WO2004064902A1

WO2004064902A1 - Device for administering a pre-determinable dose of a liquid product

Info

Publication number: WO2004064902A1
Application number: PCT/CH2004/000027
Authority: WO
Inventors: Fritz Kirchhofer
Original assignee: Tecpharma Licensing Ag
Priority date: 2003-01-21
Filing date: 2004-01-19
Publication date: 2004-08-05
Also published as: DE10302163A1

Abstract

The invention relates to a device for administering a pre-determinable dose of a liquid product, preferably a disposable pen. Said device comprises a container for the product, in which a piston is arranged in such a way that it can be longitudinally displaced in an advancing direction; a sleeve-type mechanism holder; a driven member that can be longitudinally displaced in the mechanism holder and acts on the piston; a drive member that can be displaced in relation to the mechanism holder, in the advancing direction and away from the same, and entrains the driven member during a displacement in the advancing direction; and a dose adjusting mechanism comprising a scale for displaying an actually adjusted dose. The inventive device is characterised in that the mechanism holder comprises a window on the outer periphery thereof. At least one section of the dose scale is located on said window, said section co-operating with a mark coupled to the dose adjusting mechanism, inside the mechanism holder, in order to display the actually adjusted dose.

Description

Device for administering a predetermined dose of a liquid product

The present invention relates to a device for administering a predeterminable dose of a liquid product, preferably a disposable injection pen.

In known disposable pens, as are known, for example, from WO 89/07463 for the injection of insulin, the dose to be administered is usually set with a protective cap. The numbers from 1 to 20 are printed on the protective cap. After removing the protective cap, it is therefore not possible to say with absolute certainty which dose has actually been set. Replacing the protective cap can cause even more uncertainty because the protective cap can be replaced in any desired position.

The other integer multiples of the number 20, i.e. the numbers 20, 40, 60 ..., are printed on a dosing button, so that the dose scale consists of sections that are relatively far apart but can be read together, which makes handling even more difficult. An effective dose setting is actually accomplished by twisting an ampoule sleeve relative to the pen mechanism. When the injection pen is screwed on, the ampoule sleeve can therefore be rotated, which means that the dosage is adjusted and the effective dosage can no longer be checked.

A device according to the preamble of claim 1 is known, for example, from DE 199 00 827 C1 by the applicant. The actually set dose is displayed in accordance with the principle described in WO 97/36 626 by the applicant, according to which a dosing arrow on a mechanical holder with one on one rotatable metering element interacts with the printed dose scale. The reading accuracy is comparatively low. Problems with the reading accuracy occur in particular when larger numbers of dose units that are far in the double-digit dose unit range are to be clearly displayed.

It is an object of the present invention to develop a device of the type described in such a way that even larger dosages can be displayed and set in a simple and reliable manner with simple handling.

This object is achieved by a device with the features of claim 1. Further advantageous embodiments are the subject of the dependent subclaims.

According to the invention, the preferably sleeve-shaped mechanism holder has a viewing window on its outer circumference, in which there is at least a section of the dose scale, the section cooperating with a marking coupled to the dose setting mechanism in the interior of the mechanism holder in order to indicate the actually set dose of the device. The viewing window, which is designed as a recess or integrated on the outer circumference of the mechanism holder, can be closed off by a transparent material to protect the device mechanism.

According to the invention, no additional space needs to be provided for applying a marking which indicates the actually set dose. Rather, an element coupled to the dose setting mechanism, on which the marking is attached, can be used in the interior of the essentially sleeve-shaped mechanism holder. An advantageously space-saving construction of the device according to the invention can thus be realized without the need to provide additional elements.

The marking can be a color field contrasting in color with the other elements, a color marking, for example line or spiral marking. The marking on the for driving the Output element serving drive element or provided on an element coupled thereto, for example on a cam or collar located near the front end of the drive element, which protrudes radially from the outer surface of the drive element, or on a spiral peripheral front edge of a sleeve-shaped metering element serving for metering. The element which is provided with the marking preferably also serves as a stop which is axially adjustable, for example by axial displacement or by turning a threaded rod or the like, in order to limit a maximum stroke of the piston for injection. It is advantageous that the adjustment movement of the element or the stop element can be used automatically for the axial adjustment of the color marking, so that no further elements are required for a dose display.

