Abstract:
A quick-release coupling for fluid lines is disclosed which includes a connector with a connecting piece and at least one connecting pipe transversely projecting from the connecting piece, which connecting piece can be inserted into a receiving opening of a counterpart in a sealing manner and brought into locking engagement with the counterpart. To improve reliability and ease of mounting of a quick-release coupling, a force used to convert a securing device from an unlocking position to a locking position can be larger than a force used to bring the connecting piece into locking engagement with the counterpart.

Description:
[0001]    The invention relates to a quick-release coupling for fluid lines, comprising: a connector with a connecting piece and at least one connecting pipe transversely projecting from said connecting piece, the connecting piece being of the type that can be inserted into a receiving opening of a counterpart in a sealing manner and brought into locking engagement with said counterpart by means of a locking or latching means; and a securing means that can be converted from a locking position in which the locking engagement is secured against unlocking to an unlocking position in which the locking engagement can be disengaged or released. 
         [0002]    Such a quick-release coupling is known from WO 2007/042344 A1. When mounting said quick-release coupling, the connecting piece, on the one hand, has to be brought into locking engagement with said counterpart while, on the other hand, the securing means has to be converted from the unlocking position to the locking position. Occasionally, the connecting piece is not in full locking engagement with the counterpart, or the locking engagement releases unintentionally before the securing means is converted from the unlocking position to the locking position. Improper mounting of the quick-release couplings which are used, for instance, in vehicle leakage oil pipes implies considerable danger that the quick-release couplings might get disengaged under operation and, thus, fail to meet the coupling and sealing functions in a sufficient manner. 
         [0003]    The invention is based on the object to improve reliability and ease of mounting of a quick-release coupling as mentioned above. 
         [0004]    To solve the object basing the invention, a quick-release coupling for fluid pipes is provided, comprising: a connector with a connecting piece and at least one connecting pipe transversely projecting from said connecting piece, the connecting piece being of the type that can be inserted into a receiving opening of a counterpart in a sealing manner and brought into locking engagement with said counterpart by means of a locking means; and a securing means that can be converted from a locking position in which the locking engagement is secured against unlocking to an unlocking position in which the locking engagement can be disengaged, wherein a force used to convert the securing means from the unlocking position to the locking position (latching force) is larger than a force used to bring the connecting piece into locking engagement with the counterpart (insertion force). It may turn out to be useful to have the securing means being converted between locking position and unlocking position by being moved along the axis of the connecting piece. Preferably, the latching force and the insertion force are applied to the securing means in the insertion direction of the connecting piece, in order to optimally couple the latching movement of the securing means to the insertion movement of the connecting piece. As the latching force is larger than the insertion force, the connecting piece inevitably snaps into the counterpart while the securing means is being latched. Hence follows that the connecting piece and the counterpart inevitably are in locking engagement when the securing means is in the locking position. Accordingly, by locking or fixing the locking position of the securing means the locking engagement of the connecting piece with the counterpart can simultaneously be verified, thereby enhancing the process reliability while mounting the quick-release coupling and reducing the production costs, because the locking engagement does not have to be checked separately. According to the inventive solution, unintentional mounting errors can a priori be avoided owing to structural measures for error proofing (poka-yoke principle). Preferably, the connector substantially is X-, T-, Y- or L-shaped and preferably comprises two connecting pipes, the axes thereof lying in the same plane or in different planes with the axis of the connecting piece. The securing means preferably can be fixed to the connector in the locking position and/or unlocking position in a non-positive or force-fit and/or positive or form-fit, preferably in a latching manner. Optionally, an optically, haptically and/or acoustically sensible signal is generated when the securing means is being locked and/or unlocked. Preferably, the securing means embraces or encloses the connector in the locking position and/or in the unlocking position at least partially. 
         [0005]    Any advantageous developments of the invention are subject-matters of the sub-claims. 
         [0006]    It may turn out to be advantageous to have the securing means arranged, at least section-wise, on a side facing away from the connector in counter-insertion direction of the connecting piece. Thus, the securing means still can be easily mounted to the connector even when the connector has already been inserted. 
