CONVEYING DEVICE FOR AN APPARATUS FOR ADMINISTERING A DRUG

The invention relates to a conveying device in or for an apparatus for administering a product. The apparatus can in particular be an infusion apparatus or injection apparatus for administering a drug, a diagnostic agent or in principle any other product which can be administered to a human or animal subject. One preferred application of the invention is the self-administering of drugs, in particular administering insulin in the treatment of diabetes,

In many cases, infusion apparatus and injection apparatus for administering the product in exact doses employ a threaded drive in order to convert a torque of a drive motor into an axial translational movement of a conveying member in the threaded engagement and to deliver the product from a reservoir of the infusion apparatus or injection apparatus by the axial movement. Once the reservoir has been emptied, the conveying member has to be rotated back in the threaded engagement into an initial position in order to be used again, which can either be laboriously performed manually or requires a direction-reversible drive motor which consumes energy for the reverse rotation.

WO 2005/094921 Al proposes a threaded drive comprising two conveying members in a threaded engagement, one of which is slit in the region of its thread and is therefore radially flexible. The relevant conveying member can therefore be axially pushed into threaded engagement with the other conveying member, up to and against a stopper, without a rotational movement. In order to be able to establish the threaded engagement in the stopper position despite the radial flexibility, however, the conveying member which is flexible in the region of its thread has to be rotated about the threaded axis in the stopper position. Establishing the threaded engagement requires a particular hand operation and therefore particular concentration and dexterity at the end of axial insertion.. This is in particular problematic for applications in which the user administers the product himself, such as for example in the treatment of diabetes.

WO 2005/094921 Al also desciibes a modified mechanism in which the thieaded engagement is automatically established when the conveying member is pushed in In the modification, a flexible thread iegion is cieated by means ol segments which pioject radially with iespect to the threaded axis, can be elastically bent and aie theiefoie correspondingly slendei, and which togethei foim the thiead of the conveying member. When the conveying niembci is pushed in, the bendable segments slide elastically over the thiead of the othei conveying membei In the thieaded engagement, the segments foiming the flexible thread theiefoie always press, with theii spiing force which is based on bending elasticity, into the turns of the thiead ol the other conveying membei A coπesponding amount of eneigy is needed foi the diive

It is an object of the invention to provide a conveying device of the type cited, comprising conveying membeis which can easily be moved into a fiee-moving thieaded engagement with each othei by means ol an axial movement to be pei formed lelative to each othei.

The subject of the invention is a conveying device in or foi an apparatus for administering a pioduct which can be administered to a human or animal subject, which comprises a base, a fnst conveying member which can be moved relative to the base, and a second conveying member which can be moved lelative to the base The fiist conveying member is provided with a fiist thiead and the second conveying member is provided with a second thiead The thieads aie in a threaded engagement with each othei when the pioduct is being administered, such that the conveying membei s together foim a threaded diive. The second thiead extends over an axial portion of the second conveying membei which is iadially flexible in ielation to its thieaded axis, such that one of the conveying members can be axially pushed into the other in an overlap ol the thieads, and a lelative rotational movement between the conveying members is not lequiied in ordei to establish the axial oveilap. The base forms a fiame foi the fiist and second conveying membei. The base can comprise a casing ol the administering apparatus, in which other components of the administeiing apparatus - for example, a resei voii for the pioduct - are accommodated The base can also, howevei, be an attached part oi piefeiably an installed pait which is airanged on oi pieferably in such a casing ol the administeiing apparatus or is provided foi such an aπangement

In accordance with the invention, the conveying device compiises, in addition to the components cited, a blocking menibei which can be moved relative to the second conveying member or relative to which the second conveying membei can be moved into a blocking position in which the blocking member holds the second thread in the thieaded engagement with the thiead of the first conveying membei by radially stiffening the flexible axial portion. In the blocking position, the blocking membei pievents the second thiead from being able to be moved out of the thieaded engagement by an axial load, due to the flexibility of the axial portion. Because the flexible axial portion and theiefoie the second thread is stiffened by means of a blocking member which is additionally piovided, it is possible to establish the thieaded engagement of the conveying members in a simple way and at least essentially without relative iotation It is also not necessary to foim any filigree bending tongues which necessaiily clamp in the threaded engagement, since a restoring elasticity foice of the conveying member does not have to ensure the thieaded engagement, but rather the additional blocking member serves to stiffen the iadially flexible thread. Depending on the geometry of the second conveying member in the region of the second thread, the blocking member in the blocking position can also press the second thiead into the thieaded engagement with a small iadial piessing force, wheiein the pressing force pieferably exists only between the blocking member and the second conveying member and not between the two threads The blocking membei and the second conveying member can have a point contact, line contact or area contact, wheiein the points, lines oi areas which contact each othei aic offset with iespect to each othei in the circumfeiential diiection about the threaded axis at least substantially by 180°.

