Patent Publication Number: US-2013249209-A1

Title: Plug-in connection arrangement

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the priority of German patent application DE 10 2012 005 930.2, filed Mar. 26, 2012. The entire content of this priority application is incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     The present invention relates to a plug-in connection arrangement for releasably connecting fluid lines, said plug-in connection arrangement comprising a basic body which has a supply line and an insertion opening, wherein the basic body is connectable to one of the fluid lines, and wherein a connecting piece which is connectable to a second of the fluid lines, can be plugged onto the supply line in order to form a tight connection with the supply line, and having a fixing element which is accommodated in the insertion opening and is fixed in the insertion opening in the axial direction of the supply line in order to secure the connecting piece in a fitting position. 
     From the prior art, in particular from the field of combustion engine engineering, it is known to connect fluid lines together by means of plug-in connections for pumping media, in particular fuel. In this case, it is of particular interest that the fluid lines form a tight connection which can be loaded by an internal pressure. In addition, it is important that the plug-in connections are realized in a universal manner, that is that the plug-in connection is able to be connected to several lines in order to reduce the number of different components. 
     In the case of plug-in connections in the field of automobiles, it is particularly important that the plug-in connections form a reliable and long-lived connection and at the same time are able to be released in a non-destructive manner in the event of repair. In addition, it is of interest that the plug-in connections are mountable in a simple and rapid manner in order to reduce the production costs of the entire assembled unit in this manner. Usually, these types of plug-in connections are realized by means of two pipe portions which can be connected one on top of the other and are fixed to each other by means of a screw or clamping connection. In this case, the pipe portions are first of all slipped one on top of the other and are moved into a final fitting position. Once the final fitting position has been reached, a clamping or screw connection element is attached to the pipe portions which are slipped one on top of another in order to connect the pipe portions in a fixed manner. 
     A disadvantage, in this case, is that these types of plug-in connections are generally technically expensive, have to be assembled taking up a large effort of time and money and the correct assembly has to be checked with a large effort of time and money. 
     BRIEF SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a plug-in connection arrangement for the releasable connection of fluid lines, which forms a reliable connection between the fluid lines and at the same time being able to be mounted costing a small amount of time and money and being able to be checked costing a small amount of time and money. 
     According to a first aspect of the invention a plug-in connection arrangement is provided for releasably connecting fluid lines, comprising a basic body which has a supply line and a insertion opening, wherein the basic body is connectable to one of the fluid lines, and wherein a connecting piece, which is connectable to a second of the fluid lines, can be plugged onto the supply line in order to form a tight connection with the supply line, a fixing element which is accommodated in the insertion opening and is fixed in the insertion opening in the axial direction of the supply line in order to secure the connecting piece in a fitting position, and a connection element which is mounted on the supply line so as to be movable in the axial direction and prestresses the fixing element in the radial direction in an axial position. 
     According to a second aspect of the invention a plug-in connection arrangement is provided for releasably connecting fluid lines, comprising a basic body which has a supply line and a insertion opening, wherein the basic body is connectable to one of the fluid lines, and wherein a connecting piece, which is connectable to a second of the fluid lines, can be plugged onto the supply line in order to form a tight connection with the supply line, a fixing element which is accommodated in the insertion opening and is fixed in the insertion opening in the axial direction of the supply line in order to secure the connecting piece in a fitting position, wherein the basic body has an accommodating portion which is formed between an axial stop of the basic body and the insertion opening, wherein a connection element is insertable into the accommodating portion by means of the connecting piece, and wherein the connection element in the accommodating portion is compressed in such a manner that the connecting piece is fixed coaxially with respect to the supply line. 
     According to a third aspect of the invention a plug-in connection arrangement is provided comprising a basic body which has a supply line and a insertion opening, wherein the basic body is connectable to one of the fluid lines, and wherein a connecting piece, which is connectable to a second of the fluid lines, can be plugged onto the supply line in order to form a tight connection with the supply line, a fixing element which is accommodated in the insertion opening and is fixed in the insertion opening in the axial direction of the supply line in order to secure the connecting piece in a fitting position, and a connection element which is mounted on the supply line so as to be movable in the axial direction, wherein the connection element is movable in a fitting position by means of the connecting piece, wherein the connection element has an extension which protrudes in the axial direction and projects into an opening of the basic body in the fitting position in order to indicate the position of the connection element. 