         [0007]    It may be helpful to have the securing means being provided with an actuating element which is arranged on a side facing away from the connector in counter-insertion direction of the connecting piece. The securing means can, thus, be actuated or operated more easily. 
         [0008]    It may turn out to be useful to have the actuating element being designed in a substantially annular shape. The term “annular” means that the actuating element or a section thereof extends along a self-contained line and is preferably formed in an annular, polygonal or other shape. The actuating element may, e.g. also be of mirror-symmetric of rotation-symmetric form and arranged concentrically to the axis of the connecting piece. Thus, forces acting on the actuating element can be evenly distributed so as to avoid that any moments of tilt or of torsion arise that might result in wedging the securing means with regard to the connector. 
         [0009]    It may also be beneficial to have the actuating element being provided with at least one actuating surface facing away from the actuating element in counter-insertion direction of the connecting piece and/or at least one actuating surface facing away from the actuating element in the direction of insertion of the connecting piece. Owing to such measure, compressive forces can act on the operating surface(s) exactly in or against the direction of insertion of the connecting piece so as to avoid any moments of tilt or of torsion that might result in wedging the securing means with regard to the connector. 
         [0010]    According to an advantageous development of the invention, the actuating element comprises an opening extending—preferably in counter-insertion direction of the connecting piece—in or through said actuating element. Such opening may, e.g. be used either as display means or for visual inspection in order to find out the position of the securing means with regard to the connector. 
         [0011]    It may turn out to be advantageous to have at least a part of the connector being receivable in the actuating element opening. The actuating element can, thus, be positioned with particular accuracy with regard to the connector. 
         [0012]    It may be useful to have at least a part of the connector, preferably said part of the connector that has been received in the opening, lining up precisely with at least one part of the actuating element in at least one position of the securing means, preferably in the locking position. Thus, it is particularly easy to find out the position of the securing means with regard to the connector by means of visual or haptic examination. 
         [0013]    In another advantageous development of the invention, the securing means has an inner contour matching to the outer contour of a part of the connector so that the securing means is movably guided with regard to the connector between the unlocking and the locking position, preferably in a torsion-proof and/or tilt-proof manner. Incorrect handling of the securing means can, thus, largely be avoided. 
         [0014]    It may be proven beneficial to have the securing means and/or the connector being provided with at least one snap-in protrusion, at least one guiding web and at least one snap-in reception arranged in said guiding web, the snap-in protrusion being conducted in a gliding manner between the locking position and the unlocking position in said guiding web, and the snap-in protrusion being catchable in said snap-in reception in the locking position and/or unlocking position. Thus, the securing means is positioned in the locking position and in the unlocking position but also in each intermediate position exactly with regard to the connector, the hazard of incorrect handling or operation thereby substantially being excluded. 
         [0015]    It may be advantageous to have the securing means being provided with an actuating element secured to the connector by means of a securing element which is secured to the connector preferably in a detachable manner. According to one embodiment, the securing element is a lid or cover which can be connected to the connector by means of plug-in connection. According to another embodiment, the securing element or a portion thereof can be inserted into an opening of the connector, preferably into an opening of a fastening means. According to yet another embodiment, the securing element or a portion thereof can be attached to the connector, preferably to a fastening means and/or to at least one of said connecting pipes. To this end, the securing element may comprise one, two or more attachment portions. According to still another embodiment, the actuating element can be fixed to the securing element in at least one position, preferably in the unlocking position and/or in the locking position. According to still another embodiment, the securing element overlaps the actuating element on the rim-side and/or holds same to the connector in a captive manner. Further, it may be advantageous to have the securing element being of a longer form than the width of the actuating element. 
