Automatic injector and cartridge or ampoule for use in injectors

ABSTRACT OF THE DISCLOSURE

Automatic injection device, as well as ampoule or cartridge for the same. in order to obtain a high speed discharge of an ampoule-hypodermic needle, as well as to ensure an operationally reliable, low weight, robust small apparatus or ampoule at long storability, sterility and reusability of components for a plurality of injection substances, the needle body of the cannula hypodermic needle is constructed over part of its extension as a needle bearing guided in sliding fit on the inner wall of the ampoule. Particularly with a view to administering separate injection substances, it is provided for an ampoule with needle and lifting element, that within the ampoule there is arranged a receptable forming a gas volume, which receptacle can be destroyed easily by initiating the lifting movement and which is resistant to the injection fluid surrounding it.

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- ι The present invention relates to an automatic injection device.

In particular, the invention relates to an automatic injection device or hypodermic syringe, of the type comprising an elongated casing; a cartridge, ampoule, phial or like receptacle for holding an injection substance which receptacle is mounted in the casing, has a lifting element, surrounds an injection or hypodermic needle including an elongated needle body and a cannula or tubule, the needle being movable by the lifting element and having a cannula inlet opening for the injection substance in the region of its drive-side end and comprises a seal arranged on the side of the needle point and permitting the passage of the needle shaft; an injection pressure device mounted on the casing and applying a force to the lifting element; a release mechanism putting the pressure device into operation; and a safety device for blocking the release mechanism; and the invention further relates to a cartridge, ampoule, phial or like receptacle for holding an injection substance and for use in an injection device, particularly in an automatic hypodermic syringe, the injection substance in the receptacle being ejectable, as a result of the lifting movement of a lifting element, such as in particular a plunger or bolt, through a cannula of an injection needle mounted on the receptacle.

Automatic self-injection syringes are mainly

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- 2 to give unskilled persons an opportunity of subcutaneous or intramuscular self-injections. This has particular significance in connection with the injection of atropine sulphate as a nerve gas preventative. In addition, atropine is injected as an effective antidote in the case of insecticide poisonings. Atropine is also indicated, e.g. in the case of spasms and colics in the gastrointestinal tract, in the gall bladder or the discharging urinary passages, of bladder tenesmus, of hypersecretion of the stomach, of gastric and duodenal ulcers, bronchial asthma and in higher doses and over longer periods in the case of Parkinsonism. An automatic injection device can, in general, be used for the application of a large number of injection substances in human or veterinary medicine. Possibilities of use also exist in the technical field. Thus, in particular dangerous or toxic substances can be introduced into soft materials, mention being, for example, made of the preservation of soft wood or similar treatments. The injection substances can be constituted by liquids, gases or pressure-liquifiable substances.

Essential demands made on automatic injection devices reside in sterility, durability and stability even over long periods of storage, in the ability of very rapid and reliable penetration of tissue parts having pain receptors by the needle, if necessary also after piercing articles of clothing, in low weight and compact

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- 3 construction, as well as in simple and operationally reliable handling.

2. Prior Art

In a known injection device of this type, a needle is mounted in an ampoule by localizing a needle base on a lifting plunger, as well as on the discharge side in a needle guide and a rubber plunger. A helical compression spring engages in the ampoule sleeve for advancing the lifting plunger. In the case of such a construction, the guidance and mobility of the needle are impaired due to the decelerating effect of the relatively long rubber bearing and this can lead to a moment of force having an unfavourable action on the alignment and movement of the needle. A cannula opening provided on the needle base, i.e. a weakened needle portion at this point, can lead to a deformation or even to the breakage of the needle. To ensure the application of an adequate force to the lifting plunger or for driving the needle, a rela20 tively high force is required, which has to be imposed by the helical compression spring having a relatively long extension and a relatively large coil diameter, the spring following the plunger in an inner sleeve mounting both it and the ampoule and engaging in the latter during operation. The ampoule body is made from stainless steel in order to withstand the stress by the force. Due to catalytic effects and chemical and/or galvanic re- 4 1295902 actions of the metal with the injection substance, the stability and effectiveness thereof is reduced. Stainless steel is not inert for many injection substances, so that it cannot be used as ampoule material. The pressure device and, therefore, the complete device have relatively large dimensions, the force efficiency and force guidance being restricted and unfavourable due to constructional conditions. The construction also leads to the risk of inadequate sterility and prevents re-use or reconstruction of the device. In a further known injection device (DE-AS 14 91 842) the needle bearing comprises a plunger with a deformable piston which can yield back into a cylindrical chamber so that mounting and construction are complicated, whilst the usability and efficiency are restricted by constructional and material requirements.