Foi establishing the threaded engagement, the blocking member is pieferably moved into the blocking position not only relative to the second conveying membei but also simultaneously lelative to the base and the fust conveying membei. Foi an alternative embodiment, howevei, it is also conceivable foi the blocking member to assume the blocking position even before the thieaded engagement is established, and to entei an engagement with the second conveying member in the final moment of the lelative insertion movement between the conveying membei s, in which it stiffens its flexible axial portion at least in the iegion of the second thiead, in order to secure the second tluead against flexing under a load in the thieaded engagement with the first thtead. In such an alternative embodiment, the engagement is also configuied such that during its conveying movement, the second conveying membei slaves the blocking membei

relative to the first conveying menibei. To this end, the blocking membci and the second conveying membei can foi example hook togethei The second conveying member collects the blocking menibei from the blocking position, so to speak, so that the blocking member provides for the stiffening in the region of the thicad dining administeiing. As a result, the blocking member can thus be moved at least relative to the second conveying member into the blocking position, which also includes the case in which it is not the blocking membei but rather the second conveying membei which is moved relative to the fust conveying membei and prefeiably also lelative to the base, until the engagement with the blocking member which stiffens the thread is established, Foi stiffening the second thread, at least the blocking member and the second conveying membei ate moved lelative to each othei into the blocking position In the piefened fust valiant, the blocking member is moved lelative to the second conveying member and also relative to the first conveying member and the base foi this pin pose In the second valiant, the blocking membei is moved relative to the fust conveying member and the base, at least while the pioduct is being administeied The blocking member can thus be moved relative to the first conveying membei and the base In order to be able to fulfil the stiffening function, the blocking member is fotmed so as to confoim to the flexible axial poition of the second conveying member or at least to said axial portion in the region of the thiead

In piefened embodiments, the blocking member can be moved lelative to the second conveying member, oi the second conveying membei can be moved relative to the blocking member, in the axial diiection, i.e. along the thieaded axis, preferably centrically with respect to the second thiead on the threaded axis, into the blocking position, The blocking membei advantageously pei forms the movement into the blocking position both lelative to the second conveying membei and lelative to the fust conveying member and prefeiably also lelative to the base. The blocking membei and the second conveying membei arc piefeiably moved in the same axial direction relative to the Fust conveying membei, the second conveying member into the axial oveilap of the threads, and the blocking membei into the blocking position.

In its conveying movement as pei formed lelative Io the first conveying member in the couise oi administeiing the pioduct, the second conveying membei piefeiably slaves the blocking member, such that the blocking membei always piovides foi the stiffening in the iegion of the second thiead The second conveying member piefeiably mounts the blocking member directly

In prefeired embodiments, the blocking member in the blocking position is axially fixed relative to the second conveying member. The fixation can in principle be a non-positive fit, including a purely non-positive fit, but is preferably a positive fit or at least comprises a positive-fit engagement. The fixation can in particular be formed by means of a locking engagement which pieferably exists directly between the blocking member and the second conveying member.

In one development, the blocking member can be moved out of a releasable fixing engagement - which can be formed as a purely non-positive fit or a purely positive fit or a positive and non- positive fit, preferably a locking engagement - relative to the second conveying member, out of an initial position into the blocking position, The fixing engagement which holds the blocking membei in the initial position can in particular exist directly between the blocking member and the second conveying member.