The dose scale is preferably formed in two parts and comprises a first section which is used to display larger dose units, for example integer multiples of 10 dose units, and a second section which is used to display smaller dose units, for example fractions of the larger dose units, for example 1 unit Dose units with the numbers 1 to 9. According to the invention, at least a section of the dose scale, very preferably the section displaying the large dose units, is arranged at the viewing window, preferably in the axial direction, ie in the direction of advance of the color marking, and along a long side of the viewing window.

The section indicating the smaller dose units is preferably a number which is distributed at equal angular intervals over the outer circumference of a sleeve-shaped, rotatable metering element. For example, the numbers 0 to 9 can be arranged on the front edge along the outer circumference of a metering element. In this embodiment, the adjustment length of the marking corresponds to a scale part of the section indicating the larger dose units, for example the 10-point scales, when the metering member rotates. It is advantageous that even larger dose units can be displayed precisely and clearly with this simple arrangement. Because even with a comparatively small diameter of the metering element, according to the invention the numbers 0 to 9 can be arranged clearly visible along the outer circumference. According to the invention, no higher digits, in particular no integer multiples of the larger dose units, have to be attached to the comparatively small outer circumference. This enables a clear and easy-to-use display of the actually set dose.

Instead of on an outer periphery of a dosing member or the like, the digits of the portion of the dose scale indicating the smaller dose units can also be arranged on the outer periphery of a rotatable element located within the mechanism holder, which lies in the region of the viewing window. It is advantageous that the larger and smaller dose units can be displayed simultaneously and clearly in the area of the viewing window.

Rod-shaped bodies which act axially on the piston in order to propel it towards the product ejection are preferably used as the output member. For a space-saving construction, a drive device is constructed in two parts and comprises a drive member that can be moved in and against the feed direction of the piston and a driven member that can only be moved in the feed direction and locked against the feed direction. For this purpose, the driven member is secured against displacement against the direction of advance of the piston relative to the mechanism holder, for which purpose latching means are provided on the rod body, which cooperate with correspondingly designed latching means which are connected to the mechanism holder. Furthermore, the drive member comprises further correspondingly designed latching means which interact with latching means on the rod body. Mechanical detent means are preferably used as detent means, preferably rows of teeth with sawtooth-shaped tooth flanks or an external thread on the rod body, which makes it possible to transfer the dose adjustment directly to the drive element by rotating a metering element. The drive member itself is preferably sleeve-shaped and essentially surrounds the rod body along its entire length. Preferably, stop means are provided on the outer circumference of the drive member, which have associated stop elements, on the mechanism holder, the housing 'of the device or on these displacement-secured elements are attached, work together to limit a maximum injection stroke of the piston.

Preferred exemplary embodiments of the invention are explained below with reference to the attached figures. Show it:

Fig. 1 shows an injection device according to a first embodiment of the present

Invention in cross section; Figure 1 a shows the cross section A-A of Fig. 1.

2 shows a plan view of the injection device according to FIG. 1 in a zero position and in a metering position; Fig. 3 shows an injection device according to a second embodiment of the present

Invention in cross section; and FIG. 4 shows the injection device according to FIG. 3 in a top view in a zero position and in a metering position with a dose which is actually set and which is different from zero.

In the figures, identical reference symbols designate identical or functionally identical elements and / or assemblies.

1 shows a longitudinal section of an injection device, in the exemplary embodiment an injection pen, according to a first embodiment of the present invention. The injection device 1 has a housing with a front housing sleeve 2 and a rear housing sleeve 7 that can be firmly connected to it, for example screwed on. The front housing sleeve 2 serves as a receptacle for an ampoule 4 serving as a product container. The ampoule 4 contains a liquid product, preferably a solution or suspension containing a therapeutic or medicinal active substance, for example insulin, the product being displaced axially in the ampoule longitudinally displaceable piston 5 is poured out of the outlet opening 3 of the ampoule. For this purpose, a carrier for an injection needle, cannula or the like can be attached, in particular screwed, to the front end of the front housing sleeve 2. The displacement of the piston 5 in the feed direction, ie towards the outlet opening 3, is brought about by a drive device which is accommodated in the rear housing sleeve 7. The drive device comprises as a driven member a threaded rod 6, which acts directly on the piston 5, and a drive member 19. When the dosing button 11 located at the rear end of the injection device 1 is turned, the drive member 19 coupled to the sleeve part 13 is rotated so that it is axially reset on the external thread of the output member 6. The drive member 19 can be displaced in the direction of advance of the piston 5 by axially advancing the dosing button 11 serving as an actuating element. The sleeve part 13 is formed along the sleeve-shaped rear end of the drive member 19 within the rear end of the rear housing sleeve 7 or the peripheral wall of the dosing button 11 The space can be moved lengthways.

