EP1642094A2

EP1642094A2 - Device for administering a liquid product

Info

Publication number: EP1642094A2
Application number: EP04740259A
Authority: EP
Inventors: Erich Imhof; Daniel Peter
Original assignee: Disetronic Licensing AG
Current assignee: F Hoffmann La Roche AG; Roche Diabetes Care GmbH
Priority date: 2003-07-03
Filing date: 2004-06-24
Publication date: 2006-04-05
Also published as: DE10330094A1; WO2005002652A3; WO2005002652A2; DE10330094B4; CA2525797A1; JP2009513167A; US20060151545A1; US7798377B2

Abstract

The invention relates to an infusion or injection device for the preferably metered administration of a liquid product, comprising a receptacle for storing the product that preferably contains a medical or therapeutic agent, a piston plug which can be axially moved in an advancing direction towards an outlet of the receptacle by an output member so as to cause product to be dispensed from the receptacle, and a mechanism for detachably connecting the piston plug to the output member. Said connecting mechanism secures the connection between the piston plug and the output member against axial displacement of the output member relative to the piston plug while the connection can be removed by means of relative twisting between the piston plug and the output member. The inventive device is characterized in that the connecting mechanism is designed such that the connection between the piston plug and the output member can be established by axially displacing the output member and the piston plug relative to each other.

Description

Device for administering a liquid product

The invention relates to a device for the preferably metered administration of a liquid and preferably containing a medicinal or therapeutic active ingredient, very particularly preferably for the administration of insulin for the treatment of diabetes patients.

For metered administration, liquids which contain a medical or therapeutic active substance are preferably stored in a fluid container in which a piston stopper is mounted so as to be axially displaceable. The piston plug is axially displaced by an output member of a drive mechanism toward an outlet of the fluid container in order to cause fluid to be released from the fluid container. It is preferred that the fluid container is interchangeable. This requires a connection mechanism for releasably connecting the piston plug to the output member. For an exact dosing of the fluid to be administered, the connection mechanism should be designed in such a way that the connection between the piston plug and the output member is blocked against axial displacement of the output member relative to the piston plug, in order to prevent, for example, self-emptying of the fluid container due to the so-called siphoning effect.

It is known from the prior art to provide the driven member with a bead which engages in an undercut on the back of the piston plug. Such a connection is difficult to establish and detachable again. Is from the prior art also known to provide the piston plug and the front end of the output member each with a thread and a counter thread, so that a connection is made by screwing the output member to the piston plug and this can be released again by unscrewing the output member from the piston plug. The ampoule with the piston stopper held therein is usually screwed to the output member by hand. The screwing is time consuming. Screwing is problematic if the position of the output member and piston plug do not match. During screwing, liquid can therefore be poured out or air drawn into the fluid container. In particular, sucking in air should be avoided, as this can lead to complications in therapy.

The object of the invention is to provide a device for the preferably metered administration of a product with a connecting mechanism which is designed in such a way that the connection between the piston plug and the output member can be easily established and released again.

This object is achieved by a device with the features according to claim 1. Advantageous embodiments are the subject of the dependent claims.

According to the invention, starting from a device with a connecting mechanism in which the connection between the piston plug and the driven member can be released again by a relative rotation between the piston plug and the driven member, the connecting mechanism is designed such that the connection between the piston plug and the driven member is moved towards the piston plug by axially advancing the driven member can be produced. It is advantageous that the drive mechanism of the injection or infusion device in which the fluid container is to be used does not need to be specially designed for the exchange of the fluid container. Rather, the axial feed movement of the driven member, for which the mechanics of the injection or infusion device is designed anyway, can also be used at the same time to establish the connection between the piston plug and the driven member. When advancing the output member and / or alone or in part the insertion of the fluid container is thus effected according to the invention a suitable mechanical connection between the piston plug and the output member, which is sufficiently stable for an exact dosage of the fluid dose administered. Examples of such a mechanical connection are a locking, a latching or a snap connection.

When the driven member is pushed axially towards the piston plug, the driven member is preferably not rotated. A simultaneous rotation of the driven member during the axial advancement can, however, in principle be permissible according to the invention in order to produce the connection.