The second conveying member and the blocking member can advantageously form a piston rod together, if the administering appaiatus conveys the product by means of a piston which can be axially moved in the leservoir, In such embodiments, it is also advantageous if the blocking member forms a fiont end of the piston rod which is connected to the piston or preferably meiely faces the piston-

In preferred embodiments, the blocking member and the second conveying member together form a telescope. Preferably, the telescope is retracted, Le. its axial length is reduced, for stiffening the second thread. Preferably, the blocking membei protrudes into the second conveying member; however, these conditions can in principle be reveised, depending on whether the second thread is embodied as an inner thread or preferably as an outer thread.

The axial flexibility of the axial portion provided with the second thread can in particular be obtained in the relevant axial portion by means of one oi more axially extending breach(es) in the second conveying membei. The breaches advantageously extend up to an axial end of the second conveying member, such that the flexible axial portion of the second conveying membei comprises a number of axially extending arms which converge, away fiom the relevant axial end, preferably in a conjoining poition of the second conveying member. At least one of the arms, piefeiably a numbei of the arms and preferably all of the arms adopt the thread function

together, by each aim forming an arc segment ol the thiead on a circumferential surface. It would in principle also be sufficient foi the second conveying membei to comprise only one arm which is iadially flexible and forms a thieaded segment. More pieferably, the second conveying membei compiises a numbei of aims, foi example foui aims, which are foi example obtained by a cioss-shaped slit in the second conveying membei, in a view onto the tear end of said conveying member In particuϊaily piefeπed embodiments, the flexible axial portion of the second conveying membei comprises exactly two arms which are obtained by a single, axially extending slit. The aims aie axially extending bending aims, i.e. they can. be bent radially inwaids oi pieferably radially outwards from the respective axial fastening end, into the thieaded engagement, such that the ciicumfeiential surface of the lcspective aim which is provided with the respective threaded segment points tiansverse to the diiection in which said thieaded segment is moved into the threaded engagement.

Although it would be sufficient foi the second thiead to only comprise a single turn or to even only extend ovei an angle of less than 360° about the thieaded axis, it is howevei preferable for the second thiead to comprise rnoie than one complete turn, prefeiably a number of complete turns of the thread On the other hand, it advantageously comprises significantly fewer turns of the thread than the first thread, i e in piefened embodiments, it is significantly shoiter axially than the first thread. The fust thiead thus prefeiably comprises several times mote turns than the second thread

The second thread, more specifically its ciicumfeiential covering suiface, is prefeiably cylindrical in its stiffened state, when the flexible axial portion of the second conveying member abuts the blocking membei in the region of the second thread This also contributes to a free- moving, smooth threaded engagement In a preferred variant, this also corresponds to the unloaded state of the flexible axial portion In other variants, howevei, the flexible axial portion can also foi example be inclined linearly oi in a cuive with respect to the threaded axis. Howevei, it is also advantageously the case with these othei variants that the circumferential covering surface of the second thread is cylindrical when the blocking member is in the blocking position, i c it is moved into the cylindrical shape by means of the blocking membei.

In preferred embodiments, the second conveying member and the blocking member are designed to be used once only, and aie exchanged for a new second conveying member and a new blocking member when the reservoir is exchanged or refilled. By contrast, the first conveying member and the base are preferably used repeatedly. In such a design, it may be advantageous for the second conveying member to be formed from a softer material than the first conveying member, or at least for' the second thread to be formed using a softer material than the first thread, In preferred embodiments, the conveying members and the blocking member ¹ are each formed in one piece, for example formed from plastic by injection moulding. One of the conveying members or both conveying members or the blocking member can however in principle also consist of a number of separately formed parts which are respectively connected to each other such that they respectively perform the movements required for establishing the threaded engagement and when conveying the product as a unit.

Advantageous features are also described in the sub-claims and combinations of them.

An example embodiment of the invention is illustrated below on the basis of figures. Features disclosed by the example embodiment, each individually and in any combination, advantageously develop the subjects of the claims and also the embodiments described above. There is shown:

Figure 1 a conveying device in an initial state, before a threaded drive comprising two conveying members is assembled; Figure 2 the conveying device, after assembly;

Figure 3 the conveying device in its initial state, in a longitudinal section;

Figure 4 the conveying device in its initial state, in a partial view and a partial longitudinal section;

Figure 5 one of the conveying members in a longitudinal section; and

Figure 6 a blocking member of the conveying device, in a longitudinal section,

Figure 1 shows a conveying device of an apparatus foi administering a fluid product. In the example embodiment, the apparatus is formed by an infusion pump for subcutaneously administering a fluid drug, for example insulin, which can be worn on the body, on or

underneath one's clothing. The conveying device shown in Figure 1 can in particular be arranged in a casing of such an apparatus. It serves to convey the product contained in a reservoir. A piston is movably arranged in the reservoir. In order to be administered, the product is conveyed by advancing the piston in an axial direction towards an outlet of the reservoir. The conveying device serves to advance such a piston.