The threaded rod 6 serving as an output member is secured against rotation and longitudinally displaceable in the rear housing sleeve 7. A flattening, groove or the like which runs in the axial direction of the threaded rod 6 and which interacts with a guide element (not shown) which has a corresponding cross section is used, for example, to prevent rotation. Axial pulling away, away from the outlet opening 3, of the threaded rod 6 is prevented by the locking means 9, 10 located at the front, sleeve-shaped end 8 of the front housing sleeve 7. In this example, the locking means 9, 10 are latching hooks which engage in the thread of the threaded rod 6. The external thread of the threaded rod 6 has a sequence of sawtooth-shaped flanks pointing in the feed direction and essentially radially inwardly directed edges. As shown in FIG. 1, the locking hooks 9, 10 form an acute angle with the rotational and longitudinal axis L of the thread of the threaded rod 6, which corresponds to the angle of the flank of the external thread of the threaded rod 6. The locking hooks 9, 10 end in the axial direction at different heights, corresponding to the pitch of the external thread. Due to the interaction of the front end of the locking hooks 9, 10 with the rear edge of a respective tooth flank, the driven member 6 is secured against displacement from axial pulling out. However, the locking means 9, 10 do not act on an axial advancement the threaded rod 6 counter. Rather, the elastically designed locking means 9, 10 are bent radially outward when the threaded rod 6 is advanced in order to slide on the tooth flanks. The angular position of the threaded rod 6 and the positions of the front ends of the locking means 9, 10 are coordinated with one another such that the locking means 9, 10 in the zero position shown in the upper part of FIG. 2, in which a vanishing dose is set, or in the case of integers Engage 10-packs (10, 20, 30 ...) completely on the back of the assigned tooth flank.

When the dosing button 11 is rotated counter to the direction of rotation of the external thread of the output member 6, the sleeve-shaped drive member 19 also rotates due to the coupling through the sleeve part 13. Due to the thread engagement by the threaded nut formed by the two drivers 21, 22 at the front end of the drive member 19, the drive member 19 thus moves upward when the metering knob 11 is turned on the thread of the output member 6 and is thus adjusted axially outward. In the embodiment shown in FIG. 1 as a circumferential projection, a cam 20 gradually migrates into the empty space 18 formed with the sleeve-shaped stop element 16 until the axially rear end of the cam 20 has reached the front end of the stop sleeve 16. in which case a maximum administrable dose would be set.

When the user has set the desired dose, which is indicated by the dose scale discussed below, the injection of the liquid contained in the ampoule 4 is effected by axially advancing the metering button 11 serving as an actuating element, which, due to the coupling through the sleeve part 13, ensures the rotationally fixed Drive member 19 axially advances.

In the zero position shown in FIG. 1, the front end of the cam 20 bears against the stop formed by the radial gradation of the front end 8 of the rear housing sleeve 7, so that neither the drive member 19 nor the driven member 6 coupled thereto are further advanced axially can. Starting from this zero position arises when turning the dosing knob 11 and the resultant axially resetting the drive member 19 a clear metering distance between the front end of the cam 20 and the rear of the front end 8 of the rear housing sleeve 7. This clear metering distance, not shown, corresponds unambiguously to the number of revolutions of the metering member 11, which via the threaded engagement of the drive member 19 with the Output member 6 is converted into an axial adjustment movement of the cam 20.

Arranged in the outer peripheral surface of the rear housing sleeve 7 is the rectangular viewing window 17 shown in plan view in FIG. 2, in which, for example, a plate made of a transparent plastic can be inserted, which provides a view of the interior of the rear housing sleeve 7 located underneath. The viewing window 17 can also be formed in the original molding process, for example in two-component injection molding from an opaque plastic component and a transparent one for the viewing window. In the zero position of the injection device shown in FIG. 1, i.e. when the dose actually set disappears, the rear end of the cam 20 is aligned with the front end of the viewing window 17 or with a zero marking provided on the viewing window 17 (not shown). Alternatively, a marking (not shown) arranged on the outer peripheral surface of the drive member 19 in the region of the viewing window 17 can be aligned with the front end of the viewing window 17 or the aforementioned zero marking. In this way, the user is shown the zero position of the dosing device.