The output member itself or a front end of the output member is preferably pushed into the piston plug to establish the connection and / or the piston plug is pushed over the output member by insertion. In such an embodiment, means for establishing the mechanical connection are provided on the output member, preferably at its front end, for example suitable locking, latching or snap means. These means are received in the piston stopper by correspondingly designed elements, for example by correspondingly designed locking, latching or snap-in means, which can be formed in particular by the threads of conventional piston stopper.

Preferably, the output member can be advanced substantially unimpeded to establish the mechanical connection without exerting any significant driving force on the piston plug. The same preferably applies if the connection is brought about by inserting the fluid container. It is advantageous that no unintentional propelling force is exerted on the piston plug when the mechanical connection is established, which would cause an unintentional release of fluid. For this purpose, the connecting mechanism is designed to be flexible, so that the elements of the connecting mechanism which bring about the mechanical connection are flexible when the driven member is advanced axially and / or are resilient and / or not locked as long as the mechanical connection, for example by locking, latching or snapping, has not yet been established, so that the elements of the connecting mechanism which bring about the mechanical connection, however, after the mechanical connection has been established, prevent it from being adjusted axially lock the output member relative to the piston plug.

It is also advantageous that even with a fluid container that is only half-filled, for example, a connection between the piston plug and the output member can still be reliably established without the piston plug being axially displaced due to an axial force acting on the piston plug when the mechanical connection is established. Especially when the fluid container is only partially filled, there is a risk that due to the mismatched axial positions of the output member and piston plug, the connection of the piston plug will either advance in the direction of advance and thereby release fluid from the fluid container or the piston stopper will be withdrawn counter to the direction of advance and thereby retracted the fluid container is sucked in. In principle, however, this danger also exists in cases in which the fluid container is filled.

In preferred embodiments, the device is provided with a device by means of which the driven member for moving the connection to the piston plug is moved in the direction of advance, preferably by motor. Even more preferably, the device further comprises a device which detects when the driven member and the piston plug are correctly connected to one another and preferably also when the driven member is locked to the piston plug. Such a detection device can in particular comprise a sensor for measuring an axial force or a torque which acts on the output element. The point in time at which the driven member is correctly positioned in the piston plug is signaled by a change in the axial force or the torque measured by the sensor. The change in the measured variable, for example the axial force or the torque, can vary from the wall friction between the piston stopper and the fluid container and / or the flow resistance to the outlet of the The fluid container connecting catheter. The evaluation of the flow resistance requires a catheter. However, this is not a disadvantage since the catheter has to be filled with the fluid after the fluid container has been inserted. It can be used here that the change in the measured variable also increases with the increase in the axial speed which the output element and the piston plug have to produce the connection relative to one another and can thus be detected more easily and reliably.

The connecting mechanism preferably comprises a number of hooks, preferably a number of resilient hooks, which are designed to give way essentially in the radial direction when the driven member is pushed axially onto the piston plug or the axial movement of the fluid container in the direction of the driven member, and then again radially spread to effect the locking against axial displacement of the output member relative to the piston plug by engaging in at least one undercut which is rigidly coupled to the piston plug and is preferably formed in one piece with the piston plug. Since flexible hooks can be produced in a simple and inexpensive manner, a simple and inexpensive connecting mechanism can be created according to the invention.

The undercut is preferably provided in the rear side of the piston plug facing the driven member, preferably in a cavity of the piston plug, and has a suitable profile which is matched to the type of elements producing the mechanical connection and their geometry. In order to facilitate the loosening of the mechanical connection by a relative rotation between the piston plug and the output member, the undercut of the connecting mechanism is preferably designed in the form of a helical thread, with a direction of rotation that corresponds to the direction of rotation in which the mechanical connection is to be released by twisting. The helical thread preferably extends over several revolutions, the thread height being adapted to the shape of the elements that produce the mechanical connection. In order that the mechanical connection can be established simply and reliably, the connection mechanism according to a first embodiment comprises a plurality of hooks which are arranged distributed on the outer circumferential surface and project radially therefrom, the hooks preferably also being arranged distributed along the longitudinal axis of the output member. In this simple way it can be ensured that at least one of the plurality of hooks is always present at a suitable axial position and angular position in order to establish the mechanical connection. The hooks can be grouped into several rings, which are distributed at different positions along the longitudinal axis of the driven member and each comprise a plurality of hooks. In principle, the hooks can also be arranged randomly with respect to their axial position and angular position. The number of hooks is preferably so large that a plurality of the hooks each act as barbs and the plurality of barbs in the connected state press against the direction of advance of the piston plug against one or preferably several undercuts of the piston plug.

