the seals  36  laterally delimit the coupling space  67  and form a coaxial annular space  82 , via which the two connecting parts  15   a, b  with their connecting pistons  29 ,  64 , in the radial direction and without axial pressure forces, can exchange hydraulic fluid, which hydraulic fluids are supplied and removed, respectively, via the connections  40 ,  74  and the blind bores  37  and  71  connecting thereto. 
         [0046]    Alternatively to the illustrative embodiment from  FIGS. 2-5 , a closing piston  51  can also, however, be dispensed with. A simplified configuration of this kind is portrayed, by way of example, in  FIGS. 7 and 8 , which correspond to  FIGS. 4 and 5 . In this quick connect coupling  15 ′, too, connecting parts  15   a ′ (female) and  15   b ′ (male) are present, which respectively have in housings  16 ′ and  48 ′ connecting pistons  29 ′ and  64 ′ of the already described type, surrounded by sliding sleeves  19 ′ and  55 ′, inclusive of the radial bores  30  and  66 . The right-hand connecting piston  29 ′ here once again travels into the left-hand connecting piston  64 ′, without, however, having to displace a closing piston. As a result of the longer overlap of the two connecting pistons, a better sealing is in this case obtained. 
         [0047]    If at the site of use a plurality of quick connect couplings need to be used, like the three quick connect couplings  15  shown in  FIG. 1 , it is expedient according to  FIG. 9  to provide a rapid connection system  83  in block construction, in which connecting parts  15   a  and  15   b  which are preassembled on the hose can be individually installed in a block  85  and  84 , respectively. This makes assembly very much easier in cramped spatial conditions. The blocks  84 ,  85  are equipped with locating and centering pins. Likewise, the blocks  84 ,  85  are elastically supported by springs, so that they can adjust to each other. 
         [0048]    The quick connect coupling according to  FIGS. 2-5  additionally has the following safety features. In the closing piston  51 , a small safety bore  53  is provided (on the right) on the end face. In the male connecting piston  29 , a further small safety bore  31  is present (on the left) on the end face, which opens out outward into a transverse bore. In the connected state, these bores  31 ,  53  act as safety relief bores:
       Should the foremost sealing ring in the connecting piston  29  exhibit a minor leak, the undesirable, large axial force would build up and force the blocks  84 ,  85  apart.   Behind the closing piston  51 , in the event of a minor leak at the rear sealing ring (on the left) in the decoupled state, a quantity of oil could accumulate, which can in this case escape through the safety bore  53 . In the connection process, this closing piston  51  is pressed in by the connecting piston  29 , whereby the space behind the closing piston  51  is diminished. A large oil volume in this space could now escape through the above-described safety relief bore.   As a result of the play which the connecting piston  29  has in the sliding sleeve  19 , a drainage of the displaced oil in the outward direction is possible.   It should be borne in mind that we are here discussing a theoretical leak involving a small quantity of oil.       
 
         [0053]    A further, particularly advantageous illustrative embodiment of a quick connect coupling according to the invention is portrayed in  FIGS. 10   a - e  in various progressive phases of the coupling operation,  FIG. 10   c  portraying an enlarged detail from  FIG. 10   b . The quick connect coupling  100  of  FIGS. 10   a - e  comprises two connecting parts, namely a male connecting part  100   a  and a matching female connecting part  100   b.    
         [0054]    The male connecting part  100   a  is based on a coupling element having a piston rod  136  which extends in the direction of coupling and at the front end of which is arranged a connecting piston  110  ( FIG. 10   c ). The piston rod  136  is concentrically surrounded on the outside, at a distance, by a tube  103 , which is screwed to the coupling element  100   a . Within the tube  103 , a seal carrier ring  104  is concentrically housed, in which an inner sliding sleeve  106  is mounted such that it can be displaced axially rearward against the force of a spring  105  and is outwardly sealed off by a seal  112  housed in the seal carrier ring  104 . In the uncoupled state, the inner sliding sleeve  106  butts with a front sealing edge  118  ( FIG. 10   c ) against the rear side of the connecting piston  110  and forms there a sealing point at which metal meets metal. 
         [0055]    Between the tube  103  and the inner sliding sleeve  106 , an outer sliding sleeve  108  is concentrically mounted such that it is axially displaceable, against the pressure of a spring  111 , relative to the tube  103 , the inner sliding sleeve  106  and the connecting piston  110 , and is inwardly sealed against the inner sliding sleeve  106  and the connecting piston  110  by means of the seals  113  and  114 . The spring  111  is arranged laterally on the outside and is acted upon by means of a guide plate  109  which is fixedly attached to the front end of the outer sliding sleeve  108  and concentrically surrounds the outer sliding sleeve  108 . Between the piston rod  136  and the inner sliding sleeve  106 , a coaxial annular space  137  is configured, which on the male side communicates via connecting bores  138  with the connecting line  101  ( FIG. 10   b ). The male connecting part  100   a  is, with the tube  103 , screwed tightly into a carrier plate  107  lying at a right angle to the direction of coupling. 