As can be seen from FIG. 1, the cam 20 or the aforementioned mark provided on the outer circumferential surface of the drive member 19 moves further and further into the viewing window 17 when the drive member 19 is axially reset. According to the invention, this is used to display the actually set dose. For this purpose, the outer peripheral surface of the cam 20 and the outer peripheral surface of the drive member 19 form a clearly perceptible color contrast in the region of the viewing window 17 behind the cam 20. For example, the outer peripheral surface of the drive member 19 has the same color as the outer peripheral surface of the rear housing sleeve 7 and the outer peripheral surface of the cam 20 forms a color contrast. In the axial Resetting the drive member 19 thus moves according to the invention a color pattern with a perceptible contrast, for example black and white, into the viewing window 17, as can be seen in FIG. 2.

As shown in FIG. 2, a 10-scale 25 divided into integer multiples of the number 10 is formed in the longitudinal direction on the outer edge of the viewing window 17. This 10-point scale forms a section of the dose scale formed in total from the 10-point scale 25 and the 1-point scale 24. As shown in FIG. 2, the 1-scale 24 has a total of 10 markings formed at uniform angular intervals on the outer circumference at the front end 12 of the metering button 11, for example the numbers 0 to 9. When the metering button 11 is rotated, that is reversed 1-scale back to its old angular position. When the dosing button 11 is turned, on the other hand, the color marking shown in black in FIG. 2 on the outer circumference of the cam 20 moves by the numerical value 10 on the 10th scale 25. Thus, the 10th scale 25 acts with the one coupled with the dosing button 11 Mark on the outer peripheral surface of the cam 20 together to indicate the actually set dose. More precisely, the dose actually set is made up of the integer multiples of the number 10 read on the 10-scale 25 and the numerical value read on the 1-scale 24. Even with a small diameter of the rear housing sleeve 7, numbers that are sufficiently legible and range from 0 to 9 can be affixed to the outer peripheral surface of the front end 12 of the metering button 11. Thus, according to the invention, larger cans can also be set so that they are easy to read.

Alternatively, the numbers on the first scale 24 can also be arranged directly on the outer circumferential surface of the drive member 19 in the region of the viewing window 17 and / or on the outer circumferential surface of the cam 20 with sufficient contrast to the background. In such an alternative embodiment, the numerical values from 0 to 9 would be arranged in a spiral on said outer peripheral surface at uniform angular distances. For dosing and administering a dose, the procedure according to the first embodiment is as follows:

First, the injection device is brought into the zero position shown in FIG. 1 and in the upper part of FIG. 2, where a further axial advancement of the output member 6 towards the outlet opening 3 due to the abutment of the front end of the cam 20 at the rear end of the circumferential projection 8 is reliably prevented. Starting from this zero position, no product can be poured out of the ampoule 4 without renewed dosing. As shown in FIG. 2, the color marking on the outer circumferential surface of the cam 20 has moved out of the viewing window 17 in the zero position and shows the marking arrow 26 for the numerical value “0” on the first scale 24 at the front end of the operating button 11.

To adjust the dose, the dosing button 11 is turned so that the cam 20 is axially reset due to the thread engagement at the front end of the drive member 19 into the external thread of the output member 6. The color marking on the outer circumferential surface of the cam 20 gradually moves into the viewing window 17. At the same time, the metering button 11 is moved back by the axially measured, clear metering distance X and gives a clear view of a stop 15 of the rear housing sleeve 7. The user can adjust the actually set one Read off the dose at any time by reading the 1 scale 24 and the 10 scale 25. If the user has accidentally set a dose that is too large, he can reduce it again by turning back the dosing button 11, unless a locking means, not shown, prevents turning back of the dosing button 11 in a still further embodiment.