According to a preferred embodiment, the output member has a stop against which, when the mechanical connection is established, the back of the piston stopper bears directly. It is advantageous that the piston stopper cannot move in the axial direction during the axial advancement towards the outlet of the fluid container, so that the fluid dose specified by the drive mechanism of the injection or infusion device can be administered precisely.

The aforementioned hooks or the one or more elements producing the mechanical connection are preferably arranged in the axial direction before the output member stops.

The hooks of the connecting mechanism are preferably essentially pivotable or bendable in the radial direction, and preferably without a greater application of force being required for this. In this way it is ensured that when the driven member is axially advanced toward the piston plug or the Insertion movement of the container essentially no driving force is exerted on the plunger stopper, so that no product is released unintentionally.

According to a preferred embodiment, the hooks are designed as elastic elements and made of a suitable material, for example plastic or metal, of suitable strength. Such elastic elements can be easily molded onto the front end of the output member, in particular integrally molded, or attached and make an additional and complex mechanism unnecessary, which would otherwise have to be provided in order to make the elastic elements pivotable or flexible. They are particularly preferably flexible and act as bending beams firmly clamped on one side.

According to a preferred embodiment, the elastic elements of the use mechanism rotate at least slightly when the output member is rotated relative to the piston, i.e. they yield slightly elastically in the circumferential direction, so that the releasing of the connecting mechanism is only countered by a relatively small and thus negligible resistance force.

According to a further embodiment, the hooks of the connecting mechanism are designed as resilient claws which are held at a front end of the output member. The claws are designed so that they can engage in an opposite undercut in order to produce the mechanical connection between the output member and the piston plug. The claws are preferably essentially radially pivotable between a blocking position in which a further pivoting of the claws is blocked and which serves to block the mechanical connection, and a release position in which the claws are pivoted radially back at least to such an extent that the output member in can be pushed towards or into the piston plug essentially without resistance.

The resilient claws are preferably held on guide and fastening elements in such a way that the claws are guided in a straight line against rotation during the pivoting movement and so are prevented from yielding in the circumferential direction. The claws thus do not deflect during their engagement in the undercut by executing a rotary movement, so that the mechanical connection between the piston plug and the output member can be achieved in an even more stable manner.

The connecting mechanism preferably further comprises a resetting means which prestresses the resilient claws against one another and in a radially directed manner. When engaging in the undercut, the resilient claws automatically straighten up again due to the restoring force of the restoring means in order to block the mechanical connection between the piston plug and the output member.

According to a further embodiment, the connection mechanism is designed in such a way that the claws can be adjusted radially in a motor-driven manner, for example with the aid of a spindle drive, in order to establish the mechanical connection between the output member and the piston plug. The moment at which the mechanical connection is established can thus be specified more precisely.

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. Show it:

1 shows a cross section through a connecting mechanism and an infusion pump and a perspective view of the front end of an output member according to a first embodiment of the present invention.

2 shows a cross section through a connection mechanism and an infusion pump and a perspective view of the front end of an output member according to a second embodiment of the present invention;

Fig. 3 shows a cross section through a connecting mechanism and an infusion pump and a perspective view of the front end an output member according to a third embodiment of the present invention;

4 shows two cross-sectional views of an infusion pump and a perspective view of the front end of an output member according to a fourth embodiment of the present invention, just before the connection between the plunger plug and the output member is achieved; and

5 shows two cross-sectional views of the infusion pump according to the fourth embodiment of the present invention after the connection between the plunger stopper and the output member has been established.