         [0056]    The female connecting part  100   b  is based on a coupling element which supports a sliding sleeve  127  mounted such that it is axially displaceable against the pressure of a spring  128 . The sliding sleeve  127  is concentrically surrounded on the outside, at a distance, by a tube  129 , which is screwed by the rear end onto the coupling element  100   b  and is screwed by the front end into a carrier plate  122 . The tube  129  narrows at the front end. In the uncoupled state, the sliding sleeve  127  butts with a sealing edge  119  ( FIG. 10   c ) against the rear side of the narrowing of the tube  129  and there likewise forms a sealing point at which metal meets metal. In the sliding sleeve  127  and the narrowed front part of the tube  129 , a closing piston  123  is mounted such that it is axially displaceable against the pressure of a spring  124 , and is held in such a way on the coupling element  100   b  by means of a spacer bushing  126  and a retaining screw  125  that in the uncoupled state it terminates on the front side flush with the front end of the tube  129 . The closing piston  123  is outwardly sealed off by seals  115  and  116  against the narrowed portion of the tube  129  and the sliding sleeve  127 , respectively. Between the sliding sleeve  127  and the tube  129 , a coaxial inner space  139  is configured, which on the female side communicates via connecting bores  140  with the connecting line  131  ( FIG. 10   b ). 
         [0057]    In this illustrative embodiment also, the essential feature is that, when the coupled connection is acted upon by hydraulic pressure, no axial force is generated. This is realized by virtue of the fact that, in the male quick connect coupling part or connecting part  100   a , a connecting piston  110  is fastened to a piston rod  136 , which, when coupling is made with the female quick connect coupling part or connecting part  100   b , projects into the same. 
         [0058]    The female quick connect coupling part  100   b  is constructed such that, in the coupling process, a closing piston  123  is pushed by the end face of the connecting piston  110  of the male quick connect coupling part  100   a  into a pressure-free space. In this arrangement, the force which is formed by the ring surface of the connecting piston  110 , multiplied by the hydraulic force, is fully absorbed by the abovementioned piston rod  136 . In order reliably to prevent a possible build-up of the aforementioned force which could seriously damage the holding plates or carrier plates  107 ,  122 , as well as the associated fastenings to the machine parts, a leakage oil line  121  is provided, which is connected to a leakage oil bore  120  and which can drain off a possible minor leak at the seals  116 ,  117  and leads back into the tank. 
         [0059]    At the same time, the pumping action of the closing piston  123  is used to suck off any leak oil in the decoupling process. For this purpose, means for attaining the effect of a check valve are installed in the closing piston  123 . In a preferred embodiment of these means, a thin valve disk  132  is provided. This closes from the inside four valve bores  133  made in the closing piston  123  and allows no oil to escape. If, prior to the coupling, oil is present behind this valve disk  132 , this oil is forced into the tank through the check valve in the nipple of the leak oil line  121 . 
         [0060]    When the system is decoupled, a vacuum is formed in the space behind the closing piston  123 , whereby the valve disk  132  is forced inward by the static ambient pressure. At the same time, a small quantity of oil which collects on the end faces of the connecting piston  110  and closing piston  123  as a result of having passed over the sealing rings during decoupling can be sucked off through the valve bores  133 . 
         [0061]    In the connected state ( FIG. 10   e ), for the large oil stream, a flow-favorable transfer from the male into the female quick connect coupling part  100   a  or  100   b , or vice versa, is obtained. The flow transfer runs substantially radially, the sliding sleeves  106  and  127  and the connecting piston  110  with piston rod  136  being coaxially flowed around, or flowed through, by the oil. Circumferential seals  112 , . . . ,  117  with specific, small diameter differences produce at the displaceable sleeves  106 ,  127  purposefully small axial forces, which assist the springs  105 ,  128  in the closing operation. At the same time, they prevent the oil from possibly making its way outward or along the connecting piston  110 , on the end face thereof. 