     According to a fourth aspect of the invention a plug-in connection arrangement is provided for releasably connecting fluid lines, comprising a basic body which has a supply line and a insertion opening, wherein the basic body is connectable to one of the fluid lines, and wherein a connecting piece, which is formed as a connection tube is connectable to a second of the fluid lines, can be plugged onto the supply line in order to form a tight connection with the supply line, a fixing element which is accommodated in the insertion opening and is fixed in the insertion opening in the axial direction of the supply line in order to secure the connecting piece in a fitting position, and a connection element which is mounted on the supply line so as to be movable in the axial direction between a first and a second axial position, wherein the fixing element abuts against the connection element in the first axial position and wherein the connection  element prestresses the fixing element in the radial direction in the first axial position, and wherein the connection element is movable into a second axial position by means of the connecting piece such that the fixing element is released from the connection element, and abuts against the connecting piece in order to secure the connecting piece in the axial direction in the fitting position. 
     By, according to the first aspect of the present invention, providing a connection element which is mounted on the supply line so as to be movable in the axial direction and prestresses the fixing element in the radial direction in an axial position, the connecting piece can be connected to the supply line through simple sliding onto the supply line. As the connection element already prestresses the fixing element in the radial direction, the connection element can be slid further onto the supply line without the radial prestressing force having to be applied during the sliding-on movement. As a result, the time and money spent on assembly can be reduced as the subsequent assembly step of the fixing element is omitted and at the same time the force for sliding on the connecting piece is reduced. 
     By, according to the second aspect of the present invention, the connection element being compressed in the accommodating portion and the connecting piece being fixed coaxially with respect to the supply line, simply by sliding the connecting piece onto the supply line the connecting piece can be centered and fixed, as a result of which the time and money spent on assembly is reduced and at the same time the connecting piece can be mounted on the supply line in an optimum position. 
     By, according to the third aspect of the present invention, providing a connection element which is provided on the supply line so as to be movable in the axial direction, and which is movable into the fitting position by means of the connecting piece and at the same time has a protruding extension which projects into an opening of the basic body in the fitting position, the position of the connection element can be indicated. In this case, the protruding extension at the same time indicates whether a connection element is mounted and whether the connecting piece has been moved into the final assembly position. As a result, using simple technical means it is possible to check whether the connecting piece has been moved into the final assembly position, as a result of which the assembly becomes generally more reliable. 
     In a particular embodiment of the first aspect of the present invention, the connection element is movable into a second axial position by means of the connecting piece such that the fixing element abuts against the connecting piece and secures the connecting piece in the axial direction. 
     This means that the connecting piece can be fixed simply by plugging onto the supply line, as a result of which the subsequent assembly step for the fixing element is omitted and the effort of time and money spent on the connecting piece is reduced. 
     In this case, it is particularly preferred when the basic body has an axial stop for the connecting piece, and wherein the connection element in the second axial position is arranged between the axial stop and the insertion opening. 
     This means that a fitting position of the connecting piece can be defined and the fixing element can be moved to abut against the connecting piece in a reliable manner such that a reliable and fixed fitting position is achieved. 
     In the case of the second aspect of the present invention, it is particularly  preferred when the connection element has a centering portion with an outer radius which is greater than an inner radius of the accommodating portion. 
     This ensures that the connection element is not moved unintentionally or incorrectly into the fitting position as a defined force has to be exerted in the axial direction by the connecting piece in order to move the connection element into the accommodating portion. 
     In this case, it is particularly preferred when the accommodating portion is formed coaxially with respect to the supply line. 
     This means that simply by inserting the connection element, the connecting piece can be fixed and centered coaxially with respect to the supply line. 
     In the case of the third aspect of the present invention, it is particularly  preferred when the connection element is arranged between an axial stop of the basic body and the insertion opening in the fitting position. 
     This means that a fitting position of the connection element is defined in relation to the basic body, as a result of which the fitting position of the connection element and of the connecting piece can be indicated in a reliable manner. 