After setting the correct dose, the user sticks the injection needle (not shown) into the body tissue. By axially advancing the dosing button 11 serving as an actuating element towards the outlet opening 3, the injection takes place until the zero position is finally reached again. For renewed use, it should be noted that the numerical value of the 1-scale 24 can fundamentally differ from zero. Therefore, the user must first turn the 1-scale 24 to the numerical value zero before a new dosage and when the injection needle is not inserted. So that no relative movement between the drive member 19 and the driven member 6 takes place due to the zeroing movement comparable to the dose selection movement, the dosing button 11 and the sleeve part 13 are connected to one another in such a way that the dose can be selected on the one hand by means of the dosing button 11, but on the other hand a relative rotation can take place between the dosing button 11 and the sleeve part 13 for the purpose of zeroing. For this purpose, a slip clutch is formed between the dosing button 11 and the sleeve part 13 in such a way that the dosing button 11 and the sleeve part 13 carry out the dosing rotary movement for the dose selection together, but a relative rotary movement between the dosing button 11 and the sleeve part 13 is possible for the zeroing when the drive member is in its axially foremost position, in which it is against the housing sleeve 7 on the stop. The slip clutch is soft enough so that there is no kinking of the locking means 9 and 10 and tilting of the drivers 21 and 22 during zeroing. Alternatively, although less preferred, the slipping clutch can be formed between the sleeve part 13 and the drive member 19. In a simplified embodiment, the dosing button 11 and the sleeve part 13 are not decoupled from one another, ie no slip clutch is provided. However, in the event of a zeroing, the injection device must then be moved into the zero position shown by axially advancing the dosing button 11 in order to be able to reliably set a new dose.

In a further alternative embodiment, the sleeve-shaped metering button 11 can be pulled out of the injection device 1 relative to the sleeve part 13 or the sleeve-shaped stop element 16 while maintaining its angular position. In this case, latching means pressing against the inner circumference of the dosing button 11 radially advance on the outer circumferential surface of the sleeve 13. When the dosing button 11 is pushed back axially, the sleeve part 13 or sleeve-shaped stop element 16 coupled to the drive member 19 is then axially advanced. When the cam 20 stops again to reach the zero position, the above-mentioned ones Latching means released, so that the dosing button 11 can completely return to its starting position.

3 and 4 show a second embodiment of the present invention in a longitudinal section and in a plan view. The injection device according to the second embodiment is known in principle from the applicant's patent specification DE 199 00 827 C1, the content of which is hereby expressly included in the present application by way of reference. In the second embodiment, a toothed rack 27 serves as the output member. The toothed rack 27 is formed by a rod body which is rectangular in cross section and which is provided with a row of saw teeth on all four sides in a region at the front with respect to the feed direction. In FIG. 3, two rows of teeth formed on opposite sides of the toothed rack 27, the blocking means 9, 10, are designated by 34 and 35. In addition to the two rows of teeth 34 and 35, the toothed rack 27 has two further saw tooth rows formed on opposite side surfaces of the toothed rack 27, one of which is designated by reference number 36 in FIG. The teeth of the row of teeth 34 to 36 are sawtooth-shaped and have a flat tooth flank that slopes in the feed direction and a rear side that extends essentially radially inwards. The locking means 21 and 22 designed as locking lugs are, as shown in FIG. 3, formed at different heights in the axial direction. When fully engaged, the blocking means 21, 22 engage completely in the tooth of the respective row of teeth that is next to the back of a first tooth and a tooth flank opposite to the direction of advance.

The four rows of teeth have the same tooth pitch. They are arranged within a tooth pitch in relation to each other in an offset with respect to the feed direction, as is disclosed in detail in the applicant's referenced DE 199 00 827 C1. Correspondingly, the locking means 21, 22 or 9, 10 and two further locking means (not shown), which cooperate with the respectively facing further rows of teeth, are at the same height with respect to the feed direction at 90 ° angular intervals. Because of the tooth row offset, only one of the locking means engages with a deepest tooth engagement in a tooth gap of the one facing it Row of teeth when the rack 27 is moved. The three other locking means are each flanks of teeth of the rows of teeth facing them, so that these other locking means are elastically bent away from the rack 27. When the rack 27 is displaced in the feed direction, the locking means 9, 10 successively come into the deepest possible engagement with the row of teeth facing them; overall there is an alternating engagement of the locking means, as described in detail in the aforementioned DE 199 00 827 C1. The locking means 9, 10, which is elastically fully snapped into a tooth base or towards a tooth base, locks the toothed rack 27 against displacement against the feed direction.

According to the second embodiment, the drive device comprises, as the output member, the toothed rack 27, which acts directly on the piston 5, and the drive member 19, which is provided with locking means 21, 22, comparable to the locking means 9, 10 above. The drive member 19 is mounted in the rear housing sleeve 7 in and against the direction of advance of the piston 5 so as to be straight. A cover 38, which is connected to the drive member 19 so that it cannot move, protrudes out of the housing of the injection device 1 to the rear.

