WO2012031627A1

WO2012031627A1 - Telescopic piston rod for partially filled syringes

Info

Publication number: WO2012031627A1
Application number: PCT/EP2010/063239
Authority: WO
Inventors: Ursina Streit; Ulrich Moser; Patrick Vogt
Original assignee: Tecpharma Licensing Ag
Priority date: 2010-09-09
Filing date: 2010-09-09
Publication date: 2012-03-15

Abstract

The invention relates to a device for automatically administering a product, comprising a piston 3 which can be shifted out of an initial position in a delivery direction by a delivery stroke S_d. The device also comprises: a multiple-part piston rod which comprises a first part 52 and a second part 53 which engages with the first part 52 by means of an engaging member 53a, hence the first part 52 and the second part 53 are connected axially fixed; and a securing means 60 which holds the engaging member 53a in its engagement with the first part 52; wherein the first and second parts 52; 53 which are connected axially fixed can be shifted by the delivery stroke S_d and relative to the securing means 60, and the engaging member 53a can be shifted beyond the reach of the securing means 60 by means of the delivery stroke S_d, thus enabling the engaging member 53a to be released from its engagement with the first part 52, such the first part 52 can be moved in the delivery direction, in particular by an idle stroke S_i, relative to the second part 53.

Description

Telescopic Piston Rod for Partially Filled Syringes

The invention relates to a device for administering a liquid product, in particular a drug. Such an administering device can in particular be a so-called auto-injector which is configured such that at least a product delivery and preferably also the insertion of a needle can be performed automatically.

An injection device which is configured as an auto-injector is known from German patent application No. 10 2007 013 838, wherein a needle is automatically inserted, the product is then automatically delivered and once the product has been delivered, the needle is automatically retracted into the housing. The injection device disclosed in said German patent application, and/or its inserting, delivering and retracting mechanism, preferably forms a starting point or platform for the present invention. Said German patent application includes a completely filled syringe which comprises a syringe piston which is arranged at a small axial distance from the distal end of a piston rod. When the device's delivery sequence is triggered, the piston rod performs an idle stroke corresponding to this distance and then hits the piston, in order to slave it for the product delivery. Since the distance and therefore the idle stroke are very small, the advancing spring can only accelerate the piston rod over a very short path, hence the impulse of the piston rod when hitting the piston does not cause any problems.

The invention proceeds from the basic concept of replacing a completely filled syringe with a partially filled syringe in which, as opposed to the completely filled syringe, the piston is situated further in the distal position. Such syringes are also referred to as prefillable syringes, such as for example Hypak^® by Becton Dickinson. A 1 ml syringe is preferred, which can for example be partially filled with 0.1 to 0.9 ml, wherein the filling quantity can for example be varied in increments of 0.1 ml. The injection device can thus be used for syringes which are filled with different dosages, which increases the therapeutic range within which the injection device can be used. If the injection device is fitted with a syringe which is only partially filled, the idle stroke of the piston rod and therefore the path within which the piston rod can accelerate is increased. The impulse of the piston rod when hitting the piston of a partially filled syringe is therefore greater than in the case of a full syringe. Under certain circumstances, the syringe body - which is for example formed from glass - could be damaged by an increased impulse.

It is therefore an object of the invention to provide an injection device, in particular an auto- injector, which exhibits an increased range of application but is still no trouble to handle.

The object is solved by the subject matter of the independent claim. Advantageous further developments follow from the dependent claims, the description and the figures.

The invention proceeds from a device for administering, in particular automatically administering, a liquid product, in particular a drug. The device can be an administering device or injection device, in particular an auto -injector. In an auto-injector, the product to be delivered is at least automatically delivered. In an auto-injector, the needle is preferably moved out of an initial position, in which it is situated within a housing, into an inserting position in which the needle protrudes at least partially beyond the housing, in particular to an extent which approximately corresponds to the inserting depth. The auto-injector can also comprise a means which moves the needle out of the inserting position into an end position in which the needle is arranged completely within the housing. Alternatively, the auto-injector can comprise a needle protecting sleeve which is slid over the needle situated in the inserting position, such that the needle is situated within the needle protecting sleeve. Retracting the needle or covering it with a needle protecting sleeve reduces the danger of injury after the injection device has been used. It is correspondingly preferable for the injection device to comprise means for shifting the needle out of the initial position into the inserting position and means which ensure that the needle is covered after the injection, for which purpose means can in particular be provided which retract the needle into the housing or slide a needle protecting sleeve over the needle.

The device comprises a piston which can be shifted out of an initial position in a delivery direction by means of a delivery stroke. The piston is preferably mounted, such that it can be shifted, in a product container which can for example be a carpoule or a syringe. The outer circumference of the piston abuts an inner circumference of the product container, forming a seal. The portion of the product container which forms this inner circumference is preferably cylindrical, such that the piston can be shifted along the cylindrical portion and simultaneously abuts the container wall, forming a seal. The distal end of the product container is configured such that the product situated in the product container can be delivered via said distal end. If the product container is shaped as a syringe, then a needle is fixedly arranged on the distal end. If the product container is shaped as a carpoule, then the distal end comprises a septum which can be pierced by a needle or cannula which can be attached to the distal end of the carpoule and as applicable also detached again. The needle arranged on the distal end of the product container can generally be connected, in a fluid-guiding connection, to the chamber which contains the drug. A product container which is shaped as a syringe can for example comprise a so-called finger flange at its rear end, wherein the finger flange exhibits an outer diameter which is greater than the diameter of the cylindrical portion in which the piston is guided. The proximal end of the product container comprises an opening which is at least large enough that the piston rod can be inserted into the product container through the proximal end of the product container. Preferably, the proximal end of the product container can be considered as part of the portion along which the piston can be shifted and can therefore also exhibit the inner diameter of this portion.

In order to shift the needle which is arranged on the product container, the product container is preferably shifted together with the needle, i.e. shifted, like the needle, out of an initial position into an inserting position and optionally into an end position. To this end, an outer diameter of the portion of the product container along which the piston can be shifted can for example slide along a part of the administering device, such as for example the housing. The product container is preferably accommodated in a product container holder in which it is arranged axially fixed. For a movement of the needle, the syringe and the product container holder are shifted as one unit. The product container holder can hold the syringe axially fixed, for example at the finger flange or at or distally with respect to the portion along which the piston can be shifted, in particular at the portion at which the product container is tapered. As an example, reference is made to PCT/EP2009/052323 which shows a preferred product container holder.