     It is generally preferred when the connection element has a stop element which forms with the basic body a second axial stop for the connection element, and wherein an idle path is formed between the first axial stop and the second axial stop. 
     This means that the connection element can be pre-mounted in a captive manner on the basic body. 
     In this case, it is particularly preferred when the connection element is mounted on the supply line between the first and the second axial stop so as to be movable in the axial direction. 
     This means that the connection element can be moved back and forth in an arbitrary manner between the two axial positions during assembly and during disassembly, as a result of which assembly and non-destructive disassembly is generally simplified. 
     It is additionally preferred when a fitting position is formed on the first axial stop and a pre-assembly position is formed on the second axial stop. 
     Through said definition of the fitting position and of the pre-assembly position, the mounting of the fixing element and of the connection element is generally simpler and more reliable as the connection element can only be moved back and forth between the two relevant positions. 
     It is particularly preferred when the stop element is formed as a locking element which protrudes in the axial direction and projects into an opening of the basic body. 
     This means that a second axial stop, which can be mounted simply by sliding the connection element onto the basic body, can be provided using simple means. 
     It is generally preferred when the connection element has at least one tappet element which connects the connection element to the connecting piece so as to be releasable in the axial direction. 
     This means that the disassembly of the connecting piece can be simplified as when pulling off or releasing the connecting piece, the tappet element moves the connection element out of the fitting position into the pre-assembly position. 
     In this case, it is particularly preferred when the connecting piece is releasable from the connection element by means of a predefined pulling force. 
     This means that when the pre-assembly position is reached, the connecting piece can be simply and reliably released from the connection element by increasing the pulling force. 
     In this case, it is particularly preferred when the tappet element is formed as a locking element. 
     This means that using simple means it is possible to realize a releasable  connection which is releasable by means of a predefined pulling force. 
     It is obvious that the above-mentioned features and the features yet to be explained below can be used not only in the combination provided in each case, but also in other combinations or standing alone without departing from the framework of the present invention. 
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
     Exemplary embodiments of the invention are shown in the drawing and are explained in the following description, in which, in detail: 
       FIG. 1  shows a schematic perspective view of a plug-in connection arrangement with a connection element; 
       FIG. 2  shows a perspective detailed view of the connection element; 
       FIG. 3   a, b  show a schematic sectional view of the plug-in connection arrangement of  FIG. 1  to explain the function of the connection element; 
       FIG. 4   a, b  show schematic sectional views of the plug-in connection arrangement of  FIG. 1  to explain the centering function of the connection element; 
       FIG. 5   a, b  show a schematic view of a portion of the basic body of the plug-in connection arrangement to explain a positional indicator and a stop element; 
       FIG. 6   a, b  show a schematic sectional view of the plug-in connection arrangement from  FIG. 1  to explain a tappet element; 
       FIG. 7  shows an exploded perspective representation of the plug-in connection arrangement of  FIG. 1 ; 
       FIG. 8  shows a perspective representation of the plug-in connection arrangement with the connecting piece slid on; and 
       FIG. 9  shows a schematic perspective representation of a rear side view of the plug-in connection arrangement of  FIG. 1 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A schematic representation of a plug-in connection arrangement is shown in  FIG. 1  and is generally designated by  10 . 
     The plug-in connection arrangement  10  has a basic body  12  with a supply line  14  and two connecting pieces  16 ,  18 . A radial insertion opening  20  in which a fixing element  22  is accommodated is formed in the basic body  12 . At a distal end, the supply line  14  has a circumferential groove  24 , in which an O-ring seal  26  is accommodated. On a side opposite the supply line  14 , the basic body  12  has an assembly portion  28  which is formed as a horizontal face perpendicular with respect to a longitudinal axis of the supply line  14 . On its surface, the assembly portion  28  has a rib profile. Two wings  30 ,  32 , which are formed in the same plane as the assembly portion  28 , extend from the assembly portion  28 . The wings  30 ,  32  are formed above the connecting pieces  16 ,  18  and cover the connecting pieces  16 ,  18  when the supply line  14  is viewed in an axial direction. 
