Patent Publication Number: US-2009221973-A1

Title: Administering apparatus with a resettable activating block

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 11/023,297 filed Dec. 27, 2004, issued as U.S. Pat. No. 7,500,966 on Mar. 10, 2009, which is a continuation of International Patent Application No. PCT/CH2003/000420, filed on Jun. 25, 2003, which claims priority to German Application No. DE 102 29 122 A1, filed on Jun. 28, 2002, the contents of which are incorporated in their entirety by reference herein. 
    
    
     BACKGROUND 
     The present invention relates to devices and methods for delivering or administering substances and, more particularly, to an administering apparatus for administering an injectable substance or product in selected amounts or doses. The administering apparatus can, in particular, be an injection apparatus, for example an injection pen, such as may be used in many different therapies, for example in diabetes therapy or in administering growth hormone. 
     Administering apparatus, for example, injection pens, which allow a product or substance dosage to be administered to be selected typically comprise a so-called dosing mechanism which protrudes from a casing opening of the administering apparatus. The dosing mechanism may be button-like, generally similar to the activating button of a ballpoint pen. In order to prepare for the delivery or administration of a substance, the product dosage may be selected by rotating the dosing button relative to the casing. The rotational dosing movement pre-sets a conveying means. For administering, the dosing button is then pressed, from its dosage selection position, a little way into the casing, as far as a front end position. This activates the pre-set conveying means. The conveying means acts on the product or substance contained in a reservoir of the administering apparatus and conveys the selected product dosage, i.e., the product dosage is delivered from the reservoir. In the front end position, the dosing mechanism is blocked against a reverse movement. After the blocking engagement is released, the dosing button is automatically moved back to the dosage selection position and the administering apparatus is ready to administer another dose and, as applicable in some devices, also to select the dosage anew. 
     Administering apparatus of the type cited above are known, for example, from WO 99/03522 and EP 0 897 728 A1. In the this type of device, however, in order to increase dosing reliability, the reverse movement of the dosing button back to the dosage selection position is only possible if, in the front end position of the dosing button, a dosage indicator of the administering apparatus has been reset to “zero”. In these apparatus, the dosage is indicated mechanically with the aid of a dosage indicator sleeve. During the dosing movement of the dosing button, the dosage indicator sleeve is also moved relative to the casing. The position of the dosage indicator sleeve relative to the casing is used to indicate the selected product dosage. In the administering apparatus of EP 0 897 728 A1, two dosage indicator sleeve are required for indicating the selected product dosage, namely, one dosage indicator sleeve for indicating individual dosage units and another dosage indicator sleeve for indicating the dosage units in increments of ten. 
     In order to reset the dosing button after the product dosage has been administered, the administering apparatus of WO 99/03522 requires two hand operations to be performed: one in order to move the dosage indicator sleeve back to its zero-dosage position and, two, to release a blocking engagement which can only be released in the zero-dosage position of the dosage indicator sleeve. In the administering apparatus of EP 0 897 728 A1, the dosing button is automatically moved back or reset after the two dosage indicator sleeves have been moved back to their zero-dosage position. For the dosing button to be automatically reset by resetting the dosage indicator alone, the dosage indicator sleeve of the two dosage indicator sleeves, which indicate the dosage in increments of ten (the decimal dosage indicator sleeve), is provided with an axial groove. This decimal dosage indicator sleeve surrounds a blocking member which comprises a spring-elastic tongue which is pressed radially inwards by the decimal dosage indicator sleeve into a blocking engagement in which the spring-elastic tongue blocks the resetting movement of the dosing button. If, however, the decimal dosage indicator sleeve is moved to the zero-dosage position, then its axial groove overlaps the spring tongue of the blocking member and the spring tongue can pre-latch radially outwards into the axial groove of the decimal dosage indicator sleeve due to its inherent elasticity force. This pre-latching releases the blocking engagement and the dosing button is automatically moved back to its dosage selection position, driven by the spring force. This resetting mechanism may be susceptible to faults. 
     SUMMARY 
     It is an object of the invention to provide a resetting mechanism for resetting a dosing button—or more generally, a dosing and activating means—of an administering apparatus, the resetting mechanism being simple and not susceptible to faults, i.e., accurate and durable or robust. 
     In one embodiment, the present invention comprises an administering apparatus for administering a substance in selected doses, wherein the apparatus includes a casing with a reservoir for the substance, a conveying mechanism which acts on the substance to deliver a selected dose of the substance from the reservoir, a dosing and activating mechanism which performs a dosing movement for selecting a dose in a dose selection position and a delivery movement in an activating direction as far as a front end position for delivering the selected dose, and which is coupled to the conveying mechanism such that the delivery movement causes the selected dose to be delivered, a dosage indicator sleeve coupled to the dosing and activating mechanism such that the dosage indicator sleeve is moved relative to the casing by the dosing movement of the dosing and activating mechanism to indicate the selected dose, and a blocking member movable into a blocking engagement with the dosing and activating mechanism in the front end position to prevent the dosing and activating mechanism from moving counter to the activating direction, wherein the blocking member can be moved out of the blocking engagement against an elasticity force and wherein a reset cam protrudes from the dosage indicator sleeve, via which the dosage indicator sleeve moves the blocking member out of the blocking engagement when the dosage indicator sleeve is moved to a zero-dosage position relative to the casing. 