A metering element 30 designed as a sleeve body is secured against displacement with the rear housing sleeve 7, for example due to the latching connection shown, but is rotatably connected about the common longitudinal axis. By turning the dosing member 30, the maximum dose path length that can be covered in the feed direction by the drive member 19 and the rack 27 is set, and thus also the maximum product dose that can be dispensed during an injection. For this purpose, a front sleeve part 31 of the dosing member 30 is formed in a spiral circumferential manner on its front end face, ie the front sleeve part 31 progressively drops in a circumferential direction from a foremost end face section with respect to the longitudinal axis of the injection device 1. The dosing member 30 can in principle also be designed in a step-like manner in accordance with a dosing member described in WO 97/36 625 and cooperate with the drive member 19 in the dosing as described there. The metering takes place in the zero position shown in FIG. 3 and in the upper part of FIG. 4, ie, in the foremost position of the drive member 19 in relation to the feed direction, in which a radially protruding from the outer surface of the drive member 19 Collar or cam 29 abuts a stop formed by the rear housing sleeve 7. In this zero position, the dose scale described below with reference to FIG. 4 shows the numerical value zero. In this foremost position of the drive member 19, the metering member 30 is rotated relative to the rear housing sleeve 7 until it has reached the desired metering position. In this metering position, a clear metering distance remains between a further collar or cam 33, which also projects from the outer circumferential surface of the drive member 19, and the end face of the metering member 30 opposite these cams 33. At this metering distance, the drive member 19 can be withdrawn relative to the rear housing sleeve 7 and thus also relative to the piston 5 against the feed direction for product distribution. The withdrawal is carried out manually by axially pulling the cover 25 out of the injection device 1. The dosing distance is equal to the dose path length in the subsequent product administration.

When the drive member 19 is pushed back or pulled back, the toothed rack 27 remains in its displacement position previously assumed during the dosing process, relative to the housing, i.e., with proper operation, in the zero position shown in FIG. 3. The rack 27 is secured against displacement against the feed direction by locking means 9, 10 formed on the rear housing sleeve 7. The locking means 9, 10 are locking cams, which are each formed at a front end of an elastically flexible tongue and protrude radially inward from the tongue onto the rack 27. The locking means 9, 10 each interact with one of the toothed rows of the rack 27 facing them, as described above, in such a way that they allow the rack 27 to be displaced in the feed direction and prevent a displacement against the feed direction by positive locking engagement.

3 shows the injection device in an initial position or zero position in which the rack 27 assumes its rearmost position relative to the rear housing sleeve 7 and also relative to the drive member 19. In this Starting position, the rear housing sleeve 7 is supplied completely assembled by the manufacturer with a toothed rack 27 and drive member 19 including cover 38 and metering member 30. The starting position thus corresponds to the storage position of the injection device, in particular the drive and metering device of the injection device. In the exemplary embodiment, the injection device is a disposable pen. Reusability, ie replacement of the ampoule 4, can, however, be achieved with simple modifications.

In the zero position of the injection device with the ampoule 4 inserted, the product dose to be administered with the first injection is set by the user. For this purpose, the metering member 30 is rotated into a certain rotational position, which corresponds to the desired product dose. In this rotational position, the cam 33 of the drive member 19 has a clear metering distance from the front end face of the metering member 30 opposite it. Only the locking means 9 is in the zero position on a tooth back of the row of teeth 34 on the locking stop. This also applies to the driver 21. The other locking means and drivers are not completely in locking engagement with the assigned row of teeth.

The drive member 19 is pulled out of its foremost position with respect to the rear housing sleeve 7 against the feed direction by pulling the cover 38 out of the injection device 1. When the drive member 19 is retracted, its drivers 21, 22 slide over the tooth rows 34, 35 of the rack 27 facing them. The rack 27 itself remains stationary since it is prevented from being taken along by the locking means 9 against the direction of advance. The cover 38 and the drive member 19 coupled with it so that it cannot move are pulled out of the injection device 1 until the cam 33 comes to rest on the opposite front end face of the metering member 30. This tactile resistance is the signal to the user that the injection device 1 is charged and ready for injection.

During the injection, the drive member 19 and thus also the rack 27 are shifted in the feed direction by pressing against the cover 38 by the preselected dose path length. The rack 27 presses the piston 5 in the ampoule 4 on the Outlet 3 closed and product is poured out. The distribution takes place until the collar or cam 29 protruding from the outer surface of the drive member 19 comes to a stop on the radially inward projection of the rear housing sleeve 7. In this front position, one of the locking means 9, 10 again engages completely in a tooth gap of the associated tooth rows 34 to 36 of the rack 27.