The conveying device comprises bearing structures 1 and 2 which together form a base 1, 2 for mounting and supporting other components of the conveying device. The conveying device also comprises a motorised drive 3, a first conveying member 4, a second conveying member 5 and a blocking member 6. The first conveying member 4 can be rotated about a rotational axis R relative to the base 1, 2, and is axially fixed, The axial fixation relative to the base 1 , 2 can be absolute, within production tolerances. In one variant, smaller axial stroke movements along the rotational axis R can also be possible, in order for example to measure an axial force which acts on the conveying member 4 when the product is being conveyed. The second conveying member 5 is shown in Figure 1 detached from the first conveying member 4, before the conveying device is assembled.

Figure 2 shows the conveying device in its assembled state. The second conveying member 5 protrudes into the first conveying membei 4. In the assembled state, the conveying members 4 and 5 are in threaded engagement with each other, the threaded axis of which is the rotational axis R which is therefore referred to in the following as the threaded axis R. The drive 3 is coupled to the first conveying member 4 in the region of the bearing structure 2 by means of a gear. The gear can in particular be a toothed wheel gear. The drive 3 is a rotary motor, for example an electric step motor, having a motor axis which is parallel to the threaded axis R, The gear can accordingly be a simple spur wheel gear. The first conveying member 4 is connected non-rotationally to a gear wheel, which also includes the case in which such a gear wheel can be formed in one piece with the conveying member 4.

The second conveying member 5 and the blocking member 6 together form a piston rod which is axially moved relative to the base 1, 2 and the conveying member 4 when the conveying member 4 is rotary-driven while the conveying members 4 and 5 are in threaded engagement. In an axial movement in an advancing direction V, the piston rod 5, 6 presses against the piston, such that

the piston is likewise moved in the advancing direction V towards the outlet of the reservoir and product is deliveied in accordance with the advancing movement. At its front end in the advancing diiection V, the blocking member 6 compπses a plunger 7 with which it pi esses against the piston in the advancing diiection V and thus advances the piston. There is pressing contact between the piston rod 5, 6 and the piston only in the advancing direction V, There is no connection in the opposite direction, such that the piston rod 5, 6 can easily be detached from the piston by a movement relative to the piston and counter to the advancing direction V.

Figure 3 shows a longitudinal section of the conveying device, in a sectional plane which is at right angles to the plane of view in Figuie 1. The threaded axis R extends in the sectional plane. Figure 4 shows the conveying device in a sectional plane of view which is offset in parallel with iespect to the sectional plane in Figuie 3 and extends through the conveying membei 4 at a distance from the piston rod 5, 6 In Figuies 3 and 4, as in Figure I, the conveying device is not yet in its assembled state.

Staiting from the initial state shown in Figure 3, the piston rod 5, 6 - i.e. the combination of the conveying member 5 and the blocking member 6 - can be axially inserted into the conveying membei 4, counter to the advancing direction V, up to an axial stopper position. The stopper position shown in Figure 2 is detei mined by a stopper contact between the conveying member 5 and a stopper which in the example embodiment is formed by the conveying membei 4, but which in modifications could also for example be formed by the base I , 2, for example by the beaiing stiucture 2.

The conveying member 4 is a sleeve structure comprising a sleeve poition and a bottom at an axially rear end. The sleeve portion extends over almost the entire axial length of the conveying member 4. A first thread 8 is formed on an inner surface area of the sleeve portion. The thiead 8 extends over the entire length of the sleeve poilion of the conveying member 4. The conveying member 4 could also be formed without the bottom, as an axially continuous sleeve. In such modifications, the thiead 8 could axially extend continuously ovei the entire length of the conveying member 4.