A product container holder which accommodates the product container such that it is supported against being shifted relative to the product container holder, on at least one protrusion of the product container holder which is directed inwards, by means of its tapered region which is arranged distally with respect to its product portion, i.e. the portion in which the piston can be shifted, is generally preferred. It is preferable for there to be a distance between the optionally provided finger fiange on the proximal end of the product container and the product container holder, along the longitudinal axis. If, for example, an impulse which is directed in the delivery direction of the piston is exerted via the piston, then the force is transferred into the product container holder via the tapered region of the product container, while the proximal end of the product container remains substantially load-free, such that the danger of damaging the product container is reduced.

Although the proximal end of the product container is protected by this measure, there exists a danger, when exerting an impulse on the piston of the at least partially filled syringe, of damaging the portion of the product container arranged between the tapered region and the piston. The longer this portion is, the greater the danger of damage.

The invention proceeds from the basic concept of only exerting a relatively strong impulse on the piston once it has been shifted in the delivery direction out of its initial position, which it assumes when the device is supplied to the user, in particular not until towards the end of the delivery stroke.

To this end, the device comprises a multiple-part piston rod which comprises at least a first part and a second part. The first part and the second part can respectively consist of one or more parts each. The second part engages with the first part by means of an engaging member, hence the first part and the second part are connected axially fixed. The engaging member is preferably arranged elastically and in particular formed by an arm and/or integrally on the second part. The engaging member is preferably biased such that it tends to spring, in particular outwards, into engagement with the first part.

The first part and/or the second part can in particular be sleeve-shaped. The first part can surround the second part. The second part can surround a securing means which is described further below. The second part and preferably also the engaging member(s) can be arranged between the securing means and the first part.

The securing means holds the engaging member in its engagement with the first part and is in particular arranged such that the engaging member is prevented from a movement by which it can be moved out of its engagement with the first part. The securing means can in particular be situated, in relation to the longitudinal axis, on the position in which the engaging member is situated. As long as the securing means is at this position, the engaging member cannot be moved out of its engagement with the first part. In preferred embodiments, the securing means is elongated and in particular sleeve-shaped or pin-shaped. The securing means can be anchored to a component on which an advancing structure is also supported in the state of the device as supplied to the user.

The first and second parts which are connected axially fixed can be able to be shifted out of the initial position by the delivery stroke and relative to the securing means during a delivery sequence. The securing means prevents the engaging member from being moved out of its engagement with the first part during the delivery sequence. During the delivery sequence, the multiple-part piston rod slaves the piston in the delivery direction, thus dispensing the product via the needle. The length of the securing means is preferably set such that towards the end of the delivery stroke, the engaging member is moved into a position in which the securing means is outside of the path which the engaging member travels when it is moved out of its engagement with the first part. In other words, at the end of the delivery stroke, the engaging member is in a position in which the securing means does not hold the engaging member in its engagement with the first part or in which the securing means does not grip behind the engaging member. It is thus possible for the engaging member to be moved out of its engagement with the first part towards or at the end of the delivery stroke.

The engaging member is pressed out of its engagement with the first part by an advancing force of for example an advancing spring which is preferably exerted on the first part. The engaging member is in particular shifted beyond the reach of the securing means during the delivery stroke, thus enabling the engaging member to be released from its engagement with the first part, such the first part can be moved by an idle stroke in the delivery direction relative to the second part. The piston is in particular not slaved in this idle stroke, such that the first part is also moved relative to the piston and the product container. Since the inertia of the product situated in the product container no longer brakes the movement of the piston rod, the first part can accelerate during the idle stroke, such that the first part exerts a relatively strong impulse on the piston at the end of the idle stroke, in particular when it hits the piston or the second part. Since the portion between the piston and the tapered region of the product container is comparatively small at the end of the idle stroke, the danger of damaging the product container is reduced.

The first part of the piston rod can abut directly or indirectly against the piston at the end of the idle stroke. The first part of the piston rod is particularly preferably moved in the product container, in particular in the portion along which the piston can be shifted, during the idle stroke. Before the idle stroke is performed, there is a distance in the longitudinal direction between the piston and the first part. This distance is reduced during the idle stroke. The piston rod can be accelerated during the idle stroke by an advancing member such as for example a gas generator or preferably an advancing spring. Before the idle stroke is performed, the distal end of the first part can be arranged proximally with respect to the proximal end of the product container or level with the proximal end of the product container or protruding into the product container. The first part protrudes into the product container at least during the idle stroke and in particular during the product delivery or delivery stroke. The diameter of the preferably cylindrical first part is slightly smaller than the inner diameter of the product container and/or the portion of the product container along which the piston can be longitudinally guided. The piston rod or the first part of the piston rod can be surrounded by an advancing spring, at least one end of which - in particular, the distal end of which - is supported on the first part. Alternatively or additionally, the advancing spring can be arranged within the sleeve-shaped first part of the piston rod. The design using a sleeve- shaped first part is particularly space-saving. The advancing spring can also be arranged within the cylindrical portion of the product container at least during the product delivery, i.e. while the piston is slaved, i.e. during the delivery stroke, or also during the idle stroke. This arrangement saves even more space.

The first part of the piston rod preferably comprises at least one recess for the engaging member, with which the engaging member engages, thus forming the axially fixed engagement between the first part and the second part. The recess is preferably formed on an inner circumferential area of the preferably sleeve-shaped first part. It may additionally be mentioned that the first part can consist of one or more parts. The outer circumference of the first part can comprise the recess for a blocking element which is described further below. An annular gap can be formed between the outer circumference and the inner circumference, wherein the advancing spring is for example arranged in said annular gap. The outer circumference can for example be formed by an outer sleeve and the inner circumference by an inner sleeve, wherein the outer sleeve and the inner sleeve are at least connected, for example latched or welded, to each other, axially fixed. Although the first part can consist of multiple parts, which offers advantages in its manufacture and assembly, the first part could of course also consist of one part, since a multiple-part first part preferably behaves as an integral first part behaves when administering product.

