Connection system for a medical fluid piping system and connection and coupling unit for such a connection system

Description

[0001] The invention relates to a connection system for a medical fluid line system comprising a connection unit with a connecting body which has a distally arranged Luer outer cone and a through-channel extending coaxially to the Luer outer cone, and a connection unit with a connection body which has a proximally arranged Luer inner cone which is releasably connected in a fluid-tight manner to the Luer outer cone of the connection unit, an external thread which is coaxial to the Luer inner cone and proximally arranged and which is suitable for connection to an internal thread of a Luer lock attachment, and a lumen which extends coaxially to the Luer inner cone and is releasably connected in a fluid-conducting manner to the through-channel by means of the connection of the Luer cones, as well as a connection unit and a connection unit, each of which is designed according to the above embodiments.

[0002] Such a connection system with a connecting unit and a connecting unit is generally known in the field of medical technology, for example from WO 2010 / 071812 A1. The known connecting unit is designed, for example, in the form of an infusion tube connector, and the known connecting unit is designed, for example, in the form of an indwelling venous catheter. The infusion tube connector has a connecting body in the form of a tube connector with a through-channel. A Luer male cone is provided distally on the connecting body, and a fastening section for connection to an infusion tube is provided proximally. The indwelling venous catheter has a connecting body in the form of a catheter connector with a continuously extending lumen and a Luer female cone.The Luer cones can be connected to one another in a fluid-tight manner, which is generally known in the field of medical technology, so that a continuous fluid-conducting connection is achieved, starting from the infusion tube via the through-channel of the tube hub into the lumen of the catheter hub. In the known connection system, a screw connection between an external thread of the catheter hub and an internal thread of the tube hub is provided to secure the Luer cone connection. This screw connection is also referred to as a Luer Lock connection. Such a Luer Lock connection does not close reliably in all cases. On the one hand, the Luer cone connection can spontaneously and unintentionally come loose due to manufacturing tolerances or if the screw connection is tightened too loosely. On the other hand, an overtightened screw connection may no longer be able to be loosened manually, but only with the aid of additional tools.In both cases, patient safety may be compromised.

[0003] The object of the invention is to provide a connection system, a connection unit and a connection unit of the type mentioned at the outset, which have improved properties compared to the prior art and in particular enable a type of securing the Luer cone connection which is an alternative to a Luer Lock connection if required.

[0004] This object is achieved for a connection system of the type mentioned above in that a releasable locking connection is provided between at least one locking element arranged on the connecting body and at least one complementary counter-locking element arranged on the connecting body. The locking connection is designed in such a way that unintentional loosening of the connection of the Luer cones is counteracted, and the counter-locking element and the external thread are designed and arranged in such a way that the connecting unit - when separated from the connecting unit - can be connected by means of a screw connection between the external thread and the internal thread of the Luer lock attachment. The solution according to the invention enables, on the one hand, by means of the provided locking connection, a reliable securing and, if necessary, easy release of the Luer cone connection between the connecting unit and the connecting unit.Secondly, the external thread provided on the connection unit according to the invention ensures that the connection unit can be screwed onto a Luer-Lock attachment instead, for example in the form of a closure cap or the like, if necessary. The solution according to the invention provides for a suitable design and / or arrangement of the external thread and the counter-locking element. The external thread is designed in such a way that a connection to a standard-compliant Luer-Lock attachment and, moreover - if a connection unit according to the invention is to be connected to the connection unit instead of the Luer-Lock attachment - a connection between the locking element and the counter-locking element is ensured, without the external thread preventing, complicating, or blocking the locking connection in the form of an obstacle.For the purpose of the inventive design, the external thread can, for example, be provided with at least one radially and / or axially extending flattened portion, recess, gap, or the like—based on a standard Luer-Lock thread geometry. The counter-locking element can, in particular, be formed by a section of the external thread or be provided as a separate locking geometry on the connector body. The at least one locking element can, for example, be designed in the form of a locking hook, a locking lug, or the like. Accordingly, the counter-locking element can be designed in a complementary manner, for example, in the form of a locking opening, a groove, or the like. It is also possible for the locking and counter-locking elements to be designed in a conversely complementary manner to the above embodiments.