         [0016]    A further aspect of the invention relates to a quick-release coupling for fluid pipes, comprising: a connector with a connecting piece and at least one connecting pipe transversely projecting from said connecting piece, the connecting piece being of the type that can be inserted into a receiving opening of a counterpart in a sealing manner and brought into locking engagement with said counterpart by means of a locking means; and a securing means that can be converted from a locking position in which the locking engagement is secured against unlocking to an unlocking position in which the locking engagement can be disengaged, wherein the locking means comprises at least one locking or latching arm, wherein the securing means and the locking arm have contours matching to each other so as to allow the securing means to be guided at said locking arm in a gliding manner between the unlocking position and the locking position in a torsion-proof or tilt-proof manner. Preferably, the inner contour of the securing means matches the outer contour of the locking arm, or vice versa. To this end, the securing means and the locking arm cooperate like female and male guide means. According to an embodiment, the contours of the securing means and of the locking arm match to each other in such a manner that the securing means can only be moved along an axis preferably extending parallel to the direction of insertion and/or parallel to the axis of the connector, while all other degrees of freedom of the securing means, particularly a movement transverse to said axis and/or a rotation about any axis, are blocked. 
         [0017]    It may be useful to have the securing means being provided with at least two guide sections flanking a locking arm of the locking means on both sides and being guided at said locking arm in a gliding manner during the conversion between locking position and unlocking position. Thus, the securing means can be stabilized at the connecting piece or at the locking arm of the locking means in a tilt-free manner. This is particularly useful when large forces for converting the securing means from the unlocking position to the locking position have to be applied to the securing means. It can thus be ensured that the actuating surfaces of the securing means have been oriented optimally to receive the actuating forces and that the actuating forces exclusively act in/or against the direction of insertion of the connecting piece. According to one embodiment, the guide portions constitute a guide channel which receives the locking arm in a gliding manner during the conversion between the locking position and the unlocking position. During the conversion between the locking position and the unlocking position, the locking arm preferably moves deeper into the guide channel. According to another embodiment, a securing portion is provided between said two guide portions. In this concept, the two guide portions serve as stabilizing elements and are provided laterally adjacent to the securing portion, in order to position the securing portion firmly between the connecting piece and the locking arm and, thus, to block the locking arm. Said design has particularly been developed for automated connector mounting. According to yet another embodiment, the securing means comprises two guide portions for each locking arm of the locking means, said guide portions flanking said locking arm on both sides thereof and being guided to said locking arm in a gliding manner during the conversion between the locking position and the unlocking position. 
         [0018]    The described embodiments can be combined arbitrarily. Preferred further developments of the invention can be obtained by combining the features disclosed in the claims, in the description and in the drawings. 
     
    
     
       SHORT DESCRIPTION OF THE FIGURES 
         [0019]      FIG. 1  is a perspective, partial section view of the quick-release coupling according to a first embodiment of the invention with a matching counterpart, with the securing means being in the unlocking position. 
           [0020]      FIG. 2  is a perspective view of the quick-release coupling according to the first embodiment of the invention, with the securing means being in the locking position. 
           [0021]      FIG. 3  is a plan view of the quick-release coupling according to the first embodiment of the invention in the unlocking position and in the locking position, wherein  FIG. 3   a  shows a section along line A-A and  FIG. 3   b  shows a section along line B-B. 
           [0022]      FIG. 4  is a perspective view of the quick-release coupling according to the first embodiment of the invention in locking engagement with the matching counterpart, with the securing means being in the unlocking position. 
           [0023]      FIG. 5  is a perspective view of the quick-release coupling according to the first embodiment of the invention in locking engagement with the matching counterpart, with the securing means being in the locking position. 
           [0024]      FIG. 6  is a perspective view of the quick-release coupling according to a second embodiment of the invention, with the securing means being in the unlocking position. 
           [0025]      FIG. 7  is a side view of the quick-release coupling according to  FIG. 6 . 
           [0026]      FIG. 8  is another side view of the quick-release coupling according to  FIG. 6 . 
           [0027]      FIG. 9  is a plan view of the quick-release coupling according to  FIG. 6 , wherein  FIG. 9   a  shows a section along line A-A and  FIG. 9   b  shows a section along line B-B. 
           [0028]      FIG. 10  is a perspective exploded view of the quick-release coupling according to a third embodiment of the invention. 