Other automatic injection devices not belonging to the species concerned comprise a needle fixedly attached to a movable ampoule (DE-OS 24 31 347, DE-AS 19 34 117, DE-PS 24 36 000), a cap of an injection cannula being particularly mounted on a needle holder (DE-OS 33 42 407).

3. Objects of the Invention

In contrast thereto, it is a primary object of the present invention to provide an automatic injection device ensuring a high speed ejection of the injection needle whilst providing a uniform and clearly defined injection substance release.

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It is a further essential object of the present invention to provide the arrangement and construction of the needle bearing such as to render usable, in an optimum manner, and/or to improve the possibilities of use and application, the construction and characteristics of the needle, cartridge, drive or pressure device, release mechanism and safety device.

At the same time, it is another object of the invention that the complete device has a long storability as well as a sterility ensuring type of construction of a particularly high mechanic efficiency, and is provided to become operationally reliable, lightweight, robust, compact, of small construction, as well as simple, fast and without risk to handle and to become re-usable, owing to the possibility of an ampoule replacement and of the repeated use of device parts.

A yet further important object of the invention is to provide a compact ampoule capable of being handled as such for an injection device, which shall be effortlessly insertable into an injection device as an independent component and which shall open up the random usability of an injection device for a multitude of injection substances, particularly also for the administration of separate and, therefore, also injection substances not liquifiable per se and chemically reacting with one another on administration.

According to still another object of the invention,

- 6 a construction has the aim which is simple and fail-safe as well and meets medical requirements by a high degree, so that the ampoule is particularly suitable for use in automatic injection devices.

SUMMARY OF THE INVENTION

According to the present invention, there is provided an automatic injection device, comprising a casing; an ampoule, which is mounted in the casing, receives an injection substance, has a lifting element, surrounds an injection needle comprising an elongated needle body and a cannula, the needle being movable by the lifting element and having the cannula inlet opening for the injection substance in the region of its drive-side end, and comprises a seal provided on the side of the needle point and permitting the passage of the needle shaft; an injection pressure device mounted on the casing and applying a force to the lifting element; a release mechanism putting the pressure device into operation; and a safety device for blocking the release mechanism, wherein the needle body, over part of its extension, is designed as a needle bearing guided in a sliding fit on the inner wall of the cartridge.

In the case of an ampoule or cartridge of the type described in the introductory paragraph of the specification, for the administration of separated injection substances, a receptacle such as a capsule forming a gas or dead volume is arranged within the ampoule, the receptacle having a receptacle wall resistant to the injection substance surrounding the receptacle, which receptacle wall is, in particular, not soluble in the injection substance and can easily be destroyed on initiating the lifting movement.

In the case of the integrated needle bearing

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- 6a formed by the needle body, it is, in particular, achieved that the needle or cannula is independently movable and guided in the ampoule in substantially friction-free manner with a type of floating effect in the injection substance.

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1.295902

Thus, the needle can be advanced very rapidly in a substantially delay-free manner, and a high discharge capacity can be obtained. The needle bearing according to the invention is in itself sufficient to guide and position the needle, so that there is no need for further needle bearings, particularly in the ampoule discharge region. During operation the needle is also protected against damage or destruction and its movement and alignment are substantially free from the influences of the mounting of the lifting element or its movement behaviour. This means that the needle bearing is mechanically decoupled with respect to the lifting element or to a pressure device such, that the transmission of force to the needle takes place without any disadvantageous effect on its alignment and whilst preventing damage thereto. This leads to a particularly simple, compact, robust, efficient, operationally reliable and easily handable ampoule and to an instrument with corresponding advantages, whose components are not impaired by the needle bearing as regards sterility as well as operation and re-usability, but can be provided with optimum adaptation and matching thereto.