[0005] The object underlying the invention is achieved for a connecting unit of the type mentioned at the outset in that the connecting body has a locking element and a handling section assigned to the locking element, wherein the locking element and the handling section are arranged and / or designed such that the locking element can be displaced by manual handling of the handling section - with reference to a state connected to the connecting unit - relative to the Luer outer cone from a locking position in which the locking element is locked to a counter-locking element of the connecting unit, to a release position in which the locking element releases the counter-locking element. The solution according to the invention therefore enables the locking connection to be easily connected and released manually. The locking element can be connected to the handling section in a force-fitting, form-fitting and / or material-fitting manner.The handling section can preferably be designed in the form of an actuating plate, a slide, a latch, or the like on the connecting body. The locking element can be displaced from the locking position to the release position by means of a push, pull, and / or push actuation of the handling section. The displacement of the locking element can occur relative to the Luer outer cone in an axial, radial, and / or tangential direction. The connecting unit can be designed, in particular, in the form of an infusion tube connector or a syringe. However, the solution according to the invention is not limited to such a design of the connecting unit, but is also suitable for other connecting units for medical fluid conduit systems.

[0006] In an embodiment of the invention, the locking element can be elastically displaced radially outward into the release position by means of a radially inwardly directed elastic displacement of the handling section—with respect to a central longitudinal axis of the connecting unit. The handling section can be designed elastically as such or, instead, can be elastically displaceably supported on the connecting body, for example, by means of a spring element. Accordingly, the locking element can be designed elastically yielding or can be elastically supported on the connecting body. The radially inward displacement of the handling section is preferably effected by means of a manual pressure actuation.

[0007] In a further embodiment of the invention, the connecting body has a flexurally elastic joint section, on which the locking element extends in the distal direction and the handling section in the proximal direction and are pivotably connected in a central longitudinal plane of the connecting unit. The joint section is preferably manufactured in the form of a wall section extending substantially radially relative to the outer Luer cone. The joint section is arranged and configured such that a compressive load on the handling section causes a bending deformation of the joint section in the central longitudinal plane, whereby the handling section is pivoted radially inward relative to the outer Luer cone and the locking element is pivoted radially outward.

[0008] In a further embodiment of the invention, several, preferably two, locking elements are provided, arranged evenly offset from one another in the circumferential direction, each with an associated handling section and a joint section. If two locking elements are provided, offset by 180° from one another in the circumferential direction, this results in particularly ergonomic handling. In such a case, the locking connection can be achieved by actuating the opposing handling sections between, for example, the thumb and index finger.

[0009] In a further embodiment of the invention, the connecting body has at least one guide web extending in the axial direction, which is provided for axial guidance in a complementary guide groove of the connecting unit. This embodiment of the invention allows for simplified alignment of the connecting unit relative to the connecting unit when establishing the locking connection between the locking element and the counter-locking element.

[0010] In a further embodiment of the invention, several, preferably two, guide webs are provided, arranged evenly offset from one another in the circumferential direction. If the guide webs are geometrically different from one another, a circumferentially determined orientation of the connecting unit relative to the connecting unit can advantageously be defined.

[0011] In a further embodiment of the invention, a sealing element is molded onto the front end of the Luer outer cone. The sealing element is preferably made of rubber-elastic material. This embodiment of the invention allows for improved sealing of the Luer cone connection.

[0012] The object underlying the invention is achieved for a connection unit of the type mentioned at the outset in that the connection body has a counter-locking element for releasably locking connection with a locking element of the connection unit, and wherein the counter-locking element and the external thread are arranged and designed such that the connection unit can be connected to the connection unit by means of a locking connection between the counter-locking element and the locking element and - instead - by means of a screw connection between the external thread and an internal thread of the Luer-Lock attachment.

[0013] Accordingly, the solution according to the invention enables, on the one hand, a reliable securing of the Luer cone connection between the connection unit and the connection unit by means of the releasable snap-in connection between the snap-in element and the counter-snap-in element. On the other hand, the solution according to the invention ensures that the connection unit can be screwed using a standard-compliant Luer lock attachment - instead of using a connection unit according to the invention. For this purpose, the solution according to the invention provides a suitable design and / or arrangement of the external thread and the counter-snap-in element. The external thread is designed in such a way that, in particular, a connection of the counter-snap-in element to the snap-in element is ensured without the external thread preventing, complicating, or blocking the snap-in connection in the form of an obstacle. Accordingly, the counter-snap-in element is designed in such a way that a screw connection with the external thread is not blocked or complicating.For the purpose of the design according to the invention, the external thread can be provided, for example - starting from a standard Luer-Lock thread geometry - with a radial and / or axially extended flattening, recess, gap or the like.