     In one embodiment, the present invention relates to an administering apparatus or device for administering an injectable product in doses comprising a casing with a reservoir for the product, a conveying means, a dosing and activating means, at least one dosage indicator sleeve and at least one blocking member for blocking or locking the dosing and activating means after the product has been delivered. 
     The conveying means serves to deliver a previously selected product dosage from the reservoir and correspondingly acts on the product situated in the reservoir. In principle, the conveying means can be formed by any type of pump. In some preferred embodiments, however, a piston arranged in the reservoir and a piston rod form the conveying means. The piston and the piston rod can be moved in an advancing direction to deliver the selected product dosage through the outlet of the reservoir by advancing the piston towards the outlet. The piston and the piston rod can be fixedly connected to each other, but in some preferred embodiments the piston rod contacts or presses loosely against the rear side of the piston and, during the dosage selection procedure, exhibits a slight distance from the piston. 
     In some embodiments, the dosing and activating means comprises a dosing and activating button and a transfer means which is coupled to the dosing and activating button on the input side with respect to selecting the dosage and activating, and on the output side forms the coupling with the conveying means. The dosing and activating button and the transfer means can be formed in one piece. Forming them in multiple pieces is preferred in some embodiments, wherein the multiple pieces may be connected rigidly to each other with respect to the dosing movement. 
     In some embodiments, the product dosage to be administered is selected using the dosing and activating means and delivered by activating the dosing and activating button. Correspondingly, the dosing and activating means can perform a dosing movement relative to the casing for selecting the product dosage in a dosage selection position, and can perform a delivery movement from the dosage selection position in an activating direction as far as a front end position, for delivering the selected product dosage. In some embodiments, the activating direction is the same as the advancing direction of the piston rod, though this is not required. The dosing and activating means is coupled to the conveying means such that delivery movement of the dosing and activating means causes the selected product dosage to be delivered by the conveying means. In one preferred embodiment of the conveying means, in which a displacing piston and a piston rod completely or partially form the conveying means, the dosing and activating means is coupled to the piston rod, for example by threaded engagement, directly or via a transfer element. Selecting a dosage is no longer possible in the front end position, either because the dosing and activating means is no longer accessible for the user in a suitable way for selecting the dosage, because it is decoupled from the conveying means in the front end position, or because it is no longer accessible and is decoupled. 
     In some embodiments, the dosage indicator sleeve is coupled to the dosing and activating means such that it is moved relative to the casing by the dosing movement of the dosing and activating means to indicate the selected product dosage. In some embodiments, a pointer indicates the selected product dosage on a dosage scale. In some embodiments, the dosage indicator sleeve is provided with the dosage scale, while the pointer is formed by the casing. In principle, however, the reverse arrangement is also conceivable. 
     In some embodiments, in order to block the dosing and activating means the blocking member is in a blocking engagement with the dosing and activating means in the latter&#39;s front end position, to prevent a resetting movement of the dosing and activating means, i.e., a movement by the dosing and activating means from the front end position counter to the activating direction. In some embodiments, the blocking engagement is configured such that the resetting movement can only be performed when the dosage indicator sleeve assumes the zero-dosage position, i.e., when it assumes, of its positions relative to the casing, the position corresponding to a zero-dosage. In some preferred embodiments, the blocking engagement is formed between the blocking member and the dosing and activating button directly. However, the blocking engagement can also be formed between the blocking member and the transfer means which couples the dosing and activating button to the conveying means. 
     In accordance with the present invention, in some embodiments, the blocking member can be moved out of the blocking engagement against an elasticity force, which conversely means that the elasticity force causes the blocking member to move into the blocking engagement. A cam protrudes from the dosage indicator sleeve, via which the dosage indicator sleeve presses the blocking member out of the blocking engagement when the dosage indicator sleeve is moved to the zero-dosage position. Since the blocking engagement is released by the cam of the dosage indicator sleeve, thus enabling the dosing and activating means to be automatically reset, this cam may be referred to in the following as a reset cam. 
     Releasing the blocking engagement by means of the reset cam is advantageous with regard to the inevitable production tolerances in the manufacture of the parts of administering apparatus, since the demands on the precision of positioning and forming the reset cam are significantly lower than for a groove into which the blocking member is to pre-latch, as in the administering apparatus of EP 0 897 728 A1. The present invention has the additional advantage that in the zero-dosage position of the dosage indicator sleeve, the positive lock provided by the reset cam prevents the blocking member from persisting in the blocking engagement. The device and method of the present invention is, therefore, not reliant on elasticity forces for releasing. 