The first part, in particular the inner sleeve of the first part, can comprise multiple recesses for the engaging member which are arranged along the longitudinal axis of the device and spaced apart from each other. Since the product container is only partially filled, i.e. for example exhibits the size for accommodating a quantity of approximately 1 ml of liquid but only contains a quantity of less than or equal to 0.9 ml or 90% or less than or equal to 0.7 ml or 70% of liquid in the state of the device as supplied to the user, then accelerating the piston rod to inadmissibly high values is to be avoided when the piston is still situated in its initial position. Conversely, it should not require any or hardly any effort to adapt the device to product containers which are filled to different degrees. Since the quantity of liquid contained in the product container is dependent on the position of the piston in relation to the product container, a large distance would exist between the piston rod and the piston in the case of a conventional piston rod, hence the piston rod could use this distance as an acceleration path, thus exerting a strong impulse on the piston which could cause the problems mentioned here. It is therefore preferable to arrange the second part of the piston rod between the piston and the first part, such that the effective distance between the piston rod and the piston decreases.

In the state as supplied to the user, the second part assumes different axial positions in relation to the first part depending on the level of liquid in the product container. It is preferable for the first part to comprise multiple recesses for the engaging member, wherein these recesses are each provided for different levels of liquid or axial positions of the piston. In the state of the device as supplied to the user, the engaging member can selectively engage with one of these multiple recesses depending on the level of liquid. The first part can for example comprise recesses which exhibit the position of the second part in relation to the first part for a product container which is filled with 0.9 ml or 0.6 ml or 90% or 60%. When assembling the device, the engaging member of the second part merely needs to be arranged in the corresponding recess, without having to redesign the device, when product containers comprising 0.9 ml or 0.6 ml are selectively used. Due to the idle stroke which follows the delivery stroke, the second part always performs the same stroke - which is the sum of the idle stroke and the delivery stroke - irrespective of the level of liquid in the product container.

The device can optionally comprise a braking means, in particular a damping means, which brakes or damps the movement of the first part during the idle stroke. In a partially filled syringe, in which a relatively large idle stroke is performed, this can reduce the impulse which the piston rod exerts on the piston at the end of the idle stroke, thus avoiding damage to the components of the device. Reference is made to PCT/EP2010/050746 and DE 10 2009 042 389.3 with regard to various braking means.

The device particularly preferably comprises an advancing structure by means of which the needle and/or the product container can be shifted into an inserting position. The piston rod is preferably accommodated in the advancing structure; the piston rod is in particular surrounded by the advancing structure, at least in the initial position. The piston rod can be shifted relative to the advancing structure and is connected, axially fixed, to the advancing structure, at least in the initial position and in particular before a product delivery and before the idle stroke, for example also before and while inserting the needle. To this end, the advancing structure can comprise a blocking element which engages with the piston rod, in particular with the first part of the piston rod or its outer sleeve, in particular with a recess formed on it. The blocking element can for example be elastically formed on an arm, in particular integrally, on the advancing structure. The blocking element can in principle be moved transverse to the longitudinal axis and/or direction of movement of the advancing structure or product container or needle, wherein when the needle is in its initial position, the blocking element is for example surrounded by an element such as for example the housing which holds the blocking element in its engagement with the piston rod. The element or the housing can comprise a recess, wherein the blocking element can latch into this recess at the end of the inserting movement and is then simultaneously moved out of its engagement with the piston rod. This releases the piston rod for a movement relative to the advancing structure. Due to the axially fixed connection between the first part and the second part, the released piston rod can perform the delivery stroke by which the product is delivered. It is preferable for the first part of the piston rod to be stationary relative to the advancing structure by means of the releasable engagement as it is shifted into the inserting position and for it to be able to be moved relative to the advancing structure during the delivery stroke and the idle stroke. The advancing structure and the piston rod can be able to be shifted by at least one advancing spring, in particular by one advancing spring each, or by a common advancing spring. The advancing spring(s) is/are preferably helical or coil springs made of metal, which act as pressure springs. Springs which act as tensile springs are also conceivable in principle. Optionally, an arrangement comprising a flat spiral spring can also be provided, as disclosed for example in EP 0 666 084 Bl . Particularly preferably, an advancing spring can be provided, the proximal end of which is supported on an element which does not form part of the advancing structure or the piston rod and the proximal end of which is supported on the piston rod, preferably on the first part of the piston rod, wherein the force of the biased advancing spring is routed into the advancing structure via the piston rod and the blocking element. The advancing structure is preferably connected, axially fixed, to or comprises the product container and/or the product container receptacle, such that a movement of the advancing structure generates a movement of the product container and the needle. Alternatively, a spring which is supported distally on the advancing structure can be provided for advancing the advancing structure, and another spring which is supported distally on the piston rod, preferably on the first part of the piston rod, can be provided for advancing the piston rod. The proximal end of said other spring can for example be supported on the advancing structure. An embodiment comprising two advancing springs is however less preferred, since two springs are generally more expensive than one spring.

If the device includes a means for retracting the needle into the device, it is preferable for the securing means to be axially level with the engaging member or for the engaging member to grip behind it after the product has been administered and when the needle is retracted into the device. The first part can for example comprise another recess with which the engaging member engages in this position. Alternatively, the proximal end of the first part can be moved past the engaging member, i.e. can be situated distally with respect to the engaging member. This means that the engaging member can be slid over the securing means when the needle is retracted, wherein there is sufficient space for the engaging member to correspondingly spring outwards. The needle which is fixedly attached to the product container is preferably retracted by a retraction spring - which is tensed during the inserting sequence - exerting a retraction force on the product container holder, in particular indirectly, wherein the product container holder is moved in the proximal direction relative to the housing, thus also retracting the product container accommodated in the product container holder. The device preferably comprises a so-called push-on-skin trigger. To this end, the device can comprise an operating sleeve which protrudes beyond the distal end of the housing, wherein in order to trigger administering, the distal end of the device is pressed against the desired insertion point, thus sliding the operating sleeve into the housing. The operating sleeve is preferably connected, axially fixed, to the securing means, for example via a switching sleeve. In the state of the device as supplied to the user, the advancing structure can be axially supported on the part which the securing means is connected to, axially fixed, such as for example to the switching sleeve or the operating sleeve. Since the advancing structure is axially supported, it can hold the advancing spring in a tensed state.

The optionally provided braking means preferably comprises a part which is separate from the first part of the piston rod and the product container, in particular a braking member or damping member. The braking means, in particular the separate part, is arranged such that it is surrounded by the product container, at least during the idle stroke and optionally also when the needle is in its initial position or before the idle stroke.