If a precisely central ejection of the needle is desired, although unnecessary for automatic injection, a spacer disk supporting the needle alignment can be arranged within the ampoule, preferably in the needle ejection region, which disk does not impair the substan1295SC2 tially frictionless mobility of the needle obtained in accordance with the invention.

An embodiment of the needle bearing, according to the invention, consists in that this needle bearing is designed as a lifting element or a drive-side sealing element, and that this bearing is integrated into a lifting plunger or provided with a preferably thinwalled surface serving the needle advance and, in particular, is chargeable with the force of a fluid. Thus, the ampoule becomes particularly small and the needle bearing can serve as the precise guidance and alignment of the lifting plunger or can itself act as the lifting element, the sliding fit, in part, forming the driveside sealing of the ampoule.

It is particularly expedient for the needle bearing, in the case of a cylindrical cartridge or ampoule, to comprise at least one cannula winding establishing the sliding fit and, in particular, a terminal winding engaging on a lifting element constructed as a lifting plunger.

Such a winding cannula ensures a moment-free self-mounting of the needle, the sliding surface and, therefore, also the friction surface on the inner wall of the ampoule being minimized. A single winding leads to a particularly short cannula or needle. In accordance with the desired residual displacement volume, two or more windings can be shaped in closely juxtaposed or spaced manner. Particularly in the case of mass production, a particularly dimensionally accurate alignment of the needle point perpendicularly to the winding body is ensured with respect to a central passage through the ampoule seal.

Due to the design of the needle bearing as a cannula winding the needle may as well be aligned in a particularly simple manner at an angle of approximately 7-15° with respect to the axis of the ampoule (cartridge or phial) or of the winding. The deviation of the angle from the axis is adjusted in accordance with the anatomical circumstances and facts. It is e.g. advantageous to choose a relatively large deviation for self-injections in the posterior region. The engagement of the terminal winding on the lifting plunger effects a delay-free,

i.e. rapid force transfer possible under high force. An arrangement of the cannula inlet opening on the plungerside winding end ensures an optimum fluid entry into and fluid passage through the cannula.

An injection substance quantity as well as a desired administration or application depth for the needle are expediently provided by the number of cannula windings and matched thereto with a compressible gas or dead volume,

i.e. in particular with a gas or air cushion leading to a defined delay of injection substance discharge.

According to a further embodiment of the invention, the needle can be located in a frontal separate ampoule space forming a dead volume and filled with a gas or gaseous mixture and to which, on the drive side, can be

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- ίο connected a rear ampoule space containing the injection substance, separated by a sealing lifting element and formed between the latter and a lifting plunger; and the lifting element can be pierced during actuation by a formation in or on the needle and/or the needle bearing, said formation including the cannula inlet opening.

Thus, there is obtained a cannula mounted in a dry manner in an air or gas space and which is therefore kept sterile. The dead volume, which is compressible to a higher degree with respect to the injection substance, additionally leads to a very short, defined delay of the discharge of the injection substance from the driven needle. In other words, the needle point exits from the ampoule prior to the ejection of injection substance, the delay being determined by the size of the dead volume and/or the distance of the open needle end to the lifting element. The gas or dead space located in defined manner in the front ampoule part ensures a delay independent of the alignment of the ampoule during injection. Freedom from blocking of the cannula opening is, in particular, ensured by a sufficient opening cross-section and/or an opening remote from the needle impact zone. The needle end forming formation in or on the needle can be provided with a grinding and/or made pointed to facilitate the penetration of the lifting element.

For an ampoule for loading an injection device, for an ampoule with a needle bearing according to the inven11

- ii tion and/or for the automatic injection device of the aforementioned type, the invention suggests that within the ampoule and, in particular, between the needle bearing and the lifting element there be provided a gasor dead-volume-forming receptacle, such as a capsule with a receptacle wall resistant to the injection substance, in particular, not soluble thereby, which receptacle can be destroyed easily by initiating the lifting movement. This leads to a dead volume arranged in the ampoule in an always defined manner and which is chemically and mechanically limited with respect to the injection substance without the aid of lifting or plunger means and is only released in the case of a given pressure destruction. For the planned destruction of the receptacle and, at the start of injection, in order to permit the injection substance present in the region of the destroyed container to flow substantially into the cannula inlet opening, optionally in a delayed manner as a result of its immediate entry into a gas-dead-volume space, it is provided advantageously that the needle and/or needle bearing has a formation therein or thereon to come into contact with the receptacle wall and to lead to the destruction of the dead volume receptacle upon pressure application. This formation has, in particular, a pointed cannula end directed onto the receptacle wall, preferably, arranged adjacent thereto, the cannula inlet opening, for the purpose of flowing-in of the injection substance