     In some embodiments, the reset cam extends only far enough in the direction or directions in which the dosage indicator sleeve can be moved so that the blocking member is definitely free from the reset cam when the dosage indicator sleeve assumes the nearest settable dosage position to the zero-dosage position, relative to the casing. In some embodiments, the dosage indicator sleeve is preferably secured against moving from larger dosage positions beyond the zero-dosage position. 
     In some embodiments, the dosage indicator sleeve and the blocking member preferably surround each other, i.e., at least one of said two parts is sleeve-shaped or comprises a sleeve portion. In one preferred embodiment, the dosage indicator sleeve surrounds the blocking member. In this embodiment, the reset cam preferably protrudes from an inner surface area of the dosage indicator sleeve towards the blocking member. 
     In some embodiments, the reset cam may be continuously widened on at least one side via which it leads onto the blocking member when the dosage indicator sleeve moves to the zero-dosage position, as far as the surface area of the dosage indicator sleeve from which it protrudes, in order that the blocking member and the reset cam slide off of each other in the manner of oblique planes during this movement. In one preferred embodiment, in which the movement of the dosage indicator sleeve is or comprises a rotational movement, the reset cam is widened in the circumferential direction towards the surface area. If the movement of the dosage indicator sleeve is a superimposed movement consisting of a rotational movement and a translational movement, the reset cam can advantageously also be widened towards its foot region in the translational direction towards the side via which it leads onto the blocking member in the direction of the translational movement. 
     In a preferred embodiment, the blocking member forms a counter reset cam, against which the reset cam presses in the zero-dosage position of the dosage indicator sleeve, in order to release the blocking engagement. The counter reset cam may also be tapered towards its free end facing the reset cam, on the side via first comes into contact with the reset cam when the dosage indicator sleeve moves to the zero-dosage position, i.e., the counter reset cam may also be gradually widened towards its foot region. 
     As already mentioned, the dosage indicator sleeve can form the dosage scale or the pointer of the dosage indicator; in some preferred embodiments, it forms the dosage scale. The dosage scale can be formed on an upper surface area of the dosage indicator sleeve such that it runs back into itself. When selecting the dosage in such an embodiment, however, the dosage indicator sleeve may only be able to perform a single revolution, as a result of which the indicator fineness would suffer, or the dosage which could be selected would be very limited. A solution comprising multiple dosage indicator sleeves would be conceivable, but would increase the complexity of the mechanism. In order to avoid these disadvantages, in some embodiments, the dosage scale can encircle a longitudinal axis of the dosage indicator sleeve in a spiral. Essentially the same advantage would also be achieved if a dosage scale encircling in a spiral on the casing were provided and the dosage indicator sleeve formed the pointer for said dosage scale. Using a dosage scale encircling in a spiral, it is possible to select a large dosage with sufficient dosing fineness and good legibility of the dosage scale. If the dosage scale is spiral, the movement of the dosage indicator sleeve should correspondingly be a movement composed of rotation and translation. In one preferred embodiment, the dosage indicator sleeve is coupled to the casing via a threaded engagement, in order to obtain such a superimposed, well-defined movement. 
     In accordance with a preferred embodiment of the present invention, the dosing and activating button is either spring-elastic, or supported spring-elastically on the transfer means, in the activating direction. The same elasticity force against which the dosing and activating button spring-deflects in the activating direction pushes counter to the activating direction, against a stopper. The spring deflection is advantageous for the delivery movement, since the user of the administering apparatus cannot simply press against a fixed stopper when activating the dosing and activating means. Rather, in the front end position of the dosing and activating means, the dosing and activating button spring-elastically gives a little way further in the activating direction under the pressure from the user. In order to spring-deflect the dosing and activating button relative to the transfer means in this way, the blocking member preferably forms a stopper in the blocking engagement. If the blocking member is inserted into a cavity formed on the dosing and activating button in order to establish the blocking engagement, such a cavity can exhibit a greater extension in the activating direction than would be possible with a rigid stopper of the dosing and activating button, due to the spring-deflection movement. 
     As already mentioned, in some embodiments, the blocking member is moved into a cavity formed on the dosing and activating means, preferably on the dosing and activating button, in order to establish the blocking engagement. In one preferred embodiment, a groove which encircles on an upper surface area of the dosing and activating means forms the cavity. Equally, however, the cavity in its entirety can also be formed by a plurality of separate cavities which are formed on such an upper surface area spaced from each other, in some preferred embodiments, circumferentially. In principle, a single cavity at a single point on the dosing and activating means would alone be sufficient, but would be disadvantageous with respect to selecting the dosage. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  depicts a product delivery device in accordance with the present invention in an initial state, before a dosage is selected for the first time; 
         FIG. 2  depicts the product delivery device of  FIG. 1  in an end state, in which a piston rod of the device assumes a foremost position and is in engagement with a dosing member; 
         FIG. 3  depicts the product delivery device of  FIG. 1  in a state in which the piston rod and the dosing member are out of engagement and the piston rod has been reset to a rearmost initial position; 
         FIG. 4  is a cross-section along line A-A in  FIG. 2 ; 
         FIG. 5  is a cross-section along line B-B in  FIG. 3 ; 
         FIG. 6  depicts the piston rod, the dosing member and gear members of a cam gear in a three-dimensional section, wherein the piston rod and the dosing member are in engagement; 
         FIG. 7  depicts the piston rod, the dosing member and the gear members in a three-dimensional section, wherein the piston rod and the dosing member are out of engagement; 
         FIG. 8  depicts components of an embodiment of the device in accordance with the present invention in a three-dimensional representation; 
         FIG. 9  depicts a dosage indicator sleeve and components in accordance with the present invention co-operating with the dosage indicator sleeve in a three-dimensional representation; and 
         FIG. 10 , including  FIGS. 10   a - d , depicts an embodiments of the dosage indicator sleeve in accordance with the present invention, in multiple representations. 