In an alternative embodiment, the locking means and drivers can all be arranged at the same height with respect to the direction of advance, which is described in detail in DE 199 00 827 C1 by the applicant.

FIG. 4 shows the injection device according to the second embodiment in a schematic plan view in two different dose positions, namely when 5 dose units are selected (upper part of FIG. 4) and when 37 dose units are selected (lower part of FIG. 4). A viewing window 17 is provided in the outer lateral surface of the rear housing sleeve 7 serving as a mechanism holder, which provides a view into the interior of the rear housing sleeve 7. In the viewing window 17 there is preferably a window made of a transparent material, in particular plastic. The spirally encircling front end face 32 of the front sleeve part 31 is clearly visible, which forms a line running obliquely to the viewing window 17 in the viewing window 17 in every rotational position of the metering member 30. A suitable color marking can be provided on the spirally encircling front end surface 32, for example a color line with sufficient color contrast. In the exemplary embodiment shown in FIG. 4, the front sleeve part 31 is colored in a clearly perceptible contrast to the rest of the metering element 30, so that the colored area 40 can be clearly perceived by the user. These aforementioned color markings, which are coupled to the metering element 30 acting as a dose setting mechanism, interact with the dose scale as follows:

Along the long side of the essentially rectangular viewing window 17, the 10-scale 25 shown is provided, which shows how many tens dose units are preselected. The scale of 10 forms the first part of the dose scale, which is also the 1-scale 24 comprises at the front end of the metering element 30. The numbers on the 1-scale 24 (numbers 0 to 9) are preferably distributed at uniform angular intervals along the outer circumference of the metering element 30. The 1-scale 24 is in turn formed by a plurality of 1-scale, which follow one another along the outer circumference of the metering element 30. The several 1-scale scales of the scale 24 are each formed identically, each of these scales indicating the single dose units from 0 to 9. The number of several 1-scale scales on scale 24 corresponds to the number of the maximum selectable 10-dose units. In the second embodiment, in which a total of 40 dose units, ie four tens dose units form the maximum dose, the 1-scale 24 therefore consists of a total of four 1-scale scales arranged along the circumference. Thus, the 1-scale 24 periodically displays the same numerical value in the range from 0 to 9 for each quarter turn of the metering element 30. The number on the 1-scale 24 corresponding to the set dose unit per decade is indicated by the marking arrow 26 at the rear end of the rear housing sleeve 7. The actually set dose can be read clearly and reliably from the 1-scale 24 and the 10-scale 25. Because of the formation of the 1-scale 24 from a plurality of individual scales, the dose decades could, for example, be formed axially next to the 1-scale 24 on the metering element 30. However, the display by means of the viewing window 17 and the marking in the form of the end face 32 or a marking of the metering member 30 which can be read through the viewing window 17 improves the reading, at least in terms of uniqueness. As a result, the risk of incorrect dosing due to a misinterpretation of the displayed dose amount is reduced. The numbers on the 1-scale 24 can alternatively also be shown on the outer circumferential surface of the front sleeve part 31 in the area of the color marking 40 (with a color contrast to this) or in the area of the front sleeve part 31 contrasting in color (white in the lower part of FIG. 4) ) can be arranged, preferably also at uniform angular distances over an angular range of 360 °. In such an alternative embodiment, the numbers on the 1 scale 24 revolve in a spiral on the front sleeve part 31.

In the starting position shown in FIG. 3, the numerical value of the 10th scale 25 is automatically within the range from 0 to 10. Depending on the previously selected dose a value other than zero is displayed on the 1-scale 24. To set a new dose, the 1-scale 24 is turned back to zero by rotating the metering element 30 before an injection. After loading the injection device by pulling out the cover 38 and advancing the cover 38 and the toothed rack 27 coupled therewith, the residual dose that may be produced is expelled. The injection device 1 is then in the zero position, in which the next dose to be administered is set as follows.

To set the dose, the metering member 30 is rotated. The numerals of the 1 st scale 24 run past the marking arrow 26 and the spirally encircling front end face 32 of the front sleeve part 31 gradually moves into the viewing window 17. Finally, the desired dose is reached on the dose scales 24, 25.

Subsequently, the injection device is pulled out of the injection device 1 by pulling out the cover 38 and the drive member 19 coupled with it so that it is secured against displacement, until the cam 33 comes to rest on the end face of the metering member 30 opposite it. The user then sticks the injection needle into the body tissue and administers the set dose by advancing the cover 38, which during the advancement advances the drive member 19 and the rack 27 which is in locking engagement therewith and the piston 5 by the set dose path length. After turning the one-scale 24 back or further to the numerical value zero, the aforementioned zero position is reached again, in which a new dose to be administered can be set again.