- 12 occurring upon destruction of the receptacle, being provided, in particular, free of obstruction by jamming, on the formation, especially with an adequately large inlet cross-section and/or remote from the receptacle wall. It is particularly expedient for the receptacle to contain at least one substance which, together with the ampoule contents engaging on the undestroyed receptacle, produces an injection substance to be administered. Thus, it is achieved that the solid, liquid and/or gas in the capsule are held separated from the injection substance, namely a solvent or a liquid injection medium engaging thereon, and are kept ready and that, when the capsule is destroyed in defined manner there is a mixing of liquids or a dissolving of solid and/or gas, so that a resultant injection substance flowing into the cannula opening is produced.

The self-mounting of the needle permits, in a particularly expedient manner, the ampoule to be designed as a receptacle of glass or similar material chemically resistant to the injection substance. As a result of the needle bearing type according to the invention, the ampoule wall is free from unfavourable forces, so that glass can be used advantageously as the material not attacked, e.g. by an atropine sulphate solution.

With a view to a particularly compact construction, a replacement of an ampoule and/or substantially unlimited stability for a large number of injection substances, it is

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- 13 particularly advantageous that the ampoule seal of the glass ampoule is designed as a silicone plate with a beaded tin plate rim, the needle being provided to lie completely in the interior of the ampoule and the plate to be penetrated by the needle. In place of silicone for the plate or tin plate for the beaded edge, it is possible to use other materials, particularly hardened plastics, which are inert with respect to injection substances and which satisfy mechanical and constructional requirements.

A cannula outlet opening provided with an outlet grinding favours, particularly, a rapid penetration of tissue parts having pain receptors and safeguards minimizing of trauma due to high cutting action. Moreover, a defined fluid release to be obtained according to the invention, particularly at low injection solution quantity, effects limited tissue pressure conditions.

In order to make interfaces inert which come into contact with injection fluids, such as the plate seal, the needle and a lifting element, the sealing plate may consist of silicone or a plastic suitable in accordance with the injection substance, the cannula may consist of a V2A or V4A steel bringing about a very good sliding action between the ampoule inner wall and needle bearing, and the ampoule plunger may consist of chlorinated or chlorobutyl caoutchouc or a plastic material depending on the injection substance.

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- 14 Particularly for a simple changeover and for an easy replacement of the ampoule presenting these possibilities and having an integrated needle bearing, an embodiment of the automatic device according to the invention has, as its casing, a jacket casing and a closure cap laterally closing the casing in the region of the ampoule seal and mounting the ampoule. It is particularly appropriate to design the closure cap as a spring catch arrestable by means of groove and tongue means and insertable into the jacket casing.

In an injection device with a pressure device, which comprises a helical compression spring, a spring sleeve and a tappet or piston driving the lifting element as a result of spring pressure, a particularly advantageous embodiment of the device, made possible through the needle bearing according to the invention and the thus resulting construction of the ampoule, consists in that the spring is arranged and kept tensioned between a jacket casing and the spring sleeve, that the spring sleeve is mounted displaceably on the jacket casing and is operatively connected to the piston and that the ampoule guiding and mounting the needle body in sliding fit directly on the inner wall thereof is so arranged that it extends into the positioning area of the tensioned spring, in particular enveloping the ampoule, i.e. to this extent being directly above it. This arrangement leads to a particularly robust, functionally reliable.