     
    
    
     DETAILED DESCRIPTION 
     The figures, including  FIGS. 1-3 , show one embodiment of a device for delivering a selected dosage of a liquid product or substance. The product can in particular be a medicine or a therapeutic substance, for example insulin. 
     In one embodiment, the device comprises a casing in two parts, comprising a first, front casing portion  1  and a second, rear casing portion  2 , which are each formed as sleeve parts. The two casing portions  1 ,  2  are screwed together. The front casing portion  1  contains a reservoir R filled with the product. The reservoir R is formed by an exchangeable container, in the example embodiment by a hollow-cylindrical ampoule. The container is inserted from the rear into the front casing portion  1  until it abuts a stopper formed by the front casing portion  1 . At its front end, the container comprises an outlet A which is sterilely sealed by a septum. In order to be able to deliver the product from the reservoir R formed in this way, a cannula is introduced through the septum into the outlet A. At its rear end, the reservoir R is sealed tight by a piston K. Product is displaced from the reservoir R, i.e. delivered through the outlet A, by advancing the piston K in an advancing direction V, towards the outlet A, along a longitudinal axis L. 
     The piston K is moved in the advancing direction V by means of a piston rod  4  which is linearly guided along the longitudinal axis L, i.e. axially, by the casing. The piston rod  4  is operably coupled to a dosing and activating means which, in one embodiment, comprises a dosing sleeve  7 , a sleeve-shaped dosing and activating button  8  and a sleeve-shaped transfer element  10 . A split dosing member comprising, in one embodiment, two separate identical parts or members  11 ,  12 , is connected to said dosing and activating means. The dosing member is split axially into the two parts  11 ,  12 . The two parts are referred to in the following as the first dosing member  11  and the second dosing member  12 . The first dosing member  11  and the second dosing member  12  are each in a threaded engagement about the longitudinal axis L, which is simultaneously also the longitudinal axis of the piston rod  4 , with the piston rod  4  which is formed as a threaded rod. The first dosing member  11  and the second dosing member  12  are connected, secured against shifting axially and secured against rotating with respect to rotations about the longitudinal axis L, to the transfer element  10 . However, both the first dosing member  11  and the second dosing member  12  can be moved relative to the transfer element  10  and in particular relative to the piston rod  4  in a transverse direction with respect to the longitudinal axis L. In order for them to be able to move in the transverse direction, the transfer element  10  linearly guides the first dosing member  11  and the second dosing member  12  by forming a guiding shaft pointing generally transversely with respect to the longitudinal axis L for each of the two dosing members  11 ,  12 , the guiding shaft simultaneously also acting as a block against axial shifting and a block against rotating. As, for example, can be perceived on the basis of  FIGS. 6 and 7 , each of the guiding shafts comprises a side wall  10   a  pointing in the advancing direction V and a side wall  10   b  pointing counter to the advancing direction V. The side walls  10   a ,  10   b  each form a linear transverse guiding rail, pointing transversely with respect to the longitudinal axis, for one of the dosing members  11 ,  12 . Each one of the dosing members  11 ,  12  is enclosed and slide-guided between the two transverse guiding rails  10   a ,  10   b  of a guiding shaft, such that the two transverse guides formed by the pairs of transverse guiding rails  10   a ,  10   b  only permit sliding movements exactly perpendicular to the longitudinal axis L. The dosing members  11 ,  12  themselves form the guided engagement sliding pieces. The transverse guiding rails  10   a ,  10   b , in conjunction with the dosing members  11 ,  12 , form a part of a cam gear. 
     With respect to the form, function and co-operation of the components which co-operate for dosing and delivering the product, reference should additionally be made to  FIG. 8 . 