The path by which the piston is shifted relative to the product container during the idle stroke is for example smaller than the path which the first part of the piston rod travels relative to the product container during the idle stroke. This also encompasses the special case in which the piston is not moved at all during the idle stroke, i.e. is stationary relative to the product container. The path of the piston would then be equal to zero.

It is in principle possible for the movement energy of the first part to be dissipated between the first part and the second part or the product container during the idle stroke. The first part can for example be in factional engagement with the inner circumference of the product container, such that the movement of the first part relative to the product container is damped. In this example, the movement of the piston rod is braked and/or damped by the braking means both during the delivery stroke and during the remaining stroke or while the first part, the second part and the piston are moved together relative to the product container without moving relative to each other.

The braking means is preferably configured such that the movement of the piston rod is only damped during the idle stroke and in particular not during the delivery stroke. This can for example be realised by forming the braking means between the first part and the second part of the piston rod. Since the second part is axially supported on the piston during the idle stroke, the first part can be moved relative to the second part during the idle stroke. While the piston is slaved, i.e. during the delivery stroke, there is no relative movement between the second part and the first part of the piston rod, such that no braking effect is achieved at least by this braking means. The braking effect of the piston and fluid friction remain unaffected by this. The braking means and in particular the unit consisting of the first part and the second part are axially fixed relative to the piston while the piston is slaved.

It is generally preferred if the second part is elongated and supported on the piston. The second part can slide through a passage, in particular a bore, of the first part which is formed at the distal end.

The braking engagement which brakes and/or damps the movement of the first part is preferably formed in the region of the passage along which the second part is guided and which can also be referred to as the effective region. The inner diameter of the effective region or the effective region for the second part can preferably be formed at the distal end of the first part of the piston rod. This inner diameter can generally be provided by a bore.

In one embodiment, a frictional element which forms the braking engagement can be provided on at least one of the first part and the second part. This frictional element can for example be formed by a rubber ring or a similarly elastic material which is attached to the inner diameter of the effective region and is in frictional engagement with the second part which in this example can exhibit a level or smooth outer diameter. This outer diameter can be essentially cylindrical or can be tapered in the longitudinal direction, in particular in the distal direction, such that damping at the end of the idle stroke is less than at the beginning of the idle stroke. The surface area of the second part can then be conical.

The invention has been described on the basis of multiple preferred embodiments. In the following, the invention is described on the basis of figures. The features disclosed in the figures, individually and in combination, including with the embodiments described above, advantageously develop the invention. There is shown:

Figure 1 an exploded representation of the individual parts of an injection device; Figures 2a and 2b sectional representations of the injection device, with a cap removed and in an activated state, wherein Figure 2b is a view which is rotated by 90° about the longitudinal axis as compared to Figure 2a;

Figures 3a and 3b sectional representations of the injection device from Figure 1, with the needle inserted, wherein Figure 3b is a view which is rotated by 90° about the longitudinal axis as compared to Figure 3 a;

Figures 4a and 4b sectional representations of the injection device from Figure 1 at the beginning of a delivery stroke, wherein Figure 4b is a view which is rotated by 90° about the longitudinal axis as compared to Figure 4a;

Figures 5a and 5b sectional representations of the injection device from Figure 1 at the end of the delivery stroke and beginning of an idle stroke, wherein Figure 5b is a view which is rotated by 90° about the longitudinal axis as compared to Figure 5 a;

Figures 6a and 6b sectional representations of the injection device from Figure 1 at the end of the idle stroke, wherein Figure 6b is a view which is rotated by 90° about the longitudinal axis as compared to Figure 6a;

Figures 7a and 7b sectional representations of the injection device from Figure 1 at the end of a remaining stroke, wherein Figure 7b is a view which is rotated by 90° about the longitudinal axis as compared to Figure 7a;

Figures 8a and 8b sectional representations of the injection device from Figure 1, in which the needle is retracted into the injection device, wherein Figure 8b is a view which is rotated by 90° about the longitudinal axis as compared to Figure 8a.

Unless otherwise stated, identical reference signs refer to the same parts.

Figures 1 to 8 show an injection device such as is known for example from DE 10 2007 013 838, without the means comprising a time-constant delivery signal but with a telescopic piston rod in accordance with the invention.

A product container 2 which is shaped as a syringe is accommodated in a housing 1, and an injection needle 4 for delivering a liquid product contained in the product container 2 is situated at the distal end of the product container 2. The product container 2 comprises a piston 3 which can be shifted and which, when moved relative to the product container 2 and in the direction of the injection needle 4, causes a product delivery, for which reason this can also be referred to as a delivery movement or delivery sequence. The product container 2 is accommodated in the device in such a way that it can be shifted in the distal direction, such that the injection needle 4 protrudes from the distal end of the injection device in accordance with the desired inserting depth. This can therefore be described as an inserting movement or inserting sequence. The product container 2 is connected, axially fixed, to a holder 10 for the product container 2. A shoulder of the product container 2 which is formed distally with respect to the product portion is supported in the distal direction on the holder on projections which are directed inwards, as described for example in PCT/EP2009/052323. The housing 1 comprises a viewing window 12 through which the user of the injection device can view the product container 2. The holder 10 surrounds the product container 2 in the shape of a sleeve, such that in order to allow the container 2 to be viewed, it either comprises a viewing window itself or - as in this example - comprises a transparent material. The holder 10 is connected, axially fixed, to a functional sleeve 11 arranged proximally with respect to it, by means of hooks which are formed at the proximal end of the holder 10. The proximal end of the product container 2 comprises a radially projecting finger flange which is not in contact with the proximal end of the holder 10 in order to protect against damage. The distal end of the functional sleeve 11 comprises at least one axial abutment which is axially flush with the cylindrical piston guiding portion of the product container 2, i.e. which in particular does not abut against the projections of the finger flange. The product container 2, the functional sleeve 11 and the holder 10 are thus connected to each other, axially fixed, such that they can be moved as a single part. In the following, this combination is referred to as the advancing structure 2, 10, 11.

The injection device also comprises a multiple-part piston rod 51, 52, 53 which comprises a first sleeve-shaped part 51, 52 which consists of an outer sleeve 51 which is fixedly snapped onto an inner sleeve 52, and a second sleeve-shaped part 53 which can be telescopically slid into the first part 51, 52. The inner sleeve 52 comprises multiple recesses 52a, 52b which are arranged spaced apart from each other along the longitudinal axis L. The distal end of the second part 53 of the piston rod 51, 52, 53 comprises a widened flange via which it can be supported on the piston 3 of the product container 2. The proximal end of the second part 53 comprises an engaging member 53a which is elastically arranged on an arm and, in the initial state of the injection device or the state of the injection device as supplied to the user, selectively engages with one of the recesses 52a, 52b depending on the level of liquid in the partially filled product container 2.