           [0029]      FIG. 11  is a perspective view of the quick-release coupling according to the third embodiment of the invention in a mounted condition. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0030]    The first embodiment of the invention which will be described below with regard to  FIGS. 1 to 5  relates to a quick-release coupling  1  for fluid pipes in the form of a leak-oil connector.  FIG. 1  is a perspective view of the inventive quick-release coupling  1  according to the first embodiment with a counterpart  6  with a matching receiving opening  5 , with the securing means  8  being in the unlocking position. 
         [0031]    The inventive quick-release coupling  1  comprises an integrally formed, substantially T-shaped connector  2  of a glass-fiber reinforced plastic (e.g. PA66+6 GF30 or Polyamide 66+6 with a 30% glass-fiber portion) including a connecting piece  3  and two connecting pipes  4  radially protruding from said connecting piece  3 . Any leak-oil pipes to be connected can be attached to the cone-shape end pieces of connecting pipes  4 . The axes A 4  of connecting pipes  4  extend radially to the axis A 3  of connecting piece  3  and form an angle of about 135° with axis A 3  of connecting piece  3 . Axis A 3  of connecting piece  3  coincides, when being in the inserted condition, with axis A 5  of receiving opening  3  as intended. Holding portions  41 ,  42  provided at connecting pipes  4  may be used for positioning the connector  2  with regard to counterpart  6 . 
         [0032]    Connecting piece  3  can be inserted into receiving opening  5  of counterpart  6  in a sealing manner. In the insertion direction of quick-release coupling  1 , a sealing ring  31  is held in a circumferential groove  32  at one end of connecting piece  3 . 
         [0033]    Receiving opening  5  defined in counterpart  6  comprises, starting from an upper surface  60  of counterpart  6 , a chamfer  61  in the entrance region, a snap-in protrusion  62 , a cone-shape widening  63 , an undercut  64 , a cone-shape tapering  65  and a holding area  66 . 
         [0034]    Two identically formed resilient latching or locking arms  7  protrude on diametrically opposed sides of the axis of connecting piece  3  in counter-insertion direction away from connecting piece  3  and can be brought into locking engagement with counterpart  6 . Each of said locking arms  7  comprises a wedge face  71  substantially being formed at the free end of locking arm  7  adjacent to the largest radius of locking arm  7  and facing away from the direction of insertion of connecting piece  3 . Wedge face  71  has an angle of about 45° to axis A 3  of connecting piece  3 . Further, each locking arm  7  is provided at its outside with two wedge faces  72 ,  73  facing away from connecting piece  3  in the direction of insertion, with wedge face  72  being formed adjacent to the greatest radius of locking arm  7 , and wedge face  73  being formed directly adjacent to the cylindrical part of connecting piece  3 . Wedge faces  72 ,  73  each comprise an angle of about 20° with regard to axis A 3  of connecting piece  3 . Due to the different angles of inclination of wedge faces  72 ,  73  with regard to axis A 3  of connecting piece  3 , an insertion force F 2  of connecting piece  3  is smaller than a retraction force F 4  of connecting piece  3 . Glide surfaces  74  and  75  are provided between wedge faces  71 ,  72 ,  73  and extend substantially parallel to axis A 3  of connecting piece  3 , glide surface  74  defining the largest radius of locking arm  7 . The outer contour of locking arm  7  has been adapted to the inner contour of receiving opening  5 . Preferably, wedge faces  71 ,  72 ,  73  are substantially formed as cone envelope portions while glide surfaces  74 ,  75  are substantially formed as cylinder envelope portions. In inner side  76  of locking arm  7  facing towards connecting piece  3  is in the form of a wedge face and is continuously inclined from its low end up to the end of locking arm  7  with regard to the axis of connecting piece  3 , preferably at an angle of about 10°. 