     A connection element  34  is arranged on the supply line  14 . The connection element  34  is mounted on the supply line  14  so as to be movable in the axial direction. The connection element  34  is formed in a substantially ring-shaped manner and has two contact portions  36 , which form two circumferential portions of the connection element  34 . A projection  38 , which protrudes in the radial direction in relation to the respective contact portion  36 , is formed in each case on the contact portions. 
     Two extensions  40 , which extend in the axial direction, are formed on the connection element  34 . The extensions  40  are formed as bent elements coaxially with respect to the supply line  14 . In addition, the connection element  34  has two stop elements  42  which extend in the axial direction. The stop elements  42  protrude in the axial direction in relation to the contact portion  36 . The stop elements  42  have in each case a catch  44  which extends in the radial direction in relation to the stop element  42 . 
     In addition, the connection element  34  has two tappets  46  which extend in the axial direction. The tappets  46  extend in a direction which is opposite to the continuations  40  and the stop elements  42 . 
     The fixing element  22  is realized as a resilient clamp which is formed open on one side. The clamp is preferably formed from a resilient material such as, for example, metal or plastics material. The fixing element  22  has two fixing portions  48  which are realized on two opposite sides and have a circular form at least in portions. In addition, the fixing element  22  has two insert portions  50  which connect to the fixing portions  48 . The insert portions are formed in a substantially straight manner and together form a funnel form on the open side. The fixing element  22  also has a gripping portion  51  which is formed on one side of the fixing element  22  opposite the insert portions  50  or the open side. A stop portion  52 , which forms a radial stop with an element of the basic body  12 , is also realized on the fixing element  22  in the region of the gripping portion  51 . 
     The radial insertion opening  20  is formed between a first guiding face  54  and a second guiding face  55 , which are formed perpendicular with respect to a longitudinal axis of the supply line  14  and are located opposite one another. The fixing element  22  is accommodated between the guiding faces  54 ,  55  and is fixed in the axial direction. The guiding face  54  protrudes in the radial direction in relation to the guiding face  55  in order to make the insertion of the fixing element  22  easier. A stop element  56 , against which the stop portion  52  of the fixing element strikes when being pulled out, is arranged on a radial end of the guiding face  54 . This means that a captive situation is formed for the fixing element  22 , as a result of which the fixing element can be prevented from being released completely when being pulled out of the insertion opening  20 . 
     An opening  58 , which extends in the axial direction of the supply line  14 , is formed in the basic body  12  between the radial insertion opening  20  and the assembly portion  28 . In addition, a stop  60  is formed in the region of the opening  58 . The opening  58  is formed in an arcuate and coaxial manner with respect to the supply line  14 . The opening  58  is formed such that the extensions  40  can project through the opening in order to indicate a fitting position of the connection element  34 , as is explained in more detail below. The stop element  42  can also project through the opening  58  such that the catch  44  engages behind the stop  60  and consequently forms an axial stop for the connection element  34 . 
     The plug-in connection arrangement  10  generally serves for the purpose of connecting fluid lines together. To this end, two fluid lines are connected to the connecting pieces  16 ,  18  and a further fluid line, which is connected to a connecting piece which is not shown in  FIG. 1 , is connected to the basic body  12  by the connecting piece being slipped onto the supply line  14  and being secured in a fitting position by means of the fixing element  22 . In other words, the supply line  14  is inserted into the connecting piece which is not shown here and is secured by means of the fixing element  22 . 
     Before the connecting piece is slipped onto the supply line  14 , the connection element  34  is arranged in a pre-assembly position in the region of the radial insertion opening  20  and the fixing portions  48  of the fixing element  22  are moved to abut against the contact portions  36  and are radially prestressed. The connection element  34 , pre-assembled in this manner, is then moved into a final assembly position as the connecting piece is slipped on and the prestressed fixing portions  48  abut against the connecting piece in order to fix said connecting piece in the end assembly position. 
     The connecting pieces  16 ,  18  are arranged in an angled manner with respect to one another. This is brought about by a particular fitting position of the plug-in connection arrangement  10  and enables hoses which are connected to the connecting pieces  16 ,  18 , to be bent in a defined manner. In an advantageous manner, this means that the operating step in which the connecting hoses have to be bent in order to be connected to the connecting pieces  16 ,  18  is omitted when the plug-in connection arrangement  10  is mounted. 