In the figures, identical reference symbols designate identical or essentially equivalent elements or groups of elements.

1 shows in the left part a cross section of an infusion pump according to a first embodiment of the present invention. The upper part of FIG. 1 shows in an enlarged cross section the connection mechanism according to this embodiment, the right part finally shows in a perspective view the front end of the output member according to this embodiment.

The infusion pump 1 is used, for example, for the long-term administration of microdoses of a liquid stored in an ampoule 7, which contains a medical or therapeutic active ingredient, preferably insulin. The infusion pump 1 has a housing 2 which is essentially rectangular in cross section, in the interior 3 of which a mechanism and electronics (not shown) for controlling the pump are accommodated. In the right part of the infusion pump 1 there is the essentially cylindrical ampoule 7, which is accommodated in a housing section 8 which corresponds to the ampoule 7. A piston plug 6 is mounted in the ampoule 7 and is axially displaceable. The piston plug 6 is mechanically connected to the piston rod 4, which serves as an output member of the drive device, which is only shown schematically, for axially advancing the piston rod 4 and the piston plug 6. The piston rod 4 is straight in the lower part of the housing 2 and is in threaded engagement with a rotationally driven drive member 5. If the drive member 5 is driven in rotation, preferably by an electric motor, the piston days 4 are displaced axially linearly. In order to dispense the product from the outlet 9 of the ampoule 7, the piston rod 4 pushes the piston stopper 6 towards the outlet 9. The ampoule 7 is mounted exchangeably in the housing section 8. To replace the ampoule 7, the connection between the piston rod 4 and the piston plug 6 must be released. At the same time, with regard to an exact dosing of the product, there is a need for the connection between the piston plug 6 and the piston rod 4 to be blocked against axial displacement or displacement of the piston rod 4 relative to the piston plug 6.

According to the invention, the connection between piston plug 6 and piston rod 4 can be released by relative rotation between piston plug 6 and piston rod 4, and the connection can be established by pushing the piston rod 4 towards or into the piston plug 6. Instead, or in combination with the advancement of the piston rod 4, the connection can be brought about by the opposite movement of the ampoule 7 when it is inserted.

As shown in the right part of FIG. 1, the front end of the piston rod 4 serving as the output member has a number of spring-elastic or at least spring-elastic mounted hooks 13 which jumped in the axial direction before the circumferential stop serving as a stopper for the piston plug 6 are arranged. In the exemplary embodiment, the hooks 13 are formed in the manner of flexible bristles of a brush and protrude obliquely backwards from the piston rod 4 at an acute angle to the axial, so as to form thin elastic bending beams firmly clamped at their front ends. The resilient hooks 13 are combined to form a plurality of rings, in the example shown to a total of five rings, the hooks 13 of a respective ring being arranged approximately at the same axial height and the hooks 13 of the different rings being aligned in the axial direction. Of course, the resilient hook 13 can also be of a different type or disordered be arranged in the manner of a curling brush at the front end of the piston rod 4.

The resilient hooks 13 consist of a resilient material, for example of a plastic or a metal of low strength, so that the hooks 13 when the force is applied radially inwards, for example by contact with the undercut 15, by bending at the base thereof and / or over the whole thereof Giving length essentially in the radial direction and straightening up again after releasing the force.

In the upper part of FIG. 1, which shows the rear end of the ampoule 7 in a greatly enlarged cross section, it is shown how the front end of the piston rod 4 interacts with the piston plug 6. On its rear side, the piston plug 6 has a helical thread 14, the thread 14 in the axial direction in each longitudinal section successively forming a plurality of undercuts 15 on which the resilient hooks 13 lock the axial position of the piston 6 relative to the piston rod 4 Support against the direction of advance. As can be seen from the upper part of FIG. 1, only a part of the resilient hooks 13 is supported in the associated undercut 15 against the direction of advance, while another part of the hooks 13 is not completely erected again, i.e. is not yet spread out radially outward into the relaxed position. When the front end of the piston rod 4 is completely let into the piston plug 6, the rear side of the piston plug 6 lies against the stop 10.