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- 15 small injection device ensuring a high spring or driving force and therefore being efficient. Thereby, in particular, it is achieved that only the piston is driven into the ampoule, whilst the spring is separately mounted outside the ampoule between the jacket casing and spring sleeve, even in the case of untensioning thereof, i.e. it comes into action outside the ampoule. The spring sleeve driving the piston ensures a particularly stabilized force action, i.e. a trouble-free, precisely aligned, linear piston drive. The force action and transmission, as well as the spacial arrangement within the device are particularly favourable, because the power source, i.e. the spring, is located in the vicinity of the ampoule lifting element in a space-saving manner on the outside between the jacket casing and the ampoule even in the tensioned state. Thus, the ampoule is mounted in a very shockproof and, therefore, shatterproof manner. Thus, a particularly strong construction or dimensioning of the spring, i.e. a helical spring with a relatively large diameter and thick spring material is possible whilst being tensionable to the smallest space, but the particularly small construction of the overall device is not impaired. The free, independent ampoule needle bearing ensures such a compressed construction safeguarding a high driving force. This is, in particular, achieved in that the jacket casing is designed as a cylindrical, stepped sleeve with a front portion substantially sur16

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- 16 rounding the ampoule and a rear portion following thereafter via a shoulder and having a diameter smaller by the shoulder as compared with the front casing portion, and that the spring sleeve is mounted in the rear casing portion and also on the cylindrically designed ampoule in a movable manner and in the tensioned state of the pressure device, overlaps the same substantially along the extension of the tensioned helical compression spring, the spring being kept tensioned between the shoulder and an annular projection arranged at the overlapping end of the spring sleeve. When the device is in the tensioned state, this structure permits that the tappet of the piston may be arranged to lie upstream of the inner end of the ampoule and outside the latter and that a tappetside ampoule lifting element, particularly a lifting plunger terminates substantially with said end, a second lifting element enclosing a compressible space with the tappet-side lifting element, which, if necessary, is provided on the needle side, and that the piston may be mounted at its rear end on the spring sleeve and may consequently be drivable in the direction of the needle.

It can be seen that the device is advantageously constructed with a spatially outwardly closed ampoule, the force being transferable to the needle-side lifting element via a suitable compressible space. When the device is in the tensioned state, it is also possible for the piston to enter the ampoule and pass through the

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- 17 helical spring, thereby engaging with its tappet on the plunger and being mounted at its other, rear end on the spring sleeve and being consequently drivable in the direction of the needle. The rear, tapered casing portion forms a space-saving, movement-stabilizing sleeve friction bearing for the spring sleeve, little space being required for the helical compression spring and the latter being located in space-saving and space-utilizing manner between casing jacket and ampoule and parallel to the latter, its operation not having any disadvantageous effect through the external arrangement thereof on the spring sleeve, so that, in particular, it is possible to use a per se fragile glass ampoule made possible through the needle bearing type according to the invention.

The needle bearing or ampoule design according to the present invention enable a further development of the invention with a view to a particularly compact as well as sterility-ensuring construction of the device and/or particularly with respect to re-usability of device parts, which development resides in that in a known per se manner the release mechanism may comprise a release sleeve which is axially displaceably arranged on a jacket casing and a release element movable therewith, as well as a spring element connected to the pressure device, arrested on the jacket casing and thereby keeping the pressure device in the tensioned state, the spring element being releasable from its spring seat when the release element

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- 18 strikes against it, and consequently the pressure device being releasable. Thus, the aforementioned subdivision of the jacket casing into a front and a rear portion enables, for the further improvement of the handy and practicable use of the self-injection syringe, that the release sleeve be small, easily operable and displaceably mounted on the rear, offset casing portion, only, in sliding fit in the direction of the shoulder.

In order to avoid any undesired release of the syringe, the device according to the invention may be equipped with a known per se safety device for a particularly reliable and effective operation, which safety device may comprise a safety element with an engagement element engaging on the piston and keeping the same locked against the force of the spring. With regard to easy fitting possibilities and taking account of re-use, it is particularly appropriate for the safety element designed as a safety button to be mounted on a beaded rim frontally designed on the release sleeve and simultaneously forming the release element, and for the engagement element designed as a button pin or plug to engage in the rear end of the piston, which end is designed as the release spring element.

The individual parts of the device according to the invention as well as the latter itself can be inexpensively series-produced. The constructional combination of the parts leads to a particularly safely functioning

- 19 device of short dimension and, ensures the sterility necessary for injection. Inexpensive plastic casing parts can be made impermeable to light, so that even when using advantageous glass ampoules, light protection and therefore long-term storage are safeguarded. A helical compression spring may expediently be designed as a galvanized steel spring, which can, in particular, have a high spring pressure, without impairing the operational or functional reliability of the components and, in particular, of the ampoule. The glass ampoule embodiment leads to an only weak magnetic ampoule or device. In other words, it is not unfavourably influenced in this respect from the ambience.