     In one embodiment, the dosing and activating button  8  is detachably connected to the transfer element  10 . The dosing and activating button  8  is composed of multiple individual parts, namely an outer sleeve part  8   a  protruding out of the rear casing portion  2 , an inserted inner sleeve part  8   b , an end button  8   c  which is inserted from the rear into the outer sleeve part  8   a  and locked, and a spring  8   d  which is axially tensed between the end button  8   c  and the inner sleeve part  8   b . The inner sleeve part  8   b  serves to fasten the dosing and activating button  8  to the transfer element  10  and may, therefore, be referred to in the following as the fastening part  8   b . The outer sleeve part  8   a  is accessible for the user for activating the administering apparatus and may, therefore, be referred to in the following as the activating part  8   a . The activating part  8   a  is connected, secured against shifting, to the end button  8   c  and supported on the fastening part  8   b  via the pressure-tensed spring  8   d . The activating part  8   a  can be moved in and counter to the advancing direction V relative to the fastening part  8   b  and therefore also relative to the transfer element  10 . The spring  8   d  presses the activating part  8   a  counter to the advancing direction V until it abuts the fastening part  8   b , such that it assumes the rear stopper position, shown in  FIGS. 1 to 3 , relative to the fastening part  8   b . Correspondingly, it can be moved relative to the fastening part  8   b  and the transfer element  10  in the advancing direction V by pressing against the elasticity force of the spring  8   d . This ability to move in the advancing direction V is advantageous for activating the dosing and activating means, which, due to this feature, can spring-deflect into itself. 
     In the following, the components  8   a  to  8   d  may be referred to in their entirety as the dosing and activating button  8 . 
     An encircling groove  9  is formed on the outer surface area of the dosing and activating button  8 , in the exemplary embodiment on the outer surface area of the outer sleeve part  8   a , in a portion surrounding the transfer element  10 . The groove  9  co-operates with a blocking member  45  which is formed annularly, surrounds the outer surface area of the dosing and activating button  8 , and is tensed radially inwardly against the outer surface area of the dosing and activating button  8  by means of a spring element  49 . 
     The dosing sleeve  7  is attached to the rear end of the rear casing portion  2  and can be rotated about the longitudinal axis L, relative to the rear casing portion  2 . At its rear end, the dosing sleeve  7  forms a collar which protrudes radially inwardly and forms teeth  7   a  ( FIG. 9 ) uniformly distributed over its inner circumference. On an outer surface area opposite the teeth  7   a , the dosing and activating button  8  forms linear, axial guiding grooves at a corresponding pitch, in each of which one of the teeth  7   a  is axially and linearly guided. In this way, the dosing sleeve  7  and the dosing and activating button  8  are secured against rotating about the longitudinal axis L, but are connected such that they can move axially relative to each other. 
     A piston rod holder  6  forms an axial linear guide for the piston rod  4 . The piston rod holder  6  is connected to the rear casing portion  2  such that it cannot move, in particular the piston rod holder  6  can neither be axially moved relative to the rear casing portion  2  or rotated about the longitudinal axis L. The piston rod holder  6  and the piston rod  4  can only move axially relative to each other. In this way, the piston rod  4  is axially and linearly guided relative to the rear casing portion  2 . 
     Between a rear end of the piston rod holder  6  and a collar, protruding radially inward, of a mechanism holder  5 , a sliding piece  15  is radially mounted over the first dosing member  11  and another sliding piece  16  is radially mounted over the second dosing member  12 , each secured against shifting axially, but radially and linearly guided and, in this sense, able to move radially. The sliding pieces  15 ,  16  have the same form and fulfil the same function, each with respect to the assigned first dosing member  11  and second dosing member  12 . The sliding pieces  15 ,  16  are arranged symmetrically with respect to the longitudinal axis L. The mechanism holder  5  is connected immovably to the rear casing portion  2 , so it cannot move axially relative to the rear casing portion  2 , to which end the three-quarter rib  56  serves as a stopper, and cannot rotate about the longitudinal axis L. 
     The sliding pieces  15 ,  16  form additional gear members of the cam gear. Since they are each in direct engagement with one of the dosing members  11 ,  12 , they may be referred to in the following as the gear output members of the cam gear. They each co-operate with a gear input member  20  formed as a sliding sleeve and referred to in the following using this designation. The sliding sleeve  20  forms another cam member and the two sliding pieces  15 ,  16  each form an engagement member of the cam gear. The sliding sleeve  20  can be axially moved relative to the first dosing member  11  and second dosing member  12 , the two sliding pieces  15 ,  16 , and relative to the rear casing portion  2 . Furthermore, it can be rotated about the longitudinal axis L relative to the rear casing portion  2 . A circular cylindrical inner surface area of the mechanism holder  5  forms a rotational sliding bearing and an axial linear guide for the sliding sleeve  20 . 
       FIGS. 4 and 5  show the cam gear with the split dosing member and the piston rod  4 , each in the same cross-section, relative to the dosing member, but in different gear states. The same gear states are shown in  FIGS. 6 and 7 , each in a three-dimensional section. Regarding the mode of operation of the cam gear, reference should additionally also be made to  FIGS. 4 to 7 . 
     The sliding pieces  15 ,  16  are each conical on their outer surface. The sliding sleeve  20  forms a corresponding counter cone on its inner surface facing the conical areas of the sliding pieces  15 ,  16 . The conical outer areas of the sliding pieces  15 ,  16  and the area of the counter cone of the sliding sleeve  20  are generally parallel to each other, forming a conical gap which is uniformly wide over the entire conical areas. 