         [0035]    Securing means  8  is preferably integrally formed of plastic or metal and overlaps connector  2  preferably on a side above connecting pipes  4  facing away in counter-insertion direction from connecting piece  3 . To this end, securing means  8  comprises an annular and/or disc-shaped actuating element  80  comprising an actuating surface  81 ,  87  facing away from actuating element  80  in and against the direction of insertion of connecting piece  3 , respectively, as well as two securing portions  82  extending on two opposing sides of connecting piece  3  in the insertion direction of connecting piece  3 , respectively, and being provided at the end of a planar guide portion  83 . Said guide portions  83  each comprise a web  84  centrally protruding radially outwards and extending parallel to axis A 3  of the connecting piece. Guide portions  83  protrude from actuating portion  80  parallel to each other and parallel to the insertion direction of connecting piece  3 . Two snap-in protrusions  85  are provided on opposing sides of the inner circumference  86  of the ring-shaped actuating element  80  and are radially protruding towards the inside. Securing means  8  can be fixed and caught positively to connector  2  in the unlocking and in the locking position via snap-in protrusions  85 . Securing means  8  cooperates with connector  2  in such a manner that securing means  8  is provided at connector  2  in torsion-proof, gliding and captive manner and can be converted by being glided into or against the direction of insertion between the unlocking position in which the locking engagement of quick-release coupling  1  can be unlocked or released and the locking position in which the locking engagement can be guaranteed. 
         [0036]    A fastening means  9  preferably formed as a molded part of plastic or metal is integrally connected or combined to connector  2  or is connected to the residual of connector  2  either in a fixed or in a releasable manner, in order to form a part of connector  2 . Fastening means  9  comprises a substantially cylindrical fastening section  91  having two guiding webs  92  which extend on opposing sides of fastening section  91  parallel to axis A 3  of the connecting piece. Snap-in projections  85  can movably be guided between the locking position and the unlocking position in said guiding webs  92  which are preferably arranged, with regard to axis A 3 , in an equiangular manner to locking arms  7  of connecting piece  3 , or displaced by 90° to locking arms  7  (see  FIGS. 3   a ,  3   b ). Each of said guiding webs  92  comprises two snap-in receptions  96 ,  97  limited by snap-in stages  94 ,  95  into which snap-in projections  85  can be fixed in a locking manner in the locking position and/or in the unlocking position. Additional snap-in receptions may be provided along guiding web  92 . 
         [0037]    The contours and the dimensions of connector  2 , fastening means  9  and securing means  8  match to each other such that securing means  8  can be converted between unlocking and locking position in torsion-proof, tilt-proof and gliding manner. In particular, guide sections  83  have an inner contour matching to the outer contour of connector  2  and glide on the diametrically opposing outer sides of connector  2 . 
         [0038]    The second embodiment of the invention that will be described below with regard to  FIGS. 6 to 9  is substantially based on the first embodiment of the invention. Identical features will be given identical reference numbers used in the first embodiment and it will be refrained from repeating the description. Those features differing from the first embodiment are given inverted commas and will be explained in the following. 
         [0039]    As a modification of the first embodiment, securing means  8 ′ comprises a differently formed, substantially annular and/or disc-shaped actuating element  80 ′ having a substantially oval contour, the ratio of length L 80  (e.g. 20 mm) thereof to the width B 80  (e.g. 10 mm) being approx. 2:1. Two actuating surfaces  81 ′,  87 ′ are respectively facing away from actuating element  80 ′ in or against the direction of insertion of connecting piece  3 . Two securing portions  82  each extend in the insertion direction of connecting piece  3  and are positioned at the end of planar guide portions  83  on two opposing sides of connecting piece  3 . Guide portions  83  each comprise a web  84  centrally protruding radially outwards. Actuating element  80 ′ is arranged on a side facing away from connector  2 ′ in counter-insertion direction of connecting piece  3  and is fixed in a captive manner to connector  2 ′ by means of a lid  88 ′ that can be mounted to connector  2 ′ and is of a substantially oval contour of a ratio of length L 88  to width B 88  of approx. 1.4:1. To this end, lid  88 ′ serves as a securing element for positively fixing or securing actuating element  80 ′ with regard to connector  2 ′. Length L 88  of lid  88 ′ (e.g. 14 mm) preferably extends parallel to an axis A 4  and/or transverse to length L 80  and/or parallel to width B 80  of actuating element  80 ′ and is larger than width B 80  of actuating element  80 ′ by preferably approx. 40%. Lid  88 ′ has been inserted into a corresponding reception of fastening means  9 ′ by means of a pin protruding in the direction of insertion and penetrating actuating element  80 ′ so as to secure same to connector  2 ′ in a captive manner ( FIG. 9   a ). Two lateral supporting arms of inserted lid  88 ′ reach down to the level of connecting pipes  4  and overlap actuating element  80 ′ at the margin-side towards width B 80  thereof ( FIG. 9 ;  FIG. 9   a ). The diameter D 88  of the pin is for example approx. 1.5 mm. The inner circumference of the annular actuating element  80 ′ is provided with two radially inwards projecting snap-in protrusions  85 ′ by which securing means  8 ′ can be positively fixed and latched to connector  2 ′ either in the unlocking or in the locking position. Securing means  8 ′ cooperates with connector  2 ′ in such a manner that securing means  8 ′ is mounted to connector  2 ′ in torsion-proof, movable and captive manner and can be converted by being moved in or against the direction of insertion between the unlocking position in which the locking engagement of quick-release coupling  1  can be unlocked and the locking position in which the locking engagement is secured. 