If the device from DE 10 2007 013 838 were fitted with a partially filled syringe, there would be a relatively large distance between the piston rod and the piston, wherein said distance serves as an acceleration path for the piston rod when the piston rod is released, hence a very strong impulse would be exerted on the piston when the piston rod hits. In order to avoid this, the second part 53 is arranged between the first part 51 , 52 and the piston 3 and thus reduces the distance between the piston rod 51 , 52, 53 and the piston 3. The second part 53 is connected, axially fixed, to the first part by means of the engaging member 53a which engages with the first part, i.e. with the inner sleeve 52 (Figures 2a, 2b). The engaging member 53a engages with one of the multiple recesses 52a, 52b, depending on the level of liquid in the partially filled syringe 2, and preferably with the one which causes the second part 53 to be arranged the nearest to the piston 3. In the example shown in Figure 2a, the engaging member 53a is arranged in a recess 52a which allows the use of the product container 2 with a filling quantity of 0.6 ml. The recess 52b would allow a filling quantity of 0.9 ml. If the syringe 2 were completely filled, it could accommodate 1 ml.

The inner sleeve 52 also comprises another recess 52c with which the engaging member 53a engages at a later point in time, namely when the second part 53 is completely slid into the first part 51 , 52.

The injection device also comprises a securing means 60 which is configured as an elongated pin which is anchored, axially fixed, in a switching sleeve 8. The securing means 60, which is for example formed from metal, prevents the engaging member 53a from being able to be moved out of its engagement with the recess 52a, in particular during a delivery stroke S_d. The securing means 60 blocks a movement of the engaging member 53a out of the recess 52a by being arranged axially level with the engaging member 53a.

The device also comprises an advancing spring 6 which is biased when the injection device is in the state shown in Figures 2a and 2b, such that it can advance the needle 4 and in particular the advancing structure 2, 10, 1 1 for an inserting movement and the piston rod 51, 52, 53 for a delivery stroke S_d and an idle stroke Si. The advancing spring 6 is arranged in an annular gap formed between the inner sleeve 52 and the outer sleeve 51 , wherein its distal end is supported on the first part 51, 52 and its proximal end is supported on the switching sleeve 8, in particular on a skirting 8a formed on it. The advancing spring 6 surrounds the second part 53 of the piston rod 51, 52, 53 and surrounds the securing means 60.

The functional sleeve 11 surrounds the piston rod 51, 52, 53 and comprises a blocking element 16, wherein a shoulder which is directed radially inwards is formed on the blocking element 16 and co-operates, in the initial state, with a shoulder which is formed at the distal end of the first part 51 , 52 or the outer sleeve 51 , such that the piston rod 51 , 52, 53 is blocked against moving relative to the functional sleeve 11. The blocking element 16 is held in its engagement with the piston rod 51, 52, 53 by an area of the switching sleeve 8 which points radially inwards. Preferably, the blocking element 16 is elastically connected, in particular integrally, to the functional sleeve 11 via a spring arm. The elastic arrangement can be configured such that the blocking element 16 tends to move radially outwards, wherein this is prevented by the area of the switching sleeve 8 which points radially inwards.

The proximal end of the functional sleeve 11 comprises at least one snap element 15 which snaps into the switching sleeve 8 in the initial state in order to prevent a movement of the functional sleeve 11 and therefore the advancing structure 2, 10, 11. This means that the biased spring 6 cannot yet be relaxed and that the advancing structure 2, 10, 11 cannot yet move in the distal direction (Figures 2a and 2b).

The proximal end of the housing 1 of the injection device comprises an activating element 13 which is arranged on the housing 1 such that it is axially fixed but can be rotated. The activating element 13 accommodates a restoring spring 21 which is distally supported on the skirting 8a of the switching sleeve 8 and proximally supported on the activating element 13. The restoring spring 21 has the task of charging the switching sleeve 8, and an operating sleeve 9 which acts axially on the switching sleeve 8, with a force which acts in the distal direction, such that the switching sleeve 8 and the operating sleeve 9 are pressed in the distal direction. The activating element 13 comprises an activating block 14 which can be rotated from a position in which it grips behind the snap element 15, such that the snap element 15 is blocked and/or secured against moving out of its engagement with the switching sleeve 8, into the position shown in Figures 2a and 2b in which it does not grip behind the snap element 15. It is thus advantageously possible to prevent the injection device from being inadvertently triggered. The activating block 14 can be moved out of its engagement with the snap element 15 by rotating the activating element 13 by for example 90° relative to the housing 1.

A retraction spring 7 which acts in the longitudinal direction of the device is distally supported on the switching sleeve 8 and proximally supported on the functional sleeve 1 1. As shown in this example, the retraction spring 7 surrounds the switching sleeve 8 and the functional sleeve 11. The retraction spring 7 is in particular proximally supported on a collar 1 1a which is formed by the functional sleeve 1 1 and grips radially outwards through a breach which is formed in the switching sleeve 8. The retraction spring 7 can therefore generate a relative movement between the switching sleeve 8 and the functional sleeve 1 1 in particular switching positions. The retraction spring 7 is a pressure spring which can move the functional sleeve 1 1 in the proximal direction relative to the switching sleeve 8. The retraction spring 7 is not biased or preferably only biased with a small biasing force such as for example half the force of the injection spring 6. When the injection device is in the state shown in Figures 2a and 2b, the biasing force of the retraction spring 7 is for example less than the biasing force of the advancing spring 6. The retraction spring 7 is in particular tensed with a greater force than the advancing spring 6 at the end of the idle stroke Si.

The operating sleeve 9 is arranged distally with respect to the switching sleeve 8 and such that it can be moved relative to the housing 1. The switching sleeve 8 and the operating sleeve 9 can respectively and reciprocally charge each other with a compressive force and can in particular be latched to each other and thus shifted. In order for the operating sleeve 9 to not block the view onto the product container 2, it likewise comprises a window in the region of the window 12. Alternatively, the operating sleeve 9 can be formed from a transparent material. In the initial state, the operating sleeve 9 is advanced distally beyond the distal end of the housing 1 by the restoring spring 21 via the switching sleeve 8. The distal end of the operating sleeve 9 serves for being placed on an injection point on a patient for a push-on- skin trigger.