The color marking on the front sleeve part 31 can alternatively also be formed spirally itself.

An injection device according to the invention is preferably constructed from plastic parts produced by injection molding and is preferably used for diabetes treatment by injecting preselected doses of insulin into the subcutaneous fatty tissue of a patient. In principle, however, any other liquid substances, in particular those containing a medicinal or therapeutic agent are administered. When administering insulin, a Gauge 31 or Gauge 30 injection needle is preferably placed on the front end of the front housing sleeve 2.

Claims

claims

A device for administering a predeterminable dose of a liquid product from a container (2) for the product by axially advancing a piston (5) which can be displaced longitudinally in the container, the device comprising: a sleeve-shaped mechanical holder (7), one in the mechanical holder (7 ) longitudinally displaceable output member (6; 27) on the

Plunger (5) acts, a drive member (19) which is adjustable in and against the feed direction of the piston (5) relative to the mechanical holder (7) and which drives the driven member (6; 27) when displaced in the feed direction, and a dose setting mechanism (11 ; 38) with a dose scale (24, 25) for displaying an actually set dose, characterized in that the mechanism holder (7) on its outer circumference

Viewing window (17), in which at least a section (25) of the

Dose scale is located, which with a coupled with the dose setting mechanism

Marking (20; 32; 40) inside the mechanism holder (7) interacts to indicate the actually set dose.

2. Device according to claim 1, wherein the viewing window (17) has at least one longitudinal side which extends at an angle of less than 90 ° to the feed direction, preferably along the feed direction.

3. Apparatus according to claim 1 or 2, wherein the portion of the dose scale of one

Tens scale (25) along the long side of the viewing window (17) is formed.

4. Device according to one of the preceding claims, in which another section of the dose scale is formed by a one-scale (24), the numbers of which are distributed at uniform angular intervals over a front circumferential edge of a rotatable metering element (12; 30).

5. Device according to one of the preceding claims, wherein the

Dose setting mechanism comprises a rotatable element (19, 20; 31) located inside the mechanism holder (7), which is coupled in a rotationally secured manner to a rotatable dosing member (12; 30) of the dose setting mechanism.

6. The device according to claim 5, wherein the rotatable element forms an axially adjustable stop which limits a maximum stroke of the output member (6; 27) of the device for adjusting the dose.

7. The device according to claim 5 or 6, wherein a one's scale on the with

Dosing member (12; 30) coupled in a rotationally fixed, rotatable element (19, 20; 31) is applied inside the mechanism holder (7).

8. The apparatus of claim 7, wherein the digits of the ones scale under uniform

Angular distances and spirally distributed around the outer circumference of the rotatable element (19, 20; 31).

9. Device according to one of the preceding claims, wherein the rotatable

Element is a cam (20) protruding from the outer circumference of the drive member (19).

10. The device according to claim 9, wherein the output member is an externally threaded rod body (6), wherein on the cam (20) elastically deformable drivers (21, 22) are formed, which in a longitudinal engagement of the drive member in the feed direction in a locking engagement with the output link stand to take the driven member (6) and release the locking engagement with a longitudinal displacement of the drive member (19) against the feed direction.

11. The device according to claim 9 or 10, wherein a front edge of the viewing window (17) in a zero position of the device with a rear edge of the cam (20) is substantially aligned.

12. The apparatus of claim 9, wherein the output member is a rack (27) in which at a front end of the drive member (19) with rows of teeth (34-36) of the rack cooperating drivers (21, 22) are formed and in which at a front end of the mechanism holder (7) with the rows of teeth of the rack interacting locking means (9, 10) are formed.

13. The apparatus of claim 12, wherein the rotatable member (30) at its front end has a spirally circumferential end face (32) on its outer periphery, which forms an axially adjustable stop to limit the maximum stroke of the output member (27).

14. The apparatus of claim 13, wherein the spirally circumferential end face (32) on its outer circumference has a color marking (40) which interacts with the dose scale.

15. The device according to any one of claims 12 to 14, further comprising a sleeve-shaped actuating element (38) connected to the drive member (19) and secured against displacement at its rear end.

16. Device according to one of the preceding claims, which has a Gauge 30 injection needle or Gauge 31 injection needle at a front end for injecting the liquid product.