At its reai end, the conveying member 5 comprises a second thread 9 on its outer circumference, which is formed, as an outer thread, so as to conform to the first thread 8, for the threaded engagement with the first thread 8. The thread 9 only extends over a smaller part of the axial length of the thread 8, but nonetheless comprises a number of turns of the thread, in order to ensure a non-clamping and therefore free-moving but still fixed threaded engagement. The conveying member 5 is substantially likewise sleeve-shaped and, in a front region, comprises a sleeve portion which is self-containing in the circumferential direction about the threaded axis R, and arms 11 and 12 which axially project backwards from the sleeve portion, counter to the advancing direction V, and on which the thread 9 is formed. The arms 1 1 and 12 each form an arc segment of the thread 9 on their outer circumference. Each of the arc segments extends over an angle of less than 180° in the circumferential direction about the threaded axis R. The thread 9 extends up to the axial rear end on each of the arms 1 1 and 12, The arms 31 and 12 are separated from each other on both their sides, each by a breach 13 which extends at the front end of the conveying member 5 continuously from the sleeve portion to the rear end of the conveying member 5. The arms 11 and 12 can be elastically bent towards each other, into the breaches 13, as long as the space between the arms 1 1 and 12 is free, In its shape, the conveying member 5 corresponds to a cylindrical sleeve which is continuously slit from its rear end to the front sleeve portion, such that the breaches 13 each have the shape of linear axial slits. The arms 1 1 and 12 form a flexible axial portion of the conveying member 5 and a radially flexible thread 9,

In the initial state of the conveying device shown in Figures 1, 3 and 4, the blocking member 6 assumes an axial initial position relative to the conveying member 5. In the initial position, only its axially rear end portion protrudes into the front sleeve portion of the conveying member 5, In the initial position, the blocking member 6 is releasably fixed in the axial direction relative to the conveying member 5. In the example embodiment, the fixing engagement is formed directly between the conveying member 5 and the blocking member 6, as a locking engagement, A first locking means 14 of the conveying member 5 and a first locking counter means 16 of the blocking member 6 are locked to each other in the locking engagement. The blocking member 6 can only be moved out of this fixing engagement against a restoring elasticity force, counter to the advancing direction V; a relative movement in the advancing direction V is prevented by the fixing engagement. The locking means 14 is formed on an inner surface area of the conveying member 5, in the form of recesses. Two such locking means 14 are formed in the example

embodiment, offset with respect to each other by 180° in the circumferential direction. The locking counter means 16 is correspondingly formed on the outer circumference of the blocking member 6 as radially projecting locking cams. In the example embodiment, locking counter means 16 which are arranged on the blocking member 6 are formed in accordance with the number of locking means 14 and so as to conform. Instead of forming each of the locking means 14 as a recess and each of the locking counter means 16 as a bump or cam, the locking means 14 could also be formed as bumps or cams and the locking counter means 16 as recesses; hybrid forms are equally conceivable. The locking means 14 and locking counter means 16 could also each consist of only a single locking means 14 and correspondingly a single locking counter means 16; however, a uniform distribution of a number of locking means 14 and locking counter means 16 in the circumferential direction about the threaded axis R is preferred.

In the initial position, the blocking member 6 axially protrudes only far enough into the conveying member 5 that it does not obstruct the bending movement of the arms 1 1 and 12 towards each other, oi at least does not prevent the movement of the arc segments of the thread 9 towards each other. The blocking member 6 can be axially moved relative to the conveying member 5, counter to the advancing direction V, from the initial position into a blocking position in which it protrudes into the space between the arc segments of the thread 9 which in the initial position was still free, and radially fills said space between the arc segments of the thread 9. When the blocking member 6 assumes the blocking position relative to the conveying member 5, the arc segments of the thread 9 can therefore no longer be moved towards each other, transverse to an imaginary circumferential covering surface of the thread 9, such that the axial portion which is still flexible in the initial position of the blocking member 6 and comprises the thread 9 is stiffened, and forms a rigid threaded portion with the blocking member 6 which is in the blocking position.