[0014] According to the invention, the counter-locking element borders a distal end region of the external thread and is radially set back relative to a diameter, preferably a core diameter, of the external thread. Accordingly, the counter-locking element—when the connection unit is connected to the connecting unit—is arranged on a side of the external thread on the connection body facing away from the connecting unit. This enables, in particular, a Luer-Lock connector to be screwed onto the external thread without hindrance due to the counter-locking element. The radially set back arrangement of the counter-locking element relative to the external thread prevents obstruction of the external thread when screwing or unscrewing the Luer-Lock connector.

[0015] In a further embodiment of the invention, the counter-locking element is designed in the form of a radial groove extending in the circumferential direction, preferably completely around the connector body. When connected to the connecting unit, the locking element engages positively in the radial groove. This prevents accidental release of the Luer cone connection or accidental removal of the connecting unit from the connecting unit, or vice versa.

[0016] In a further embodiment of the invention, the external thread is penetrated in the axial direction by at least one guide groove, which is provided for guiding a guide web of the connecting unit. The external thread is thus interrupted in sections in the circumferential direction.

[0017] As a result, the guide groove ensures the correct alignment of the connector unit relative to the connecting unit, thus improving handling. Furthermore, the positive guidance between the guide groove and the guide bar prevents rotation between the connector unit and the connecting unit.

[0018] In a further embodiment of the invention, the external thread has at least one threaded portion that is radially flattened relative to an outer diameter of the external thread and that is engaged behind by the locking element when the connection unit is connected to the connecting unit. The dimensions, in particular the extent of the radial flattening, of the threaded portion are matched to the dimensions of the locking element. This ensures that the locking element can be guided axially over the flattened threaded portion when the connection unit is connected to the connecting unit. When locked to the counter-locking element, the locking element engages behind the flattened threaded portion.

[0019] Further advantages and features of the invention emerge from the claims and from the following description of preferred embodiments of the invention, which are illustrated with reference to the drawings. Fig. 1 shows in a schematic perspective view an embodiment of a connection system according to the invention, which has an embodiment of a connection unit according to the invention and an embodiment of a connection unit according to the invention, Fig. 2 shows in a schematic perspective view the connection unit according to Fig. 1 , where instead of the connecting unit Fig. 1 a connection unit according to the state of the art is connected to the connection unit with a standard Luer-Lock attachment, Fig. 3 in a schematic longitudinal section in a central longitudinal plane the connection unit according to Fig. 1 , Fig. 4 in a schematic perspective view looking towards a distal end of the connecting unit according to the Fig. 1 and 3 , Fig. 5 in a schematic perspective view the connection unit according to the Fig. 1 and 2, Fig. 6 in an enlarged schematic perspective view the connection unit according to the Fig. 1, 2 and 5 with individual components omitted, Fig. 7 in a schematic perspective view of a further embodiment of a connection unit according to the invention and Fig. 8 in a schematic perspective view of a further embodiment of a connection unit according to the invention.

[0020] According to Fig. 1 A connection system for a medical fluid line system in the form of an infusion arrangement 3 for peripheral venous administration of a medical fluid is provided. The connection system comprises a connection unit 1 and a connection unit 2.

[0021] The connecting unit 1 is designed in the present case in the form of an infusion tube connector, whereby the solution according to the invention is not limited to such a design of the connecting unit. The connecting unit 1 comprises a connecting body 4, which is designed as a single-piece plastic injection-molded component. The connecting body 4 comprises a distally arranged Luer outer cone 5 with respect to an imaginary reference point P and a through-channel 6 extending coaxially to the Luer outer cone 5 ( Fig. 3 ). Furthermore, the connecting body 4 has a proximally arranged fastening section 7, which is formed in the form of a radial widening of the through-channel 6. The fastening section 7 is provided for connection to an infusion tube 8. For the purpose of fastening, the infusion tube 8 can, as shown in Fig. 1 visible, inserted and / or glued into the fastening section 7.