     The fixing element  22  is fixed in the axial direction in the radial insertion opening  20  and is mounted so as to be movable in the radial direction. This means that the fixing element can fix the connecting piece in the axial direction and can be guided in and out in the radial direction. 
       FIG. 2  shows a perspective view of the connection element  34  in detail. The connection element  34  is ring-shaped and has the contact portions  36 , against which the fixing portions  48  are moved to abut in the pre-assembly position. The contact portions  36  are formed in each case on an arcuate element which protrudes in an axial direction. A projection  38 , which extends in each case in the radial direction in relation to the contact portion  36 , is formed in each case on the contact portions  36 , wherein a substantially conical face being formed in portions by the respective projection. The projections  38  serve for the purpose of fixing the connection element  34  in a fitting position in relation to the basic body  12  and of fixing and centering an axial end of the connecting piece to be connected, as is explained in more detail below. 
     The extensions  40  and the stop elements  42  extend in the axial direction. In a fitting position of the connection element  34 , the extensions  40  protrude into the opening  58  and can consequently indicate the fitting position of the connection element  34 . Furthermore, the stop elements  42  also protrude through the opening  58 , and their catches  44  form with the stop  60  an axial stop for the connection element  34 . In addition, the tappets  46 , which extend in an axial direction opposite to the extensions  40  and the stop elements  42 , are formed on the connection element  34 . The tappets  46  in each case have an inwardly directed catch (not shown here) in order to form a releasable connection with a groove of the connecting piece, as is explained in more detail below. 
     The connection element  34  is formed separately from the basic body  12 , separately from the connecting piece and separately from the fixing element  22 . 
       FIG. 3   a  and b show schematic sectional views of the plug-in connection  arrangement  10  to explain the method of operation of the plug-in connection arrangement  10 . Identical elements are designated by identical reference numerals, only the characteristic features being explained here. 
     In  FIG. 3   a , a connecting piece  62  is slipped onto the supply line  14  coaxially with respect to the supply line  14 . The supply line  14  has an inner fluid line  64  which is connected to inner lines of the connecting pieces  16 ,  18  and forms a tee joint. An opening  66 , which surrounds the supply line  14 , is formed in the basic body  12 . The opening  66  is formed in the guiding face  54 . The connection element  34  is shown in the pre-assembly position in  FIG. 3   a  such that the fixing element  22  or the fixing portions  48  abut against the respective contact portions  36  of the connection element  34 . In this position, the connection element  34  widens the fixing element  22  in the radial direction and prestresses the fixing portions  48  in the radial direction. As the fixing element  22  is secured between the guiding faces  54 ,  55  in the axial direction, the fixing portions  48  are only able to move in the radial direction. 
     The connecting piece  62  is inserted into the opening  66  such that an axial end of the connecting piece  62  abuts against the connection element  34 . The connecting piece  62  has an end portion  68  which is formed at the axial end of the connecting piece  62 . The connecting piece  62  also has a groove  70  which is realized, at least in portions, circumferential on the connecting piece  62 . The groove  70  connects directly to the end portion  68  in the axial direction of the connecting piece  62 . In the preassembly position shown in  FIG. 3   a , the end portion  68  is surrounded circumferential by the contact portions  36 . 
     An axial stop  72  is also formed on the basic body  12 . The axial stop  72  is formed as a face perpendicular with respect to a longitudinal axis of the supply line  14 . An accommodation portion  74 , which can be formed in a cylindrical or conical manner and into which the connection element  34  projects in part in the position shown in Fig,  3   a,  is additionally formed in the basic body  12 . 
     The connecting piece  62  is basically slipped onto the supply line  14  in a slip-on direction, as is indicated by an arrow  76 . 
     In  FIG. 3   b , an end position or a fitting position of the connection element  34  and of the connecting piece  62  is shown. Identical elements are designated with identical reference numerals, only the characteristic features being explained here. 