In the blocking position, the blocking member 6 is axially fixed relative to the conveying member 5. This other fixing engagement is also formed directly between the conveying member 5 and the blocking member 6. It is automatically set when the blocking member 6 is pressed out of the initial position into the blocking position, deeper into the conveying member 5. This second fixing engagement is likewise formed as a locking engagement, namely between a second locking means 15 of the conveying member 5 and the first locking counter means 16 of

the blocking member 6. In accordance with whether the locking counter means 16 is formed as one or more cams, the second locking means 15 is also formed as one or more recess(es) - in the example embodiment, with one recess on an inner surface area of each of the arms 1 1 and 12, respectively. In order to fortify the fixing engagement in the blocking position of the blocking member 6, the blocking member 6 is also provided with a second locking counter means 17 which, in the blocking position, enters a fixing engagement - in the example embodiment, a locking engagement - with the first locking means 14 of the conveying member 5, That which has been said with respect to the locking means 14 and the locking counter means 16 for the fixing engagement in the initial position also applies equally to the second locking means 15 and the second locking counter means 17 and the respective fixing engagement in the blocking position of the blocking member 6,

Figures 5 and 6, which respectively show the conveying member 5 and the blocking member 6 individually and in the same section as Figure 3, show the locking means and locking counter means 14 to 17 more clearly than in Figure 3.

The blocking member 6 is connected to the conveying member 5 such that it can be axially moved but is secured against rotating in relation to the threaded axis R. The conveying member 5 forms an axial guiding path for the blocking member 6. The conveying member 5 can be axialiy moved relative to the base 1, 2 along the threaded axis R and is pi evented from rotating about the threaded axis R by a corresponding guiding engagement, for example a guiding engagement of the base 1, 2. When the threads 8 and 9 are in engagement, the conveying member 5 and together with it the blocking member 6 is therefore axially moved in the advancing direction V when the conveying member 4 is rotary-driven, and likewise advances the piston in the reservoir in the advancing diiection V during its axial movement, in order to deliver product, When the reservoir has been emptied, the conveying member 5 protrudes far enough out of the conveying member 4 that only the threads 8 and 9 still axially overlap with each other.

Once the reservoir has been emptied, the conveying member 5 can be moved completely out of the threaded engagement quickly and with little input of energy, by means of the drive 3 and the conveying niembei 4, by rotating the conveying member 4 further by a few rotations, the number of which corresponds to the number of turns of the thread 9. The conveying member 5 and the

blocking member 6 can be exchanged for a new conveying member 5 and a new blocking member 6, if they are designed as disposable parts, oi as applicable are used again, to which end however the fixation of the blocking member 6 in the blocking position has to be configured to be releasable.

If, as preferred, the conveying member 5 and the blocking member 6 are exchanged, then once the old piston rod 5, 6 has been expelled, the user grips the new combination of the conveying member 5 and blocking membei 6, with the new blocking member 6 fixed to the conveying member 5 in the initial position, and axially inserts the conveying member 5 into the conveying member 4, counter to the advancing direction V. The insertion movement can be easily performed due to the elastically bending arms 1 1 and 12. The user merely has to press the combination of the conveying membei 5 and blocking member 6 like a plunger into the conveying member 4, up to the stopper position, with a slight pressure. During this axial movement, the thread 9 elastically slides off on the thread 8, with a slight radial pressure, in accordance with its restoring bending elasticity, As soon as the conveying member 5 has reached the stopper position, the user presses the blocking member 6 counter to the advancing direction V, axially deeper into the conveying member 5, until it locks to the conveying member 5 in the blocking position. Reaching the blocking position is tactilely perceived, and preferably additionally detected by means of a sensor of the conveying device. The correct positioning of the blocking member 6 is preferably also indicated to the user, preferably optically by means of a display of the apparatus. When the blocking membei 6 assumes the blocking position and the arc segments of the thread 9 can therefore no longer be bent inwards out of the threaded engagement with the thread 8, a fixed and axially non-slip but still free-moving threaded engagement is ensured, such that the device is ready for delivering the product from a reservoir which has been refilled or from a new reservoir which, including its contents and piston, has been exchanged.

Reference signs:

1 base, bearing structure

2 base, bearing structure

3 diive

4 fust conveying member

5 second conveying member

6 blocking member

7 plunger

8 first thread

9 second thiead

30 -

11 aim

12 aim

13 breach

14 first locking means

15 second locking means

16 first locking countei means

17 second locking countei means

R thieaded axis

V advancing direction