     As can be perceived in  FIGS. 4 and 5 , the sliding sleeve  20  forms two guiding rails  21  for the sliding piece  15  and two guiding rails  22  for the sliding piece  16 . The sliding pieces  15 ,  16  form corresponding engagement rails  18  which are in sliding contact with the guiding rails  21 ,  22 . The guiding rails  21  are formed on the inner surface area of the sliding sleeve  20 , diametrically opposed to each other on both sides of the longitudinal axis L. The same applies to the guiding rails  22 . The guiding rails  21 ,  22  extend in the axial direction and each exhibit a substantially constant inclination with respect to the longitudinal axis L, i.e., the guiding rails  21 ,  22  are linear. The guiding rails  21  are generally parallel to each other, as are the guiding rails  22 . The guiding rails  21 ,  22 , formed on the left-hand side and right-hand side of the sliding sleeve  20  in the cross-section in  FIGS. 4 and 5 , run sagittally towards each other in the advancing direction V—as seen in the longitudinal section in FIG.  1 —at an acute angle bisected by a straight line parallel to the longitudinal axis L. When the sliding sleeve  20  moves axially relative to the sliding pieces  15  and  16 , the sliding pieces  15  and  16  are thus guided via their engagement rails  18  on the guiding rails  21 ,  22 , such that the sliding pieces  15 ,  16  are moved away from each other or towards each other transversely with respect to the longitudinal axis L, in this exemplary embodiment, exactly perpendicularly with respect to the longitudinal axis L. 
     The first dosing member  11  is accommodated, axially and linearly guided, in the sliding piece  15 . The second dosing member  12  is correspondingly accommodated, axially and linearly guided, in its sliding piece  16 . On their mutually facing lower sides, on the left-hand and right-hand side in the cross-section, the sliding pieces  15 ,  16  comprise stays  17  which protrude or extend inwardly towards each other. The sliding piece  15  grips behind the first dosing member  11  with its two stays  17 , and the sliding piece  16  grips behind the second dosing member  12  with its two stays  17 . If the two sliding pieces  15 ,  16  are moved away from each other, generally transversely with respect to the longitudinal axis L, then the stays  17  gripping behind the dosing members  11  and  12  move the two dosing members  11 ,  12  away from each other, generally transversely with respect to the longitudinal axis L, in the same way, and thus move them out of engagement with the piston rod  4 . When the sliding pieces  15 ,  16  move transversely towards each other, the sliding pieces  15 ,  16  again also press the dosing members  11 ,  12  towards each other via their surface areas, and thus back into engagement with the piston rod  4 . As already mentioned, the dosing members  11 ,  12  are axially guided in their respective sliding piece  15  and  16  such that they can shift linearly. The stays  17  form guiding rails for the linear guide, and the dosing members  11 ,  12  form engagement rails  13  guided on them, which the stays  17  grip behind. 
     The threaded engagement between the piston rod  4  and the split dosing member which exists in the state in  FIG. 1  is released by the casing portions  1 ,  2  moving axially relative to each other. This relative movement occurs when the casing portions  1 ,  2  are screwed apart. When the casing portions  1 ,  2  are screwed apart, the casing formed jointly by the casing portions  1 ,  2  is initially lengthened, which corresponds to the casing portions  1 ,  2  moving axially relative to each other. The relative movement between the casing portions  1 ,  2 , for example for exchanging the reservoir R, is thus used to release the engagement between the piston rod  4  and the split dosing member and the block against the piston rod  4  and the dosing and activating means axial shifting obtained by this engagement. 
     In order to be able to use the casing portions  1 ,  2  moving axially relative to each other to release the engagement, the sliding sleeve  20  is connected to the front casing portion  1  in such a way that it is slaved in its axial movement relative to the rear casing portion, while the sliding pieces  15 ,  16  retain their axial position relative to the rear casing portion  2 . Mounting the sliding pieces  15  and  16  between the mechanism holder  5  and the piston rod holder  6  ensures, as mentioned, that the sliding pieces  15 ,  16  are secured against shifting axially. The coupling of the sliding sleeve  20  on the front casing portion  1  forms a reservoir holding spring  37  which is axially pressure-tensed between the piston rod holder  6  and a reservoir holder  30  when the two casing portions  1 ,  2  are completely screwed together. To this end, the reservoir holding spring  37  is tensed between the piston rod holder  6  and the reservoir holder  30 . The reservoir holding spring  37  presses the reservoir holder  30  against the rear edge of the container which forms the reservoir R. The reservoir holding spring  37  presses the container against a stopper area formed in the front casing portion  1 . Arranging such a reservoir holding spring  37  is common in order to equalise length tolerances of the container, the casing portions  1 ,  2  and the components on which the container is supported in the longitudinal direction. 