[0022] The connection unit 2 is in the present case designed in the form of an indwelling venous catheter, whereby the solution according to the invention is not limited to such a design of the connection unit 2. The connection unit 2 has a connection body 9 in the form of a catheter hub. The catheter hub 9 has a proximally arranged Luer inner cone 10 with respect to the reference point P, an external thread 11 arranged coaxially to the Luer inner cone 10 and proximally, and a lumen 12 extending coaxially to the Luer inner cone 10 ( Fig. 6 ). A catheter needle 13 is arranged on the catheter hub 9 and is fluidically connected to the lumen 12. In the Fig. 1In the state shown, the outer Luer cone 5 of the connecting unit 1 is detachably connected in a fluid-tight manner to the inner Luer cone 10 of the catheter hub 9. Such a Luer cone connection is generally known in the field of medical technology, with the geometric design of the Luer cones 5, 10 in particular usually being subject to standardization. The Luer cone connection establishes a fluid-conducting connection from the infusion tube 8 via the through-channel 6 into the lumen 12 to an outlet opening 14 of the catheter needle 13.

[0023] Furthermore, the connection system according to Fig. 1 a releasable locking connection 15, 16 between at least one locking element 15 ( Fig. 3, 4 ) and at least one complementary counter-locking element 16 ( Fig. 5, 6). The locking connection 15, 16 is designed in such a way that an unintentional release of the connection of the Luer cones 5, 10 is prevented. In addition, the counter-locking element 16 and the external thread 11 are designed and arranged in such a way that the venous catheter 2, more precisely: the catheter hub 9, can be connected in a state separated from the connecting unit 1 by means of a screw connection S between the external thread 11 and an internal thread of a Luer-Lock hub 17 designed according to the prior art. Such a connection state of the venous catheter 2 is shown in FIG. Fig. 2 Consequently, the design of the counter-locking element 16 and the external thread 11, which will be explained in more detail below, enables the catheter hub 9 to be optionally connected to a connecting unit 1 according to the Fig. 1 , 3 and 4 or a standard Luer-Lock connector 17, as is commonly known in the medical device industry.

[0024] How to proceed based on the Figs. 3 and 4 As can be seen, the connecting unit 1 has a handling section 18 which is assigned to the locking element 15. The handling section is designed in the form of an axially extending, strip-shaped actuating lever 18. The locking element 15 is designed in the form of a locking hook 15 extending axially and in the distal direction from the actuating lever 18. The locking hook 15 and the actuating lever 18 are connected to one another in a materially bonded manner and are elastically pivotably supported on an inner wall 20 of the connecting body 4 by means of a joint section 19. The joint section 19 is designed in the form of a substantially radially extending wall section of the connecting body 4. Starting from the joint section 19, the actuating lever 18 extends in the proximal direction and the locking hook 15 extends in the distal direction. In the Figs. 3 and 4In the configuration shown, the locking hook 15 assumes a locking position in which the locking hook 15 is positively locked to the counter-locking element 16 when the connecting unit 1 is connected to the catheter hub 9. Starting from this position, the locking hook 15 can be elastically displaced radially outwards into a release position by means of a manual pressure actuation of the actuating lever 18 directed radially inwards with respect to a central longitudinal axis 21 of the connecting unit 1, in which release position the locking hook 15 releases the counter-locking element 16. In the release position, the Luer cones 5, 10 can be detached from one another in the axial direction by manually pulling the connecting unit 1 off the indwelling venous catheter 2.

[0025] How to proceed based on the Figs. 3 and 4As can be seen, the connecting body 4 has two locking elements 15 which are mirror-symmetrical to one another. Each of the locking elements 15 is assigned a handling section 18 and a joint section 19. The locking elements 15, together with the respectively assigned handling section 18 and the respective joint section 19, are arranged offset from one another by 180° in the circumferential direction and are otherwise corresponding to one another in terms of their structural design and function. Furthermore, the connecting body 4 has two guide webs 22 which are arranged offset from one another by 180° in the circumferential direction. The guide webs 22 are each provided on a complementary guide groove 23 of the catheter hub 9 for axial guidance. The guide webs 22 are longitudinally extended in the axial direction and are each offset by 90° in the circumferential direction relative to the locking elements 15.To achieve improved sealing of the Luer outer cone 5 against the Luer inner cone 10, a sealing element 24 is also provided. The sealing element 24 has rubber-elastic properties and is molded onto the front end of the Luer outer cone 5.