         [0040]    Fastening means  9 ′ comprises a substantially hollow-cylindrical fastening portion  91 ′ with two guiding webs extending on opposing sides of fastening portion  91 ′ parallel to axis A 3  of connecting piece  3 . Snap-in projections  85 ′ can movably be guided in said guiding webs between the locking and the unlocking position. The guiding webs each comprise an upper snap-in reception  96 ′ which is limited by snap-in stage  95 ′ and lid  88 ′, and a lower snap-in reception  97 ′ below snap-in stage  95 ′. The pin of lid  88 ′ has been inserted into hollow-cylindrical fastening portion  91 ′ so that lid  88 ′ limits the guiding webs to the top and forms the upper stop of the guiding webs. Snap-in protrusions  85 ′ can be fixed in a locking manner in said snap-in receptions  96 ′,  97 ′ in the locking and/or unlocking position. Additional snap-in receptions may be provided along the guiding webs. 
         [0041]    As in the first embodiment, the contours and the dimensions of connector  2 ′, fastening means  9 ′ and securing means  8 ′ match to each other such that securing means  8 ′ can be converted between unlocking and locking position in torsion-proof, tilt-proof and gliding manner. In particular, guide sections  83  have an inner contour matching to the outer contour of connector  2 ′ and glide on the diametrically opposing outer sides of connector  2 ′. 
         [0042]    The third embodiment of the invention that will be described below with regard to  FIGS. 10 and 11  is substantially based on the first and second embodiments of the invention. Identical features will be given identical reference numbers used in the first or second embodiment and it will be refrained from repeating the description. Those features differing from the first or second embodiment are given two inverted commas and will be explained in the following. 
         [0043]    As a modification of the first or second embodiment, securing means  8 ″ comprises another differently formed, substantially seesaw-shaped actuating element  80 ″ having two substantially rectangular actuating surfaces  81 ″,  87 ″ are respectively facing away from actuating element  80 ″ in or against the direction of insertion of connecting piece  3 . Two securing portions  82 ″ each extend in the insertion direction of connecting piece  3  on two opposing sides of connecting piece  3 . Securing portions  82 ″ each are laterally bordered or limited by two guide portions  83 ″ projecting further away from actuating element  80 ″ in the direction of insertion of connecting piece  3  than securing portions  82 ″ themselves and also projecting in radial direction beyond securing portions  82 ″. To this end, securing means  8 ″ is of an inner contour that is adapted to the outer contours of locking arms  7  so that securing means  8 ″ is guided in a gliding manner at locking arms  7  between the unlocking and the locking position in torsion-proof and/or tilt-proof manner. Guide portions  83 ″ laterally glide along locking arms  7  and prevent tilting or torsion of securing means  8 ″ with regard to locking arms  7  and with regard to connector  2 ″. The outer contour of said guide portions  83 ″ matches to the inner contour of the reception opening of a counterpart so as to allow guide portions  83 ″ to be supported on said counterpart and to center connector  2 ″ in said reception opening when in the inserted condition. It may turn out to be useful to have the reception opening being closed, at least section-wise, by said guide portions  83 ″ when securing means  8 ″ is in the locking position. Actuating element  80 ″ is arranged on a side facing away from connector  2 ″ in counter-insertion direction of connecting piece  3  and is secured to connector  2 ″ by means of a lid  88 ″ that can be mounted to connecting pipes  4 ″ of connector  2 ″ in a captive manner. Lid  88 ″ substantially extends in a bridge-shaped form transverse to the longitudinal extension of actuating element  80 ″ and can positively snap on connecting pipes  4 ″ of connector  2 ″ between holding portions  41 ″,  42 ″ via locking portions  89 ″. Snap-in protrusions  85 ″ provided at opposite inner sides of actuating element  80 ″ and projecting inwards and serve to positively fix and lock securing means  8 ″ to connector  2 ″ when in the unlocking and locking position. Securing means  8 ″ cooperates with connector  2 ″ in such a manner that securing means  8 ″ is mounted to connector  2 ″ in torsion-proof, movable and captive manner and can be converted by movement in or against the direction of insertion between the unlocking position in which the locking engagement of quick-release coupling  1  can be unlocked and the locking position in which the locking engagement is secured. 