The holder 10 comprises a switching cam 17 which engages with a cavity 18 of the operating sleeve 9 which, as shown in this example, can be a breach. The switching cam 17 is elastically connected, in particular integrally, to the holder 10, for example via an elastic arm. The switching cam 17 is preferably biased such that it tends to engage with the cavity 18 and/or be moved radially outwards. The switching cam 17, which projects radially outwards from the holder 10, distally comprises an oblique area which can then aid in pressing the switching cam 17 out of its engagement with the cavity 18. Proximally, the switching cam 17 also comprises an abutment area which is transverse, in particular perpendicular, to the longitudinal axis L and can enter into axial abutment with the proximal boundary of the cavity 18, wherein the switching cam 17 cannot be moved out of the cavity 18 due to the axial abutment.

The operating sleeve 9 comprises an axial abutment 19 which the distal end of the holder 10 can abut against the end of an inserting movement.

A multiple-part cap 32, 33 (Figure 1) can be arranged on the distal end of the injection device and protects the interior of the injection device from contamination and in particular keeps the needle 4 sterile. The cap 32, 33 is removed before the injection device is used, such that in particular the needle 4 and the operating sleeve 9 are exposed, as shown in Figures 2a and 2b.

The force which is exerted on the injection device when the needle cap 32 is removed is routed onto the functional sleeve 11 via the holder 10 and transferred from the functional sleeve 11 onto the switching sleeve 8, which is supported on the operating sleeve 9, via the snappers 15. The operating sleeve 9 is in turn latched to the housing 1 via a projection Id which is formed by the distal housing part lb, such that removing the cap from the injection device does not have any undesirable effect on the mechanics.

The injection device is activated and/or unlocked by a rotational movement of the activating element 13 by for example 90° (Figures 2a and 2b), wherein the snap elements 15 are released for a movement directed radially inwards, by moving - in particular, rotating - the activating block 14 out of its engagement with the snap elements 15. There is then space for the snap elements 15 to be deflected radially inwards. Like the snap element 15, the activating element 13 also comprises an activating cam 13a which is moved so as to be axially flush with the snap element 15 by the rotational movement of the activating element 13. The snap element 15 proximally exhibits a contour, and the activating cam 13a which is arranged proximally with respect to the snap element 15 distally exhibits a contour, which can deflect the snap element 15 radially inwards when the snap element 15 is moved in an engagement with the activating cam 13a. In this example, the contours are two inclined planes which slide off on each other. In order to trigger the injection device, the user of the device places its distal end onto the injection point which has preferably been disinfected beforehand. This shifts the operating sleeve 9 in the proximal direction relative to the housing 1, preferably until the distal end of the operating sleeve 9 is approximately flush with the distal end of the distal housing part lb. The switching sleeve 8 is slaved in the proximal direction by the movement of the operating sleeve 9, wherein the snap elements 15 are pressed out of their engagement with the switching sleeve 8, in particular radially inwards, by means of the activating cams 13a. The movement of the operating sleeve 9 in the proximal direction also slaves the elements of the advancing structure 2, 10, 11 and the securing means 60 in the proximal direction as long as the snap elements 15 are snapped into the switching sleeve 8. Since the piston rod 5 is in a blocking element with the functional sleeve 11 , the piston rod 5 is also slaved in the proximal direction. Since there cannot yet be any relative movement between the functional sleeve 11 and the switching sleeve 8 during this movement, neither the retraction spring 7 nor the advancing spring 6 are tensed or relaxed.

The force which the user of the device has to exert on the housing 1 in order for the operating sleeve 9 to be shifted in the proximal direction is substantially defined by the force of the restoring spring 21 against which the switching sleeve 8 and the operating sleeve 9 are moved. The spring 21 is preferably a pressure spring and is formed from a plastic material. Alternatively, springs 21 made of a spring steel material or other spring material can of course also be used. The activating element 13 is axially attached to the housing 1 in the form of a snap connection with the housing 1. If the operating sleeve 9 is not pressed far enough onto the injection point, such that the snap elements 15 are not released from their engagement with the switching sleeve 8, then the triggering mechanics, for example the switching sleeve 8 and the operating sleeve 9, are reset by the restoring spring 21 when the injection device is removed from the injection point.

As can be seen from Figures 2a and 2b, the movement of the operating sleeve 9 in the proximal direction forms a blocking window 20 which is distally limited by the housing 1 , in particular the projection Id, and proximally limited by the operating sleeve 9. Since there is not yet any relative movement between the advancing structure 2, 10, 11 and the operating sleeve 9 during the movement of the operating sleeve 9 in the proximal direction, the switching cam 17 remains in the cavity 18. Once the snappers 15 are latched out of their engagement with the switching sleeve 8, the advancing spring 6 can be partially relaxed, hence the piston rod 51 , 52, 53 and the advancing structure 2, 10, 1 1 are shifted in the distal direction, wherein the injection needle 4 protrudes beyond the distal end of the injection device. Since the functional sleeve 1 1 is moved relative to the switching sleeve 8 during this inserting movement, the retraction spring 7 is compressed, i.e. tensed. During the entire inserting process, i.e. also at the beginning and at the end of the inserting process, the spring force of the advancing spring 6 is greater than the spring force of the retraction spring 7. This has for example the advantage that the inserting force is reduced, which helps to avoid damage to the injection device.

As can be seen from Figures 3a and 3b, which show the situation at the end of the inserting process, the blocking element 16 engages with the cavity 18 by way of a movement which is directed radially outwards and is intended to be shown by the arrows in Figure 3b. In order to improve this engagement, the blocking element 16 comprises a projection which is directed radially outwards. The blocking element 16 fulfils two functions. When the blocking element 16 latches into the cavity 18, the blocking element 16 simultaneously latches out of the first part 51 , 52 of the piston rod 51 , 52, 53 by way of the movement which is directed radially outwards, such that the piston rod 51 , 52, 53 is released for a delivery movement or a delivery stroke S_d. Conversely, the movement of the advancing structure 2, 10, 1 1 in the axial direction, in particular in the proximal direction, is blocked. This process decouples the advancing spring 6 from the retraction spring 7, i.e. such that in this state, the advancing spring 6 has no effect on the bias of the retraction spring 7. This is followed by a delivery movement comprising the delivery stroke S_d which the piston rod 51 , 52, 53 performs relative to the functional sleeve 1 1. The first part 51 , 52 and the second part 53 which is connected, axially fixed, to the first part 51 , 52 are shifted by the delivery stroke S_d, wherein the second part 53 abuts against the piston 3 and slaves it (Figures 4a and 4b).