To establish the connection between piston stopper 6 and piston rod 4, the procedure is as follows: The ampoule 7 is delivered in the rear end position shown in the upper part of FIG. 1, in which the rear side of the piston stopper 6 abuts or almost abuts the peripheral projection 10. After removing a used ampoule 7, the piston rod 4 is axially returned to a rear end position. The new ampoule 7 is then inserted into the housing section 8 until finally the front end of the piston rod 4 with the resilient Hook 13 is inserted into the piston plug 6. From the undercuts 15, the resilient hooks 13 are bent radially inward against their elastic restoring force. When the piston rod 4 is pushed further into the cavity open at the rear of the piston plug 6, some of the resilient hooks finally straighten up again depending on the sliding of the tips of the undercuts 15 and engage in an associated undercut 15 arranged at approximately the same height , The connection shown can, as described, be brought about by axially advancing only the piston rod 4 or only by inserting the ampoule 7 or, although less preferred, by a superimposed movement. This should not rule out that a relative rotation between piston plug 6 and piston rod 4 may also be permissible when the piston rod 4 is advanced.

In the position shown in the upper part of FIG. 1, the piston plug 6 and the piston rod 4 cannot be pushed further against one another, since the piston plug 4 abuts the stop 10. Furthermore, the piston plug 6 cannot be advanced axially relative to the piston rod 4 because part of the resilient hook 13 is supported on the piston plug 6 against the direction of advance. Thus, the piston plug 6 is essentially rigidly connected to the piston rod 4.

To release the connection shown, the piston plug 6 must be rotated relative to the piston rod 4, specifically against the course of the screw thread 14, so that the resilient hooks 13 are unscrewed from the thread. For loosening, the hooks 13 form the counter thread for the thread 14 of the piston plug 6, which forms the rear cuts 15.

In principle, the resilient hook 13 need not be distributed around the entire circumference of the front end of the piston rod 4. Rather, the resilient hooks 13 can also be arranged concentrated in special angular ranges, for example at two diametrically opposite positions. In such an alternative embodiment, a relative rotation of 90 degrees would be sufficient to detach the connection, if the connection was rotated by 90 degrees Angular position an axially extending groove or the like is provided, along which the resilient hooks 13 can be withdrawn from engagement with the piston plug 6.

FIG. 2 shows an infusion pump according to a second embodiment of the present invention in a cross section and the front end of the piston rod 4 is shown in a perspective view.

Basically, the second embodiment differs only in that several hook rings 18 are placed on the front end of the piston rod 4. The hook rings 18 each have a circular ring 19, from which the tab-like hooks 13 project radially outward. The hook rings 18 are pushed onto the front end of the piston rod 4, where they each snap into a latching circumferential projection 20. According to the second embodiment, the hooks 13 yield elastically only in the area of the base of the hook, that is to say in the connection area between the hook 13 and the circular ring 19. However, this does not rule out that the hooks 13 are also made of an elastic material, as in the first embodiment. The hook ring 18 is preferably produced by deep drawing a metal.

As in the first embodiment, the connection between the piston plug 6 and the piston rod 4 is produced by axially advancing the front end of the piston rod 4 into the piston plug 6 or by the axial movement of the ampoule 7 immediately upon insertion. No relative rotation is required for this, but this is generally permitted. As in the first embodiment, the connection is released by relative rotation of the piston plug 6 relative to the piston rod 4.

As can be seen from FIGS. 1 and 2, the connection mechanism according to the first and second embodiment comprises a plurality of resilient hooks 13 which are formed at the front end of the piston rod 4. As a rule, these can be produced easily and inexpensively. According to the invention, however, only relatively few resilient hooks can be provided. This is explained below.