The advantages attainable according to the invention are, in particular, that an automatic syringe and a cartridge, a phial or ampoule are obtained which, in the case of a construction ensuring sterility and high storage stability, are particularly handy, practical, operationally reliable and efficient, the ampoule enabling defined arrangements of gas or dead volumes, as well as the use of substantially all possibly relevant injection substances and, in particular, such substances which are separated, to be mixed or to be dissolved. Unskilled persons are given the possibility of an almost painless administration of an either subcutaneous or intramuscular self-injection. There is a possibility of a simple changeover and replacement of injection ampoules, together

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- 20 with the re-use of device parts. The needle/ampoule design according to the invention or the material structure attainable therewith for an ampoule, as well as the simple and reliable manner of construction and of operation resulting from the pressure device, release mechanism and safety device enable an almost unlimited life for a large number of injection substances, as well as a particularly safe operation meeting the particular requirements of medical application, the cannula passing out very rapidly so as to ensure freedom from pain and, depending on the positioning of an injector, it can optionally pierce clothing and a few millimetres of skin surface, without any injection fluid emerging when a dead volume is provided, but this is followed by a very rapid and deliberate fluid ejection.

BRIEF DESCRIPTION OF THE DRAWINGS

Other and further objects of the present invention will be apparent from the following description and claims and are illustrated in the accompanying drawings which by way of illustration schematically show preferred embodiments of the present invention and the principles thereof and what now are considered to be the best modes contemplated for applying these principles. Other embodiments of the invention embodying the same or equivalent principles may be used and structural changes may be made as desired by those skilled in the art without departing

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- 21 from the present Invention and the scope of the appended claims. In the drawings

Fig. 1 shows, by way of a side view, a section through an injection device in accordance with the present invention and showing an ampoule in accordance with the invention mounted therein;

Figs. 2 to 4 shows views of injection needles in accordance with the invention;

Figs. 5a and

5b show an ampoule in accordance with the invention with a sterile-manner mounted needle; and

Figs. 6a and

6b show an ampoule in accordance with the invention with a capsule and a floating needle.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

According to Fig. 1, an automatic injection device 1, which is in its tensioned state, comprises a one-piece, cylindrical jacket casing 10 with a front casing portion 101 and a smaller diameter rear casing portion 102 stepped

- 22 with respect to the former by means of a shoulder 103.

The front end of the injection automat 1 is closed by a closure cap 11 mounting an ampoule or phial 2 in accordance with the present invention. This ampoule is inserted in the casing portion 101 and is arrested'with a detachable snap catch having groove and tongue means 110/111. On the rear casing portion 102 there is provided, in a sliding fit, a release sleeve 12 terminally closed by a safety button 13 as a safety element and which is held in the sleeve by means of a recess 123 and by an all-round thickened casing portion 124 on the rear casing portion 102. The latter internally mounts a cylindrical spring sleeve 41 in a sliding fit, which in turn mounts the ampoule 2 in a sliding fit and can move over and beyond the same.

The ampoule or cartridge 2 in accordance with the invention shown in Fig. 1 is designed as a cylindrical glass receptacle, which is sealed to the outside on the front side of the ampoule with a silicone plate 23 comprising a tin plate, beaded rim 231 and with an injection fluid 25, particularly an injection solution of atropine sulphate, acid for pH-value setting, e.g. hydrochloric acid, a suitable salt for isotonization, e.g. sodium chloride and water for injection purposes, between seal 23 and a liquid-sealing lifting plunger 22 as lifting element. Using glass as the material for ampoule 2 ensures, over a long period, that the injection solution is maintained sterile and pyrogen-free, with suitable tonicity and the desired pH-value is maintained, whilst ensuring freedom from impurities according to standard purity criteria. Due to low thermal conductivity of the glass receptacle 2, heat transfer to the injection fluid, which can occur in the case of conventional metal ampoules, is avoided, so that the fluid is protected against decomposition by high temperatures and to this extent is kept stable.