     A slaving means  25  is fastened, secured against shifting and secured against rotating, to the reservoir holder  30 . The slaving means  25  forms a transfer member between the reservoir holder  30  and the sliding sleeve  20 , when the reservoir holder  30  follows an axial movement of the front casing portion  1  due to the spring force of the reservoir holding spring  37 . The sliding sleeve  20  and the slaving means  25  grip behind each other such that the sliding sleeve  20  is slaved by the slaving means  25  during the axial movement. In the exemplary embodiment, a tolerance equalisation spring  38  is axially tensed between the sliding sleeve  20  and the slaving means  25 . In principle, however, the sliding sleeve  20  and the slaving means  25  could also be rigidly connected to each other with respect to the axial direction. In any event, a rotational movement about the longitudinal axis L is possible between the sliding sleeve  20  and the slaving means  25 . In this respect, the rotational joint between the dosing and activating means and the rear casing portion  2  is formed between the sliding sleeve  20  and the slaving means  25 . 
     How the gear components  20 ,  25  and  30  are assembled and arranged relative to the piston rod holder  6  can be perceived in  FIG. 8 . The mutually facing collars  31 ,  61  of the reservoir holder  30  and piston rod holder  6  in particular can for instance be recognized, between which the reservoir holding spring  37  is tensed. The reservoir holder  30  comprises a circular cylindrical front sleeve part including a collar  31 . Multiple shoes  32  project backwards from the sleeve part. A locking cam  34  which protrudes radially outwards is formed at the rear end of each of the shoes  32 . Furthermore, each of the shoes  32  comprises lateral guides  33 . The reservoir holder  30  together with its shoes  32  can be inserted between a radially outer and middle sleeve part of the piston rod holder  6 . To this end, a sleeve base of the piston rod holder  6  comprises cavities corresponding to the shoes  32 . The piston rod holder  6  and the reservoir holder  30  are connected to each other, secured against rotating, via the shoes  32  and the cavities. From the rear side, the slaving means  25  is pushed onto the reservoir holder  30  via the middle sleeve part of the piston rod holder  6 . Tongues  27  project from a rear sleeve part of the slaving means  25 , corresponding in number and arrangement to the shoes  32 . Each one of the tongues  27  is pushed onto one of the shoes  32  and locked by means of the locking cams  34 , wherein the locking cams  34  lock into cavities  28  formed correspondingly on the tongues  27 . The connection between the slaving means  25  and the reservoir holder  30  can be regarded as substantially completely rigid. 
     The sliding sleeve  20  comprises a rear sleeve part and a plurality of elastically bending tongues  23 , which project from the sleeve part and protrude toward the slaving means  25  in the advancing direction V. Slaving cams  24  are formed at the front ends of the tongues  23  and project radially outward from the tongues  23 . When the slaving means  25  moves axially, the sliding sleeve  20  is slaved or driven by an engagement which exists when the slaving cams  24  are connected to a slaving collar  26  which protrudes radially inward at the rear end of the slaving means  25  and which the slaving cams  24  grip behind when connected. The engagement simultaneously enables relative rotational movements about the longitudinal axis L. 
     Furthermore, it can also be recognized in  FIG. 8  how the mechanism holder  5  and the piston rod holder  6  are connected, secured against shifting and secured against rotating. Elastically bending tongues  63 , comprising locking cams  64  protruding radially outward, project backwards from the sleeve part of the piston rod holder  6 . Via the locking cams  64 , the piston rod holder  6  locks in corresponding cavities  52  of the mechanism holder  5 . Furthermore, a block against rotating between the mechanism holder  5  and the piston rod holder  6  is obtained by engaging a guiding protrusion  62 , which axially projects from the piston rod holder  6 , with a guiding cavity  51  of the mechanism holder  5 . The mechanism holder  5  and the piston rod holder  6  are connected to each other, secured against shifting and secured against rotating, via the locking connection of the locking cam  64  and the guide of the guiding protrusion  62 . The mechanism holder  5  is connected to the rear casing portion  2 , secured against shifting and secured against rotating, such that the same also applies to the piston rod holder  6 . 
     A restoring spring  36  is axially tensed between the piston rod holder  6  and the transfer element  10  of the dosing and activating means. The restoring spring  36  serves to restore or reset the dosing and activating means, the split dosing member and the piston rod  4  after the product has been delivered. 
     In one embodiment, the device in accordance with the present invention further comprises a dosage indicator sleeve  40 , which is provided on its outer surface area with a dosage scale  41 . The dosage indicator sleeve  40  is shown in a three-dimensional view from the side in each of  FIGS. 8 and 9 , and in two longitudinal sections, a front view and a rear view in  FIG. 10 . It is in threaded engagement with the mechanism holder  5 . The threaded engagement exists between an outer thread  53  in a rear portion of the mechanism holder  5  and an inner thread  42  of the dosage indicator sleeve  40 . The threaded axis of the two threads  42  and  53  coincides with the longitudinal axis L. The dosage scale  41  is formed by dosage values arranged, encircling in a spiral, on the outer surface area of the dosage indicator sleeve  40 . In the exemplary embodiment, numbers corresponding to the dosage units which can be selected form the dosage values. The dosage indicator sleeve  40  is connected to the dosing sleeve  7  such that it can be axially and linearly shifted, but is secured against rotating with respect to the longitudinal axis L. For this purpose, the rear end of the dosage indicator sleeve  40  comprises a plurality of radially projecting guiding cams  43  which protrude into and are axially and linearly guided in corresponding guiding grooves  7   b  ( FIG. 9 ) on the inner surface area of the dosing sleeve  7 . Due to this engagement, the dosage indicator sleeve  40  is also rotated about the longitudinal axis L when the dosing sleeve  7  is rotated. Due to the threaded engagement with the mechanism holder  5 , the dosage indicator sleeve  40  is thus screwed backwards, counter to the advancing direction V, relative to the mechanism holder  5  and, therefore, also relative to the rear casing portion  2 , when the dosage is selected by rotating the dosing sleeve  7 . 