3 shows in cross section an infusion pump according to a third embodiment of the present invention and in a perspective view the front end of a piston rod according to this embodiment. As shown in the right part of FIG. 3, four claws 21 are arranged at the front end of the piston rod 4. For this purpose, a central support 22 projects from the front end of the piston rod 4 and a fastening and guiding device 23 with a corresponding number, i.e. around the support 22. in the illustrated embodiment four, from fastening and guide elements. The claws 21 are each pivotally mounted transversely to the axial by means of pins 27 of the fastening and guide device 23. The openings 30 shown are provided for mounting the claws 21. The fastening and guiding device 23 forms four star-shaped gaps 24 in which the claws 21 are guided in a straight line, so that the claws 21 are pivoted essentially only in axial planes around the pivot axes formed by the pins 27 without being able to be rotated in the process , so that the claws 21 do not yield in the circumferential direction when the connection is blocked.

According to the third embodiment, the four claws 21 are arranged in pairs at the same height and the two pairs are axially offset from one another. The claws 21 engage in the connection, like the hooks 13, in the helical thread 14 at different depths. This is shown in the upper part of FIG. 3, where the right claw 21 engages deeper in the undercut 15 than the left claw 21.

As can be seen from the upper part of FIG. 3, two of the claws 21 are prestressed radially outwards with the aid of a compression spring 25 which serves as a restoring means and which can be made of elastic material as an elastomer ring or also of elastic form. The compression spring 25 is held on the carrier 22. The claws 21 thus project maximally radially from the front end of the piston rod in the relieved idle state 4 from. When the front end of the piston rod 4 and the piston plug 6 are inserted one above the other, the claws 21, which slide over the tips of the thread 14, are pivoted radially inwards. When pushed in further, at least one of the claws 21 straightens up again into an opposite undercut 15 due to the restoring force of the compression spring 25 in order to block the connecting mechanism.

As in the other embodiments, the thread 14 does not have to be completely circumferential in the third embodiment either. Rather, it is sufficient, but not preferred, if the thread 14 is formed only at sections where it lies opposite the claws 21 and is otherwise replaced by axially extending grooves or the like. Such grooves can be offset by 45 degrees relative to the claws 21 in the connecting position, so that the connection can be released again by simply turning the piston plug 6 and the piston rod 4 by 45 degrees. However, the thread 14 preferably runs continuously. It is also particularly advantageous that the piston plug 6 with thread 14 can be a conventional piston plug, in particular with a thread 14 that is customary for this, i.e. the invention does not require any adjustment on the side of the piston plug, which applies to all other exemplary embodiments.

According to a fourth embodiment, which is shown in FIGS. 4 and 5, the pivotable claws 21 are forcibly pivoted without the action of the undercuts 15 in order to establish the mechanical connection between the piston plug 6 and the output member 4.

In the fourth embodiment, the piston rod 4 is formed in two parts and comprises a centrally arranged slide rod 4a and a threaded sleeve 4b, which surrounds the slide rod 4a and guides axially linear. The threaded sleeve 4b has an external thread over almost its entire axial length, which is interrupted by a straight guide over its axial length. The threaded sleeve 4b is in threaded engagement with its external thread with an internal thread of the drive member 5. The drive member 5 is driven by a motor, not shown. The threaded sleeve 4b is guided axially in a straight line by the housing 2. A drive rotation of the drive member 5 therefore causes the threaded sleeve 4b to advance. As already mentioned, the slide rod 4a is accommodated in the threaded sleeve 4b in an axially slidable manner. Movement relative to the threaded sleeve 4b against the direction of advance is limited by a stop shoulder 31 which is formed at the front end of the slide rod 4a and with which the slide rod 4a is supported at the front end of the threaded sleeve 4b.