In the case of an injection device according to Fig. 1, the lifting plunger 22, which is slidable in the ampoule 2, is located in the area in front of the inner end 410 of the spring sleeve 41, and the rear end region 24 of ampoule 2 extends into the spring sleeve 41 up to the area of the casing shoulder 103. Outwardly, the plunger 22 engages on a tappet 422 of a piston 42, which, by means of an all-round bead 424 on the rear end 411 of the spring sleeve 41, is mounted in the ampoule 2 to move in the direction of the lifting plunger 22 and to advance the latter.

There is provided a hypodermic or injection needle 3 located completely within the ampoule 2, i.e. located in the fluid 25 between the seal 23 and the lifting plunger 22. The needle is designed as a coiled cannula with two terminal cannula windings 311, 312, which, as winding bodies, form a needle bearing 31, in that the outer faces of the windings directly establish a sliding fit on the ampoule inner wall 21. The outer winding 312 forms a substantially planar abutment for the lifting plunger 22, so that the winding body can be driven forwardly linearly in the direction of its axis or the central axis of the ampoule 2 by means of the lifting plunger 22. With respect to a particularly small construction, and for establishing a bearing for a lifting plunger, it is appropriate to embed the winding body at least partly in the lifting plunger, whilst leaving free the winding’s sliding faces. - The winding 311 passes into an elongated cannula-needle body 30, which is aligned precisely in the ampoule central axis 26. To assist a precisely central alignment and guidance, it is possible to provide a spacer element not impairing a floating mounting of the needle and the free mobility thereof, in particular a spacer disk 27, indicated in broken line form, in the front area of the ampoule. The cannula is open at the end of the winding 312 by means of a cannula inlet opening 34 located on the lifting plunger 22 in the area of the abutment of the needle bearing 31. The needle point is designed as a cannula outlet opening 33 provided with a grinding, which, during the ejection or drive of the needle 3, pierces the seal 23 in axial direction 26. Immediately following the piercing, the fluid 25 is ejected through the cannula 30, 31 provided with the windings 311, 312.

In Fig. 2 a front and a longitudinal view of the hypo25

1295S02 dermic needle 3 inserted in the ampoule according to Fig. 1 are represented. By means of the needle bearing 31, i.e. by the needle body substantially comprising two windings 311 and 312, bearing and sliding surfaces for the ampoule inner wall 21 are formed in the axial direction and transversely thereto on the circumference of the winding body, as can be seen at 313 and 314. The inlet opening 34 is positioned in a protected manner within the winding body 31. The needle bearing in accordance with the invention can as well be provided with a winding body 31, essentially comprising one turn or winding 312, only, as shown in Fig. 3. As shown in Fig. 4, a further embodiment for a needle 3 consists in that a terminal winding 312 is not closed completely, but that there remains an aperture angle of, for example, 300. An exact needle alignment and guidance is ensured with such a reduced winding construction, as well, because the needle body or needle shaft 30, in particular, floats in an injection fluid and is kept centred thereby. The described terminal windings 312 are terminated by a winding surface 315 perpendicularly to the needle axis 26 at the end. With a view to obtaining a particularly short ampoule, it is particularly possible to mount a thin-walled, closed surface element on a terminal turn 312 or to attach it thereto, as is indicated by the hatched area in Fig. 4. Thus, the needle bearing is itself designed as a lifting element or drive-side sealing

1295S02 element, so that there is no need for a separate ampoule plunger.

According to Fig. 1, a pressure device 4 of the automatic injection device 1 comprises a spring sleeve 41, the piston 42 and a helical compression spring 40.

The latter is kept tensioned in a space-saving manner externally on the spring sleeve 41 between the ring projection 410 and the shoulder 103 and thus is arranged between the casing portion 101 and the spring sleeve 41 , in the rear end region 24 of the ampoule 2. This arrangement and space subdivision permit the use of a strongly dimensioned, i.e. a high spring-energy-holding spring.

The pressure device 4 or the spring 40 are tensioned by means of the rear end 423 of the piston 42, in that the end engages as a mushroom-shaped spring element 421 ,· against a terminal opening rim 104 of the casing portion

102.

A release mechanism 5 comprises the release sleeve with a release element constructed as a rim 121 and concentric to the mushroom head of the spring element 421, which rim compresses the mushroom head by striking against the same and consequently sets free the piston spring element 421 or the piston movement due to the force of the spring 40.