As shown in Figure 4a, the securing means 60 grips behind the engaging member 53a at the beginning of and during the delivery stroke S_d, such that the first part 51 , 52 and the second part 53 remain connected, axially fixed. During the delivery stroke S_d, the first and second parts 51 , 52, 53 are moved along the securing means 60. The securing means 60 exhibits a particular length along the longitudinal axis L which is set such that the engaging member 53a is outside of the reach of the securing means 60 at the end of the delivery stroke S_d. In this example, the engaging member 53a is situated distally with respect to the distal end of the pin- shaped securing means 60. The delivery stroke Sd moves the engaging member 53a past the distal end of the securing means 60, such that the securing means 60 no longer holds the engaging member 53a in its engagement with the recess 52a, as can best be seen in Figure 5a. The force of the advancing spring 6 on the first part 51, 52 presses the engaging member 53a out of its engagement with the recess 52a, such that the first part 51, 52 can be moved in the delivery direction relative to the second part 53. The first part 51, 52 can thus perform an idle stroke Si relative to the second part 53. During the idle stroke Si, the piston 3 is stationary relative to the product container 2.

If an optionally provided braking means is not provided, the first part 51, 52 can accelerate during the idle stroke Si due to the spring force of the advancing spring 6, wherein at the end of the idle stroke Si, it hits the flange of the second part 53 which abuts the piston 3, wherein it generates a clicking sound (Figure 6b). Since the distance between the piston 3 and the tapered region of the product container 2 is small as compared to the original position of the piston 3 (Figures 2a and 2b), the danger of the product container 2 being damaged or destroyed by the impulse generated by the first part 51, 52 hitting the second part 53 is reduced. The danger of damage is also reduced by the fact that the spring force of the advancing spring 6 during the idle stroke Si is less than during the delivery stroke Sd, since the advancing spring 6 is relaxed during the delivery stroke Sd.

At or towards the end of the idle stroke Si, the elastically arranged engaging member 53a snaps into the recess 52c which lies proximally with respect to the recesses 52a and 52b.

Not least due to production tolerances, the piston rod 51, 52, 53 can move the piston 3 in the delivery direction by a remaining stroke S_r, wherein the first and second parts 51, 52, 53 are moved as one unit together with the piston 3 due to the spring force of the advancing spring 6. Figure 6b shows the piston 3 and/or piston rod 51, 52, 53 before the remaining stroke S_r, and Figure 7b shows the piston 3 and/or piston rod 51, 52, 53 after the remaining stroke S_r has been performed.

No additional force due to the inserting process is noticeable to the user of the device. Said force is captured by the snapping between the operating sleeve 9 and the switching sleeve 8 and is not supported on the housing. The force for the inserting process is routed onto the collar of the product container 2 via the functional sleeve 11. The inserting process is thus positively controlled, since the functional sleeve 1 1 advances the product container 2 up until the end of the delivery, and the piston rod 51 , 52, 53 cannot deliver until the blocking elements 16 have engaged with the cavities 18. The inserting movement is stopped by the abutment 19 on the operating sleeve 9.

During the inserting movement, the switching cam 17 is pressed out of its engagement with the cavity 18 of the operating sleeve 9, due to a chamfer of the distal boundary (edge) of the cavity 18 which is formed on the switching cam 17 and points in the distal direction, and shifted in the distal direction such that it latches into the blocking window 20 as shown for example in Figures 3b and 4b. The blocking element 16 which is latched into the cavity 18 is in contact with the proximal boundary of the cavity 18. Since the blocking element 16 and the switching cam 17 exhibit a defined distance due to their axially fixed arrangement with respect to each other, it is preferable for there to be a small distance, which in this example measures 0.5 to 1 mm, between the proximal end of the switching cam 17 and the distal end of the blocking window 20 when the blocking element 16 is in engagement with the cavity. As explained further below, this distance is used to generate a haptic or acoustic signal which is intended to signal that the product has been completely delivered.

Figures 6a to 7b show the injection device in a state after the delivery stroke S_d and the idle stroke Si have been performed. During the delivery stroke S_d and the idle stroke Si, the outer circumferential area of the outer sleeve 51 presses the blocking element 16 into the cavity 18, thus securing the blocking element 16 against latching out of the cavity 18 during a product delivery. The outer sleeve 51 can comprise a cavity or its length can be set such that the blocking element 16 is no longer secured by the outer circumferential area of the outer sleeve 51 once the product has been delivered, such that the blocking element 16 can latch out of the cavity 18. The blocking element 16 can latch out due to an elastically biased arrangement of the blocking element 16 or due to the geometry of the blocking element 16 which causes the blocking element 16 to be pressed out of the cavity 18.

At the end of the idle stroke Si, the advancing spring 6 has been relaxed further, while the tension in the tensed retraction spring 7 has remained constant. The spring force of the advancing spring 6 is then less than the spring force of the biased retraction spring 7. By releasing the engagement between the blocking element 16 and the cavity 18, the retraction spring 7 and the advancing spring 6 are coupled to each other again. This coupling means that the aforementioned small distance disappears, since the proximal end of the advancing structure 2, 10, 11, i.e. in particular the switching cam 17, is moved abruptly onto the distal end of the blocking window 20. A haptic and/or acoustic signal is generated when the switching cam 17 strikes. This movement by the small path does not yet however draw the needle 4 completely out of the patient. The patient and/or user of the device can then wait any amount of time until the needle 4 is drawn completely out of the patient, since the patient and/or user can start the device's automatic needle retraction as desired.