In the position shown in FIG. 4, which the piston rod 4 emits when a full ampoule 7 is inserted, the slide rod 4a is also axially supported on the housing 8 with its rear end. The slide rod 4a projects with a head piece 33 and the stop shoulder 31 axially beyond the stop 10 of the threaded sleeve 4b and into the fastening and guide device 23 formed by the threaded sleeve 4b and which pivotally supports a plurality of claws 21. The guiding and fastening device 23 and the claws 21 are formed essentially like those of the third exemplary embodiment. In the fourth exemplary embodiment, the pins 27 again form the pivot axis for each of the claws 21. From the pin 27, each of the claws 21 forms an outer leg 26 and an inner leg 28. The claws 21 are each approximately L-shaped, the respective pivot axis being arranged in the region of the intersection of the two legs 26 and 28 of the L-shape. A compression spring 32 is arranged between the cover 29, which is comparable to the cover of the third exemplary embodiment, and the respective inner leg 26 of each claw 21, ie one compression spring 32 per claw 21. The elastic spring forces of the compression springs 32 cause the claws 21 Spread radially outward about the pivot axes of the pins 27. Conversely, this means that in order to insert the slide rod 4a into the cavity of the piston plug 6, the compression springs 32 are forcibly compressed and the outer legs 26 are thereby pivoted radially inwards. Figure 4 shows the device in the state in which the legs 26 of the claws 21 are pivoted radially inward against the force of the respective compression spring 32. For this application of the claws 21, the slide rod 4a takes up its foremost axial position relative to the threaded sleeve 4b, in which the stop shoulder 31 is axially spaced a little from the front end of the threaded sleeve 4b. The head piece 33 presses like a plunger in the direction of advance against the inner legs 28 of the claws 21, so that the claws 21 are pivoted radially inward with their outer legs 26. The threaded sleeve 4b is axially supported on the housing 8 with its stop 10 against the direction of advance. In this state of the piston rod 4, the ampoule 7 is pushed into the housing 8 against the direction of advance until the piston stopper 6 seated at the rear end of the ampoule 7 is pushed onto the guide and fastening device 23. Sliding on is not impeded by the swung-in claws 26. After completion of this first phase of establishing the connection, the device is in the state shown in FIG. 4, in which the piston plug 6 is in stop contact with the stop 10 of the threaded sleeve 4b and / or the guide and fastening element 23 and the slide rod 4a against the direction of advance takes its axially foremost position relative to the threaded sleeve 4 b, in which its stop shoulder 31 is axially clear from the front end of the stop 10.

In order to produce the connection between the piston rod 4 and the piston plug 6 from the state shown in FIG. 4, the drive member 5 is driven in rotation, so that the threaded sleeve 4b translates in the direction of advance due to its straight guidance. During this forward movement, its stop 10 lifts off the counter-abutment surface of the housing section 8 and the piston plug 6 seated on the stop 10 is moved together with the threaded sleeve 4b in the direction of advance. The tensioned compression springs 32 press the slide rod 4a over the claws 21 against the direction of advance. Since the slide rod 4a is blocked against axial movement against the direction of advance, in the exemplary embodiment by being supported on the housing 8 at its rear end, the compression springs 32 press with their elastic restoring forces onto the inner legs 28 of the claws 21, so that pivot the outer legs 26 radially outward about the pins 27. The pivoting process is ended when the claws 21 come to a stop to the rear surfaces of the undercuts 15 or the stop 10 comes into contact with the stop shoulder 31.

Figure 5 shows the device in the state in which the connection between the piston rod 4 and the piston 6 is made. At least one of the four claws 21 is in abutment against a surface of the undercut 15 facing in the direction of advance, so that the piston rod 4 and the piston plug 6 are axially fixed to one another. In the fourth exemplary embodiment, the pivot axes of all the claws 21, in the exemplary embodiment four claws 21, are arranged axially at the same height. The undercuts 15, as in the other exemplary embodiments, are preferably formed by a thread which runs continuously in several revolutions.

In order to be able to move the slide rod 4a in other axial positions of the piston rod 4 relative to the threaded sleeve 4b in the advancing direction, it is preferred if an adjusting device acts between the slide rod 4a and the threaded sleeve 4b. The adjusting device can be implemented, for example, by a magnetic coupling of the slide rod 4a and the threaded sleeve 4b by means of electromagnets. A purely mechanical adjusting device is also conceivable.

Although the connection mechanism has been described above in connection with a motor-driven infusion pump, the invention is not restricted to this. Rather, the connection mechanism can also be applied to injection devices in which the ampoule containing the product is to be exchanged.

When using such injection or infusion devices for diabetes treatment by administering insulin, it has proven particularly advantageous Use of Gauge 30 or Gauge 31 hollow needles, which are attached to the outlet of the fluid container.