         [0044]    Fastening means  9 ″ comprises a fastening portion  91 ″ with at least one snap-in reception  97 ″ limited by snap-in stage  95 ″ and lid  88 ″. When in unlocking position, snap-in protrusions  85 ″ can be fixed and caught directly to lid  88 ″ ( FIG. 11 ) and, when in locked position, in snap-in reception  97 ″. 
         [0045]    As in the first and second embodiments, the contours and the dimensions of connector  2 ″, fastening means  9 ″ and securing means  8 ″ match to each other such that securing means  8 ″ can be converted between unlocking and locking position in torsion-proof, tilt-proof and gliding manner. In particular, guide sections  83 ″ have an inner contour matching to the outer contour of connector  2 ″ and glide on the diametrically opposing outer sides of connector  2 ″. 
         [0046]    The preferred application of the invention will be explained below in detail with regard to the first embodiment according to  FIGS. 1 to 5 . The preferred applications of the second and third embodiments largely correspond to the preferred application of the first embodiment and will not be described separately. 
         [0047]    Quick-release coupling  1  according to the invention is inserted in the direction of insertion into receiving opening  5  of counterpart  6 , while securing means  8  is preferably caught in the unlocking position at fastening means  9 . In the unlocking position ( FIG. 1 ), snap-in protrusions  85  are positioned in the first snap-in reception  96  between snap-in stages  94 ,  95  ( FIG. 3   b ). To this end, securing portions  82  are not in engagement with locking arms  7  ( FIG. 3   a ) so that locking arms  7  can be radially urged towards the inside. 
         [0048]    During the insertion of connecting piece  3  into counterpart  6 , connecting piece  3  is first centered in receiving opening  5  by means of wedge faces  72 ,  73  facing away from connecting piece  3 . Without any force being applied in the direction of insertion, wedge faces  72  facing away from connecting piece  3  in the direction of insertion lie flat against snap-in protrusion  62 . Applying an insertion force F 2  causes interaction of locking arms  7  with snap-in protrusion  62  via wedge engagements so that locking arms  7  are radially urged towards the inside, in order to glide with glide surface  75  over snap-in protrusion  62 . Owing to the resilient properties of locking arms  7 , same return to a position projecting away from connecting piece  3  so that locking arms  7  find their way into undercut  64  behind snap-in protrusion  62  where they are caught or locked in place. Wedge faces  71  facing away from connecting piece  3  in counter-insertion direction get into engagement with snap-in protrusion  62  and widening  63 , with locking arms  7  being entirely accommodated in receiving opening  5  and not projecting from receiving opening  5  over surface  60  of counterpart  6 . Thus, quick-release coupling  1  is in locking engagement with counterpart  6 , as shown in  FIG. 4 . 