A safety device 6 has, as a safety element, the safety button 13 inserted in the rim 121 with a pin or plug 131, which engages in a groove of the mushroom head spring

- 27 element 421, so that it is not compressible with the release element 121 and consequently the spring is reliably arrested in the tensioned state.

The casing components 10, 11, 12 and 13, as well as the ampoule seal 23 are designed as inexpensive, lightimpermeable plastic elements. The glass ampoule 2 with the integrated sliding needle bearing 31 in combination with the snap cap 11 mounting the same, as well as with the arrangement and subdivision of the described components permits the re-use or new use of the device 1, the release sleeve 12 being removable and the locking device 123/124 being detachable, in that the compact ampoule 2, which particularly meets medical requirements, can be substituted simply and the spring 40, designed as a galvanized steel spring, can be re-tensioned rapidly and easily, whereby the components 10, 40, 41 and 42 can consequently be used anew without replacement. The overall construction is short and has a limited weight. This, however, does not impair the robustness of the automatic injector.

The automatic injection device in accordance with the present invention advantageously permits to achieve a liquid ejection quantity of approximately 0.7 g and a cannula exit length (between the cannula tip and the outer wall of the ampoule seal) of approximately 23 mm.

The cannula exit time can, at a spring pressure of approximately 10.5 N/m2, be approximately 0.5 s. The

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- 28 compact structure, in particular, permits an overall length of approximately 103 mm at a diameter of approximately 15 mm. Tests have shown that the ampoule with integrated winding cannula mounting ensures that, in the case of a dead volume provided at the cannula inlet opening during administration, the injection fluid immediately following the releasing of the device initially does not exit from the cannula, but is only ejected after penetrating a few millimetres of skin surface.

Thus, the liquid discharge takes place in a defined and uniform manner and consequently establishes a favourable physiological depot in differing bleeding and tissue structures.

An ampoule, in accordance with the invention and to Fig. 5, comprises an air or gas space 291, in which is held, guided and mounted, in sterile manner, a hypodermic needle 3 with a needle bearing 31 comprising one winding 310. To the space is connected, by means of a lifting-sealing element 29, an ampoule space 292 containing an injection solution 25 and which, on the drive side, is closed by a rubber plunger 22 as the lifting element. As can be taken from Fig. 5a, the plunger 22 comprises a dead volume or an air space 22 when the ampoule is in its non-operative state. Towards the side of the sealing element 29, the needle 3 has a spearshaped formation 35 located in the ampoule axis 26 and comprising an inlet opening 34. Due to the easier compressibility of the gas space 291 as compared with the injection solution space 292, prior to its entry/ passage of the tip 35 into or through the lifting-sealing element 29, the needle 3 is driven in a liquid-free manner through the ampoule seal 23 over a given length and, as shown in Fig. 5, it is only then that there occurs an inflow of liquid into the inlet opening 34 through the cannula. Together with the passage strength of the lifting-sealing element 29, the formation 35, dependent on the degrees of compression and/or volume in the two spaces 291, 292, determines the thus defined delayed liquid discharge.

A cannula, in accordance with the invention and to Fig. 6, comprises a capsule 28 arranged between the injection substance space 293 and lifting plunger 22 and which has a capsule wall 295 chemically resistant to the injection fluid 25. Due to the charging with pressure, the capsule 294 disintegrates (Fig. 6b). This destruction is initiated by a spear-shaped formation 35 having a cannula inlet opening 34. The capsule 294 is at least partly filled with solid, liquid and/or gas 294, two previously separate fluids being mixed or a solid and/or a gas being dissolved in liquid during or after capsule destruction, so that a resultant injection substance is obtained. This substance flows into the inlet opening 34 in a concentration forming in the capsule destruction area and is ejected with the complete ejection of the

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- 30 needle 3. It is, therefore, made possible to inject injection substances or injection components which have been kept separately. The direct arrangement of the formation 35 or the inlet opening 34 on receptacle wall

295, as shown in Fig. 6b, make it possible to ensure a delayed injection substance outlet due to the gas present in the capsule. The cannula winding bearing 31 in accordance with the invention, together with the needle body 30 floating in the injection solution 25 ensures an optimum mounting and guidance of the needle 3.

- 31 1295902