     When, proceeding from the pre-assembly position shown in  FIG. 3   a , the connecting piece  62  is pushed in further in the direction of the arrow  76 , the contact portions  36  release the fixing portions  48  such that they move inward as a result of the radial prestressing and come to rest in the groove  70  of the connecting piece  62 . 
     As the fixing element  22  is fixed between the guiding faces  54 ,  55  in the axial direction, the connecting piece  62  is also fixed in the axial direction in said fitting position. The connection element  34  is abutted against the axial stop  72  in the axial direction such that a defined axial position is achieved. In addition, the projections  38  abut against the accommodating portion  74  such that the connection element  34  is centered in a coaxial manner. 
     A tight connection is formed between the supply line  14  and the connecting piece  62  by means of the O-ring seal  26  in said fitting position such that the fluid lines are connected together in a tight manner. 
     By the connection element  34  already prestressing the fixing element  22  in the radial direction in the pre-assembly position, which is shown in  FIG. 3   a , and only a small force having to be exerted in the direction of the arrow  76  by means of the connecting piece  62  in order to move the connection element  34  into the end position or the fitting position, the time and money spent on assembly for plugging on and fixing the connecting piece  62  is clearly reduced. The connecting piece  62  is slipped on or the supply line  14  is inserted by means of a force which is exerted onto the assembly portion  28 . 
       FIG. 4   a, b  show a schematic sectional view of the plug-in connection arrangement  10  to explain the centering of the connecting piece  62  by means of the connection element  34 . Identical elements are designated with identical reference numerals, only the characteristic features being explained here. 
       FIG. 4   a  shows the connection element  34  in the pre-assembly position in which the connecting piece  62  has already been moved to abut against the connection element  34 . The outer diameter of the projections  38  is larger than the inner diameter of the accommodating portion  74 . In so far as the connecting piece  62  is pushed into the basic body  12  in the direction of the arrow  76 , the connection element  34  abuts against the axial stop  72 , the projections  38  being pressed inward in the radial direction at the same time. 
       FIG. 4   b  shows the fitting position of the connection element  34  and of the connecting piece  62 . The projections  38  are pressed radially inward in said position, as a result of which an inner circumferential face  78  of the connection element  34  is moved to abut against the end portion  68  and fixes and centers the connecting piece  62  coaxially with respect to the supply line  14 . This means that a particularly precise fitting position of the connecting piece is achieved by means of the connection element  34 . 
       FIGS. 5   a  and b show schematic representations of views of details of the basic body  12  to explain the method of operation of the extensions  40  and of the stop element  42 . 
       FIG. 5   a  shows the connection element  34  in the pre-assembly position shown in  FIGS. 3   a  and  4   a . The extension  40  does not project through the opening  58  in said pre-assembly position. The stop element  42  projects in part through the opening  58 , far enough for the catch  44  to be able to engage just behind the stop  60  and consequently form an axial stop with the basic body  12 . The catch  44  serves the purpose of not allowing the connection element  34  to be moved further away from the basic body  12  in so far as it has reached the pre-assembly position. In other words, the connection element  34  is secured in said pre-assembly position in so far as the fixing element  22  is fixed on the contact portions  36 . 
     In so far as the connecting piece  62  is moved in the direction of the arrow  76  from  FIGS. 3   a  and  4   a , the connection element  34  is moved into the end position and the extension  40  is pushed right through the opening  58 , as is shown in  FIG. 5   b . The stop element  42  is also moved upward right through the opening  58 . In the position shown in  FIG. 5   b , the connection element  34  is moved to abut against the axial stop  72  such that the extension  40  and the stop element  42  are no longer able to be moved right through the opening  58 . In said second axial position of the connection element  34 , the end assembly position is achieved. An idle path  80 , which is shown schematically in  FIG. 5 , is formed between the catch  44  and the axial stop  72 . 
     Consequently, the final assembly position of the connection element  34  is indicated by means of the extension  40  using simple means such that the correct assembly of the connection element  34  and of the connecting piece  62  is able to be checked from the outside. The axial movement of the connection element  34  is restricted by the stop element  42 , the axial stop  72  and the idle path  80  formed between said two stops such that the connection element  34  is only able to move between the pre-assembly position and the final assembly position. 