[0026] How to proceed based on the Figs. 5 and 6 As can be seen, the counter-locking element is designed in the form of a radial groove 16 extending in the circumferential direction on the catheter hub 9. The radial groove 16 borders on a distal end region of the external thread 11. Compared to the external thread 11, the radial groove 16 is set back in the radial direction, so that the external thread 11 projects beyond the radial groove 16 in the radial direction. In order to Fig. 1In order to ensure that the connection of the connection unit 2 to the connecting unit 1 can be connected to the standard Luer-Lock attachment 17, the external thread 11 is specifically designed compared to a standard Luer-Lock thread geometry. On the one hand, the external thread 11 is penetrated in the axial direction by the two guide grooves 23, which are provided for guiding the guide webs 22 of the connecting unit 1. On the other hand, the external thread has flattened thread sections 25. The flattened thread sections 25 are offset by 180° to one another in the circumferential direction and each offset by 90° to the guide grooves 23. Compared to the outer diameter of the external thread 23, the flattened thread sections 25 are radially set back.

[0027] To detachably connect the connecting unit 1 to the connecting unit 2, the units 1, 2 are axially aligned and aligned with the Luer cones 5, 10 facing each other. The guide webs 22 of the connecting unit 1 are placed on the front end against the respective guide groove 23 of the connecting unit 2. The connecting unit 1 and the connecting unit 2 are then moved axially toward each other, with the Luer outer cone 5 penetrating the Luer inner cone 10 and the locking elements 15 being guided over the flattened threaded sections 25. To facilitate the guiding of the locking elements 15 over the flattened threaded sections 25, the handling sections 18 can be pressed radially inward if necessary, although this is not absolutely necessary.After complete penetration of the Luer outer cone 5 into the Luer inner cone 10, a fluid-tight connection is achieved, with the locking elements 15 locking in the radial groove 16.

[0028] To release the Luer cone connection, the previously described movement sequence is carried out essentially in reverse, whereby first the handling sections 18 are pressed radially inwards and thus the positive connection between the locking elements 15 and the radial groove 16 is canceled.

[0029] Connecting and / or disconnecting the connection unit 2 with or from the Luer-Lock attachment 17 is carried out in accordance with a conventional Luer-Lock connection, as is generally known in the field of medical technology.

[0030] Further embodiments of connection units 2a, 2b according to the invention are shown in Fig. 7 and 8 respectively. The embodiments according to the Figs. 7 and 8 essentially correspond to the previously determined Fig. 1, 2 and 5 and 6. To avoid repetition, reference is therefore made to the disclosure of the embodiment according to the latter figures. Only the essential differences between the connection units 2a, 2b and the connection unit 2 will be discussed below. Identical components and sections are provided with identical reference numerals and, to avoid repetition, are not explained separately for each embodiment. Components and sections that have the same function but differ in their structural design are designated by the same reference numerals plus lowercase letters.

[0031] The connection unit 2a is designed in the form of a hose connector. The hose connector 2a provides a connection body 9a, at the distal end of which a hose attachment 26 is arranged. Furthermore, the hose connector 2a differs from the connection unit 2 in that instead of a continuous thread, only a threaded cam 11a is provided. In this respect, a flattening 25 according to Fig. 6 be waived.

[0032] The connecting unit 2b is designed in the form of a disposable cannula. The disposable cannula 2b has a needle hub 9b. Distally on the needle hub 9b, a hypodermic needle 27 is arranged. The proximal region of the needle hub 9b, intended for connection to the connecting unit 1 or - alternatively - the Luer-Lock hub 17, is otherwise essentially identical to the embodiment according to Fig. 7 designed.

Claims

1. Connection system for a medical fluid line system (3) having a connection unit (1) with a connection body (4), which has a distally arranged Luer outer cone (5) and a through-channel (6) extending coaxially with respect to the Luer outer cone (5), and an attachment unit (2) with an attachment body (9) which has a proximally arranged Luer inner cone (10), connected releasably and in a fluid-tight manner to the Luer outer cone (5) of the connection unit (1), a proximally arranged external thread (11) which is coaxial with respect to the Luer inner cone (10) and is suitable for connection to an internal thread of a Luer lock connector (17), and a lumen (12) which extends coaxially with respect to the Luer inner cone (10) and which is releasably connected in a fluid-conducting manner to the through-channel (6) by means of the connection of the Luer cones (5, 10), characterized in that a releasable locking connection (15, 16) is provided between at least one locking element (15) arranged on the connection body (4) and at least one complementary counter-locking element (16) arranged on the attachment body (9), wherein the locking connection (15, 16) is designed in such a way as to counteract an unintentional release of the connection of the Luer cones (5, 10), and wherein the counter-locking element (16) and the external thread (11) are designed and arranged in such a way that the attachment unit (2), in a state when separate from the connection unit (1), is connectable by means of a screw connection (S) between the external thread (11) and the internal thread of the Luer lock connector (17), wherein the counter-locking element (16) is adjacent to a distal end region of the external thread (11) and is radially set back relative to a diameter of the external thread (11) .