         [0049]    Securing means  8  is now converted by means of displacement or movement with regard to fastening means  9  in the direction of insertion from the unlocking to the locking position. According to the invention, converting securing means  8  from the unlocking position to the locking position requires a latching force F 1  preferably acting in the direction of insertion to securing means  8  which is larger than insertion force F 2  preferably acting in the direction of insertion to securing means  8 , in order to bring connecting piece  3  into latching engagement with counterpart  6 . In the present case this will be done in that the force F 1  which has to be applied to securing means  8  in the direction of insertion to bring snap-in protrusions  85  from the first snap-in reception  96  between snap-in stages  94 ,  95  to the second snap-in reception  97  below snap-in stage  95  ( FIG. 3   b ) has been set to be larger, due to design features, than the force F 2  which has to be applied to securing means  8  in the direction of insertion, in order to urge locking arms  7  radially towards the inside until same glide together with glide surface  75  over snap-in protrusion  62  and latch behind snap-in protrusion  62 . Latching force F 1  can be determined, e.g. by selecting the length and/or the angle of inclination of the meshing flanks of snap-in protrusions  85  and of snap-in stages  94 ,  95  with regard to axis A 3  of connecting piece  3 . Due to the fact that latching force F 1  has been set to be larger than insertion force F 2 , it can be made sure that connecting piece  3  is in latching engagement with counterpart  6  in any case when securing means  8  is being converted from the unlocking position to the locking position during the insertion. 
         [0050]    When in the locking position ( FIG. 5 ), securing portions  82  cooperate with locking arms  7  in such a manner that locking arms  7  cannot be urged in radial direction towards the inside (see  FIG. 3   a ). Rather are locking arms  7  spread apart from connecting piece  3  and urged deeper into receiving opening  5  by means of web engagement with snap-in protrusion  62 . Thus, there is a secondary securing or locking. Accordingly, connecting piece  3 , when in the locking position, cannot be withdrawn or retracted from receiving opening  5 . When in the locking position, snap-in protrusions  85  are positioned in the second snap-in reception  97  below snap-in stage  95  ( FIG. 3   b ), and actuating surface  81  facing away from connecting piece  3  substantially lines up precisely with the upper side  93  of fastening means  9  facing away from connecting piece  3  ( FIG. 5 ) so that actuating surface  81  and upper side  93  of fastening means  9  lie in one plane. 
         [0051]    By applying an unlocking force F 3  in the counter-insertion direction ( FIG. 5 ), preferably to the actuating surface  87  facing away from actuating element  80  in the insertion direction, securing means  8  can already be converted from the locking position to the unlocking position. In the unlocking position, securing means  8  is not in engagement with locking arms  7  so that locking arms  7  can be urged radially towards the inside. By applying retraction force F 4  in counter-insertion direction, quick-release coupling  1  can be retracted from receiving opening  5 . 
         [0052]    Preferably, the forces behave as follows: |F 3 |≧|F 4 |&gt;|F 1 |&gt;|F 2 | or |F 4 |≧|F 3 |&gt;|F 1 |&gt;|F 2 |. The latching force F 1  preferably is at least 30 N, preferably 30 to 50 N, particularly preferably 40N. In case of a manual handling/mounting, the actuating force should not exceed 30 N. As mounting of the quick-release coupling according to the invention is preferably done in an automated manner, the standard value of 30 N can be exceeded intentionally. 
         [0053]    When in the unlocking position, securing means  8  is again fixed or locked to fastening means  9 , with snap-in protrusions  85  being positioned in the first snap-in reception  96  between snap-in stages  94 ,  95 . Accordingly, securing means  8  can reversibly be converted between the locking and the unlocking positions. 
         [0054]    Owing to the special design of securing means  8 ,  8 ′,  8 ″ and of actuating element  80 ,  80 ′,  80 ″, the inventive quick-release coupling is particularly suitable for automated solutions, as actuating element  80 ,  80 ′,  80 ″ can especially easily be taken and positioned by means of a gripper arm of a mounting apparatus. Due to the contours and dimensions matching to each other, securing means  8 ,  8 ′,  8 ″ can be held to connector  2 ,  2 ′,  2 ″ in a torsion-proof, tilt-proof and captive manner and can be movably converted between unlocking and locking positions. 
         [0055]    The quick-release coupling is not restricted to the described embodiments. Any modifications within the frame of the wording of the claims are conceivable.