It is not yet possible for the needle to move completely into the distal end of the housing 1, since the switching cam 17 is in its engagement with the blocking window 20 and thus blocks the spring 7 against being relaxed. In order to allow the needle 4 to be retracted, the user of the device merely needs to remove the device from the injection point. The restoring spring 21 can then move the operating sleeve 9 in the distal direction via the switching sleeve 8, wherein the advancing structure 2, 10, 11 is stationary relative to the operating sleeve 9, such that the switching cam 17 - due to its distal configuration - is pressed radially inwards out of the blocking window 20 by means of the projection Id, driven by the spring 21 in conjunction with the operating sleeve 9. As soon as the switching cam 17 has been pressed inwards, the needle is free to be retracted. Releasing the engagement also releases the retraction spring 7 for a retraction movement. Due to the greater spring force of the biased retraction spring 7, the entire advancing structure 2, 10, 11 is pressed in the proximal direction, wherein the spring 6 is tensed again, wherein the spring force of the retraction spring 7 is greater than the spring force of the advancing spring 6 during the entire retraction process, i.e. even up until the end of the retraction process.

During the retraction movement of the needle 4, the product container 2 is also moved in the proximal direction together with the piston 3 and the first part 51, 52 and second part 53 of the piston rod 51, 52, 53, in particular relative to the securing means 60. During retraction, the engaging member 53a which engages with the recess 52c is slid over the securing means 60, such that the securing means 60 grips behind the engaging member 53a (Figure 8a).

In its end state (Figures 8a and 8b), the injection device again has the same dimensions as at the beginning. It is thus also possible to replace the cap 32, 33 and dispose of the injection device. In the end position, the needle 4 is completely retracted into the distal end of the device. The snap element 15 is again latched to the switching sleeve 8, as at the beginning. It is not however possible to trigger the injection device again, since this would necessitate a biased advancing spring 6 such as is for example shown in Figures 2a and 2b.

List of reference signs

1 housing 15 snap element

Id projection 16 blocking element

2 product container 17 switching cam

3 piston 18 cavity

4 injection needle 19 axial abutment

5 piston rod 20 blocking window

6 advancing spring 21 restoring spring

7 retraction spring 32 rigid needle shield

8 switching sleeve 33 cap

8a skirting 51 outer piston rod sleeve / first part

9 operating sleeve 52 outer piston rod sleeve / first part

10 product container holder 53 telescopic sleeve / second part

1 1 functional sleeve 60 securing means / pin

1 1a collar L longitudinal axis

12 viewing window s_d delivery stroke

13 activating element Si idle stroke

13a activating can s_r remaining stroke

14 activating block

Claims

Patent claims

1. A device for automatically administering a product, comprising a piston (3) which can be shifted out of an initial position in a delivery direction by a delivery stroke (Sd), said device also comprising:

a) a multiple-part piston rod which comprises a first part (52) and a second part (53) which engages with the first part (52) by means of an engaging member (53a), hence the first part (52) and the second part (53) are connected axially fixed;

b) and a securing means (60) which holds the engaging member (53a) in its engagement with the first part (52);

characterised in that

c) the first and second parts (52; 53) which are connected axially fixed can be shifted by the delivery stroke (Sd) and relative to the securing means (60); and

d) the engaging member (53 a) can be shifted beyond the reach of the securing means (60) by means of the delivery stroke (Sd), thus enabling the engaging member (53a) to be released from its engagement with the first part (52), such the first part (52) can be moved in the delivery direction, in particular by an idle stroke (Si), relative to the second part (53).

2. The device according to claim 1 , characterised in that the piston (3) is mounted, such that it can be shifted, in a product container (2), in particular a carpoule or a syringe, and the first part (52) and the second part (53) can be moved into or in the product container (2).

3. The device according to any one of the preceding claims, characterised in that the first part (52) comprises a recess (52a; 52b) for the engaging member (53a), with which the engaging member (53a) engages for the axially fixed engagement.

4. The device according to any one of the preceding claims, characterised in that the first part (52) comprises multiple recesses (52a, 52b) for the engaging member (53a) which are arranged along the longitudinal axis (L) of the device and spaced apart from each other, wherein it is preferable for the engaging member (53 a) to selectively engage with one of these multiple recesses (52a; 52b) in the state of the device as supplied to the user.

5. The device according to any one of the preceding claims, characterised in that the engaging member (53 a) is arranged elastically, in particular via an arm and/or integrally, on the second part (53).

6. The device according to any one of the preceding claims, characterised in that the first part (52) and the second part (53) are sleeve-shaped, wherein the first part (52) and the second part (53) surround the securing means (60).

7. The device according to any one of the preceding claims, characterised in that the first part (52) consists of one or more parts and/or in that the first part (52) comprises an annular gap in which an advancing spring (6) is arranged.

8. The device according to any one of the preceding claims, characterised in that the securing means (60) is elongated and in particular sleeve-shaped or pin-shaped and preferably anchored in the component (8; 8a) on which the advancing structure (1 1) is supported in the state of the device as supplied to the user.

9. The device according to any one of the preceding claims, characterised in that the product container (2) is only partially filled and for example exhibits the size for accommodating a quantity of approximately 1 ml of liquid but only contains a quantity of less than 0.9 ml or less than 0.7 ml of liquid in the state of the device as supplied to the user.

10. The device according to any one of the preceding claims, characterised by an advancing structure (1 1) by means of which a needle (4) and/or the product container (2) can be shifted into an inserting position, wherein the piston rod (5) is stationary relative to the advancing structure (1 1) by means of a releasable engagement as it is shifted into the inserting position and can be moved relative to the advancing structure (1 1) during the delivery stroke (S_d), wherein the advancing structure (1 1) and the piston rod (5) can be shifted by at least one advancing spring, in particular by one advancing spring each, or by a common advancing spring (6).

11. The device according to any one of the preceding claims, characterised by a braking means, in particular a damping means, which brakes or damps the movement of the first part (52) during the idle stroke (Si).

12. The device according to any one of the preceding claims, characterised by a product container holder (10) which accommodates the product container (2) such that it is supported, against being shifted relative to the product container holder (10), on at least one protrusion of the product container holder (10) which is directed inwards, by means of a tapered region which is arranged distally with respect to its product portion, wherein it is preferable for there to be a distance between an optionally provided finger flange on the proximal end of the product container (2) and the product container holder (10), along the longitudinal axis (L).

13. The device according to any one of the preceding claims, characterised in that the device is configured such that a needle (4) can be automatically inserted, in particular by means of an inserting sequence, and the product can be automatically delivered, in particular by means of a delivery sequence, and the needle (4) can optionally be automatically retracted into the device by means of a retracting sequence or a needle protecting sleeve can be slid over the needle (4).

14. The device according to any one of the preceding claims, characterised in that the securing means (60) is axially level with the engaging member (53 a) after the product has been administered and when the needle (4) is retracted into the device.