2. Connection unit (1) for a connection system according to Claim 1 and / or for releasable operative connection to an attachment unit (2 to 2b) according to any one of Claims 9 to 12, with a connection body (4) which has a distally arranged Luer outer cone (5) and a through-channel (6) extending coaxially with respect to the Luer outer cone (5), characterized in that that the connection body (4) has a locking element (15) and a handling section (18) associated with the locking element (15), wherein the locking element (15) and the handling section (18) are arranged and / or designed in such a way that, by means of a manual handling of the handling section (18) in relation to a state when connected to the attachment unit (2 to 2b), the locking element (15) is displaceable relative to the Luer outer cone (5) from a locking position, in which the locking element (15) is latched onto a counter-locking element (16) of the attachment unit (2 to 2b), to a release position, in which the locking element (15) releases the counter-locking element (16).

3. Connection unit (1) according to Claim 2, characterized in that the locking element (15) is displaceable radially outwardly and elastically to the release position by means of a radially inwardly directed elastic displacement of the handling section (18) relative to a central longitudinal axis (21) of the connection unit (1).

4. Connection unit (1) according to Claim 2 or 3, characterized in that the connection body (4) has a flexible joint section (19), on which the locking element (15) extends in the distal direction and the handling section (18) extends in the proximal direction and on which the locking element and handling section are pivotably hinged in a central longitudinal plane of the connection unit (1).

5. Connection unit (1) according to Claim 4, characterized in that several, preferably two, locking elements (15) are provided, these being uniformly offset with respect to one another in the circumferential direction and each having an associated handling section (18) and a joint section (19).

6. Connection unit (1) according to any one of Claims 2 to 5, characterized in that the connection body (4) has at least one guide web (22) which extends in the axial direction and which is provided for axial guidance in a complementary guide groove (23) of the attachment unit (2 to 2b) .

7. Connection unit (1) according to Claim 6, characterized in that several, preferably two, guide webs (22) are provided, these being uniformly offset with respect to one another in the circumferential direction.

8. Connection unit (1) according to any one of Claims 2 to 7, characterized in that a sealing element (24) is provided that is injected at the end face onto the Luer outer cone (5).

9. Attachment unit (2 to 2b) for releasable operative connection to a Luer lock connector (17) and / or to a connection unit (1) according to any one of Claims 2 to 8, with an attachment body (9 to 9b) which has a proximally arranged Luer inner cone (10), connectable releasably and in a fluid-tight manner to the Luer outer cone (5) of the connection unit (1), a proximally arranged external thread (11, 11a) coaxial with respect to a Luer inner cone (10), and a lumen (12) extending coaxially with respect to the Luer inner cone (10), characterized in that the attachment body (9 to 9b) has a counter-locking element (16) for releasable locking connection to a locking element (15) of the connection unit (1), and wherein the counter-locking element (16) and the external thread (11, 11a) are arranged and designed in such a way that the attachment unit (2 to 2b) is connectable to the connection unit (1) by means of a locking connection (15, 16) between the counter-locking element (16) and the locking element (15) and - instead - by means of a screw connection (S) between the external thread (11, 11a) and an internal thread of the Luer lock connector (17), wherein the counter-locking element (16) is adjacent to a distal end region of the external thread (11, 11a) and is radially set back relative to a diameter of the external thread (11, 11a).

10. Attachment unit (2 to 2b) according to Claim 9, characterized in that the counter-locking element is designed in the form of a radial groove (16) extending in the circumferential direction, preferably completely about the circumference, on the attachment body (9 to 9b) .

11. Attachment unit (2 to 2b) according to Claim 9 or 10, characterized in that the external thread (11, 11a) is traversed in the axial direction by at least one guide groove (23), which is provided for guiding a guide web (22) of the connection unit (1).

12. Attachment unit (2) according to any one of Claims 9 to 11, characterized in that the external thread (11) has at least one thread section (25) radially flattened with respect to an external diameter of the external thread (11), which thread section, in a state with the attachment unit (2) connected to the connection unit (1), is engaged from behind by the locking element (15).