       FIG. 6   a  and b show schematic sectional views of the plug-in connection arrangement  10  to explain the method of operation of the tappets  46 . Identical elements are designated with identical reference numerals, only the characteristic features being explained here. 
     Each of the tappets  46  has a locking element  82  which extends radially inward. In the fitting position of the connection element  34  shown in  FIG. 6   a , the locking elements  82  are arranged in the grooves  70  of the connecting piece  62 . In so far as the connecting piece  62  is to be disassembled, the fixing element  22  is initially released and the connecting piece  62  is then pulled from the supply line  14  in the direction of an arrow  84 . When the grooves  70  strike against the locking elements  82 , the connection element  34  is moved out of the fitting position in the direction of the arrow  84  and is moved back into the pre-assembly position, as is shown in  FIG. 6   b . In said position, the extension  40  does not project right through the opening  58  such that the pre-assembly position can easily be seen from the outside. In addition, the stop element  42  is moved to abut against the stop  60  in said position. When disassembling the connecting piece  62 , the connection element  34  can easily be moved back into the preassembly position by means of said entrainment means  46  and once again can be fixed there by the fixing element  22  in order to be moved into the fitting position once again when the connecting piece  62  is mounted. 
     In order to release the connecting piece  62  totally from the supply line  14 , the pulling force has to be increased in the direction of the arrow  84  in the position shown in  FIG. 6   b  such that the tappets  46  are pivoted radially outward and the locking elements  82  release the connecting piece  62 . Consequently, the connecting piece  62  is able to be released from the supply line  14  by means of a predefined pulling force. 
     An exploded representation of the plug-in connection arrangement  10  is shown in perspective in  FIG. 7 . Identical elements are designated with identical reference numerals, only the characteristic features being explained here. 
     First of all, the fixing element  22  is inserted radially into the insertion opening  20  until the fixing portions  48  are arranged coaxially with respect to the longitudinal axis of the supply line  14 . The connection element  34  is then slipped onto the supply line  14  in the axial direction of the arrow  76  until the catch  44  is guided right through the opening  58  and engages behind the stop  60 . In said position, the fixing portions  48  have been moved radially outward and consequently prestressed in the radial direction. In said position, slipping on the connecting piece  62  is easily possible and by expending little force as the necessary prestressing of the fixing element  22  has already been effected by the connection element  34 . The connection element  34  is fixed in said pre-assembly position by the radial pre-stressing of the fixing element  22  and by the axial stop which is formed by the catch  44  and the stop  60 . 
       FIG. 8  shows the plug-in connection arrangement  10  in perspective with a mounted connecting piece  62 . Identical elements are designated with identical reference numerals, only the characteristic features being explained here. 
     By means of the extensions  40  and the stop element  42 , which clearly project through the opening  58 , it can be seen that the connection element  34  is situated in the fitting position. The connecting piece  62  has been completely slipped onto the supply line  14 , the fixing element  22  already being situated in a disassembly position.  In said position, the stop portion  52  is moved to abut against the stop  56  such that in said disassembly position the connecting piece  62  can already be pulled down in the axial direction from the supply line  14 . This means that a non-destructive, simple disassembly of the connecting piece  62  is possible. 
       FIG. 9  shows a schematic representation in perspective of a rear side view of the plug-in connection arrangement  10 . Identical elements are designated with identical reference numerals, only the characteristic features being explained here 
     In this position, the extensions  40  and the stop element  42  indicate that the connection element  34  is situated in the pre-assembly position. The insert portions  50  of the fixing element  22  are inserted completely into the radial insertion opening such that they project out of the radial insertion opening again on the opposite side. In said position, consequently, the connection element  34  is fixed in the preassembly position by means of the fixing portions  48  such that the plug-in connection arrangement  10 , provided in such a manner, is ready for assembly with the connecting piece  62 . 
     It is obvious that the plug-in connection arrangement  10  can also have just one of the connecting pieces  16 ,  18 , or, however, more than two of the connecting pieces  16 ,  18 . 
     The plug-in connection arrangement  10  is preferably used as an overflow oil line in order to return surplus fuel from a combustion engine back into the fuel tank in order to supply it to the combustion engine again.