LIST OF REFERENCE NUMBERS

1 infusion pump housing

3 housing interior for drive mechanism etc. output link, piston rod

4a slide rod

4b threaded sleeve

5 drive link

6 piston plugs

7 containers / ampoule

8 housing section

9 outlet

10 stop

11 Wall of the container / ampoule

12 -

13 hooks

14 thread / thread

15 undercut

16 -

17 -

18 hook ring

19 circular ring

20 -

21 claw

22 carriers

23 Fastening and guiding device gap

compression spring

claw

Pin inner swivel arm

cover

opening

stop shoulder

compression spring

headpiece

Claims

claims

1. Device for the preferably metered administration of a liquid product, comprising a container (7) for storing the product, a piston stopper (6) which can be axially displaced in an advancing direction from an output member (4) to an outlet (9) of the container to effect a distribution of product from the container (7) and a connecting mechanism for releasably connecting the piston plug (6) to the output member (4), the connecting mechanism connecting the piston plug (6) and the output member (4) against one another axially adjusting the driven member and the piston plug (6) blocks relative to each other and the connection can be released by a relative rotation between the piston plug (6) and the driven member (4), characterized in that the connecting mechanism is designed so that the connection between the piston plug (6) and the output member (4) by axially, linearly adjusting the output member (4) and the Piston plug (6) can be produced relative to one another.

2. The device according to claim 1, wherein the connecting mechanism comprises a number of hook elements (13; 21), which are designed to give in the axial adjustment substantially in the radial direction and to straighten up again, by engagement in at least one undercut (15 ), which is rigidly coupled to the piston plug (6), to effect the blocking against the axial displacement of the output member (4) relative to the piston plug (6).

3. Apparatus according to claim 2, wherein the undercut (15) of the connecting mechanism is formed in the form of a helical thread (14).

4. The device according to claim 2 or 3, wherein the output member (4) has a stop (10) for the piston plug (6) and the hook elements (13; 21) in the axial Arranged in front of the stop (10), and that the hook elements (13; 21) support the piston plug (6) against the direction of advance after it has been erected.

5. Device according to one of claims 2 to 4, wherein the hook elements (13; 21) of the connecting mechanism against elastic restoring forces are pivotable or bendable.

6. Device according to one of claims 2 to 5, wherein the hook elements (13) of the connecting mechanism are formed by a number of elastic elements which protrude radially from a front end of the output member (4).

7. Device according to one of claims 2 to 6, wherein the hook elements (13) give in the circumferential direction relative to the piston stopper (6) during the relative rotation of the driven member (4).

8. Device according to one of claims 2 to 5, wherein the hook elements of the connecting mechanism are designed as resilient claws (21) which are held at a front end of the output member (4) and are substantially radially pivotable.

9. Device according to one of claims 2 to 8, wherein the hook elements (21) are held on a guide and fastening element (23) at the front end of the output device so that the hook elements (21) are guided against rotation during the pivoting movement ,

10. The device according to one of claims 2 to 9, wherein the connecting mechanism further comprises a reset means (25; 32) which biases the hook elements (21) radially spread (15; 32).

11. The device according to one of claims 2 to 10, wherein a restoring means (32) in each case on one of the in the undercut (15) engaging end of one of the Hook elements (21) opposite end (28) of the hook element (21) acts to radially bias the hook element (21).

12. The device according to one of claims 2 to 11, wherein the hook elements are radially adjustable by motor in order to establish and release the mechanical connection between the piston plug and the output member.

13. The device according to one of claims 2 to 12, wherein the connecting mechanism is designed such that the hook elements (13; 21) on the output member (4) and the undercut (15) are arranged on a rear side of the piston plug (6).

14. Device according to one of claims 2 to 12, wherein the connecting mechanism is designed such that the hook elements are arranged on a rear side of the piston plug and the undercut on the output member.

15. Device according to one of the preceding claims, in which a Gauge 30 or Gauge 31 hollow needle for dispensing the product is attached to the outlet (9).