         [0062]    In the decoupled, closed state ( FIG. 10   a ), the closing forces with which the inner sliding sleeve  106  acts upon the connecting piston  110  and the sliding sleeve  127  acts against the tube  129  on the female side are additionally reinforced by a possible hydraulic residual pressure. This is realized by virtue of the fact that machined metallic sealing edges  118 ,  119  ( FIG. 10   c ) differ in diameter from the seals  112 ,  117  in such a way that small ring surfaces are obtained. In this way, both coupling parts are already relatively tightly closed. The coupling parts  100   a ,  100   b  are definitively tightly sealed by the seals  112 , . . . ,  117 . 
         [0063]    In order to prevent the seals  114 ,  115 ,  116  from being damaged under hydraulic pressure in the coupling operation, small relief grooves  134  ( FIG. 10   c ) are recessed on the connecting piston  110  and on the closing piston  123 . A small quantity of oil can be evacuated through these relief grooves  134  in order to relieve the hydraulic tension between the seals  113  and  114  and  115  and  116  before the seals  114 ,  115 ,  116  pass over the dividing points between the connecting piston  110  and the inner sliding sleeve  106  on the one hand, and the connecting piston  110  and the closing piston  123  on the other hand. The small quantity of oil which has hereupon escaped collects on the end faces of the connecting piston  110  and closing piston  123 , in which, on the end face, small grooves  135  are recessed, which lead to the valve bores  133 . This quantity of oil is sucked off in the decoupling process by the already described vacuum. 
         [0064]    As a result of this construction, it is possible to couple pressurized lines without the need for large forces. 
         [0065]    Pressurized quick connect couplings according to the present invention generate no axial forces which force apart the two coupling parts. Accordingly, no large force has to be surmounted in the coupling process. Merely the forces of all springs force the parts apart, and an increased friction of the seals under hydraulic load has to be surmounted. In addition, the above-described small forces generated by the ring surfaces, multiplied by the hydraulic pressure, have to be surmounted. 
         [0066]    In the coupling operation according to  FIGS. 10   a - e , the two quick connect coupling parts  100   a ,  100   b  move in a first step ( FIGS. 10   b  and  10   c ) one against the other, so that the male connecting part  100   a  hits with the connecting piston  110  the pressure piston  123  in the female connecting part  100   b.    
         [0067]    In  FIG. 10   d , the male connecting part  100   a , with the connecting piston  110 , pushes the closing piston  123  into the sliding sleeve  127  as far as the stop. In this position, the parts are tightly connected. The oil flow is not yet released by the metallic sealing edges  118 ,  119 . In the male coupling part  100   a , the inner sliding sleeve  106  is forced by the spring  105  for the inner sliding sleeve against the inner side of the piston  110  on the male connecting part  100   a . And in the female quick connect coupling part  100   b , the sliding sleeve  127  which is present there is forced by the spring  128  for the sliding sleeve against the correspondingly shaped inner side of the tube  129  of the female side. By virtue of the relief grooves  134 , the seals  114 ,  115 ,  116  have here been passed over without being subjected to load by hydraulic pressure. When connection is made under pressure, passage is only freed once all the seals are fully covered. On the other hand, an existing oil stream is stopped by the metallic sealing edges  118 ,  119 , and the seals  114 ,  115 ,  116  are only passed over once these can no longer be damaged by an oil stream which can suddenly be stopped. 
         [0068]    In  FIG. 10   e , a fully brought-together quick connect coupling  100  is represented. Both sliding sleeves  106 ,  127  are here fully inserted and free the entire cross section. 
         [0069]    All in all, the quick connect coupling according to the invention has the following features:
       Rapid connection system for high-pressure hydraulics couplable under pressure.   Rapid connection system without outward-acting axial forces upon pressurization. This is realized by virtue of the lateral arrangement of the oil intake and discharge bores.   Circumferential seals prevent the oil from possibly making its way along the end face thereof. In the decoupled state, sliding sleeves present the escape of oil.   As a result of this construction, it is possible to couple and decouple pressurized lines, without the need for large forces.   Quick connect coupling with continuously large cross sections, in accordance with the nominal size, in order to prevent braking effects and heat development.   Quick connect coupling which is fluidically advantageously designed, inter alia because there are no springs present in the flowed-through spaces.   Quick connect coupling having design measures which prevent the seals from being damaged under pressure by the oil stream in the course of coupling or decoupling. This is realized by virtue of the fact that any oil stream is retained under pressure by metallic closures. The seals are passed over by the closing and connecting parts only with minimal pressure.   Quick connect coupling especially suited for use in sheet blanks for multiple couplings.   Quick connect coupling for automatic coupling operation.   Quick connect coupling having closing parts which, following decoupling, prevent residual oil quantities from running out.   Quick connect coupling particularly suitable for combined multiple use in carrier plates.