     The portion of the dosage indicator sleeve  40  which forms the inner thread  42  and the dosage scale  41  protrudes or extends into an annular gap which remains between the rear casing portion  2  and the mechanism holder  5 . In the radially outer portion opposing the dosage scale  41 , the rear casing portion  2  comprises a window  3  through which the dosage scale  41  can be read. The pitch of the inner thread  42  corresponds to the pitch of the spiral dosage scale  41 . 
     The blocking member  45  already mentioned, which due to its form may be referred to in the following as the blocking ring, is arranged radially inwards from a longitudinal portion of the dosage indicator sleeve  40 , which protrudes backwards beyond the mechanism holder  5 . The blocking ring  45  is mounted, secured against rotating and secured against shifting axially, in a sleeve part of a blocking ring holder  47 . The blocking ring holder  47  is fastened, secured against rotating and shifting, to the mechanism holder  5 , via a guiding area  54  of the mechanism holder  5  and a locking connection formed between a locking cam  55  of the mechanism holder  5  and a cavity  48  of the blocking ring holder  47  ( FIG. 8 ). 
     The blocking ring  45  forms a counter reset cam  46  which protrudes radially outwards from the outer surface area of the blocking ring  45  towards the dosage indicator sleeve  40 . A reset cam  44  projects radially inwards from the facing inner surface area of the dosage indicator sleeve  40  ( FIG. 10 ). The reset cam  44  is formed in a rotational angular position with respect to the dosage scale  41 , such that it is in radial alignment with the counter reset cam  46  and presses radially against the cam  46  precisely when the dosage indicator sleeve  40  assumes a zero-dosage position relative to the rear casing portion  2 , in which the dosage value corresponding to the zero-dosage is indicated in the window  3 . If the dosage indicator sleeve  40  assumes a position with respect to the mechanism holder  5  and the rear casing portion  2  which does not correspond to the zero-dosage, then the counter reset cam  46  is free from the reset cam  44 , i.e., a radially slight distance remains between the counter reset cam  46  and the facing inner surface area of the dosage indicator sleeve  40 . 
     The blocking ring  45  can be moved linearly relative to the blocking ring holder  47 , radially with respect to the longitudinal axis L. Diametrically opposite the counter reset cam  46  with respect to the longitudinal axis L, the spring element  49  is arranged between the blocking ring  45  and the blocking ring holder  47  and presses the blocking ring  45  against the outer surface area of the dosing and activating button  8 . The spring element  49  acts as a pressure spring. 
     The functionality and method of operation of the device in accordance with the present invention is described below with reference to  FIGS. 1 to 3 , in each of which the device is shown in a different state. Reference should also additionally be made to the other figures. 
     In  FIG. 1 , the device assumes an initial state in which the reservoir R is completely filled with the product and from which the dosage can be selected. The dosage indicator sleeve  40  assumes its position corresponding to the zero-dosage, i.e., the dosage value corresponding to the zero-dosage can be read through the window  3 . The dosing and activating means (comprising, in one embodiment, the dosing sleeve  7 , dosing and activating button  8  and transfer element  10 ), together with the piston rod  4 , assumes its rearmost position, in which the dosage is selected. In this dosage selection position, a slight axial distance H 1  remains between the piston rod  4  and the piston K. An equally large, slight axial distance H 2  remains between two stopper areas which face each other axially, one of which is formed by the piston rod holder  6  and the other of which is formed by the transfer element  10  and which define a front end position for the transfer element  10  and the piston rod  4 . The slight axial distance H 2  between this pair of stopper areas is the maximum stroke of the piston rod  4 . Selecting the dosage reduces the slight axial distance H 1  between the piston K and the piston rod  4 . If, within the context of the delivery movement, the piston rod  4  is then moved in the advancing direction V by the always equally long stroke H 2  as far as its front end position, then the reduction in the slight distance H 1  between the piston rod  4  and the piston K while selecting the dosage corresponds to the product dosage delivered. 
     The split dosing member (comprising, in one embodiment, dosing members  11 ,  12 ) is coupled to the dosage indicator sleeve  40  via the dosing and activating means, such that the axial distance H 1  between the piston K and the piston rod  4  is at a maximum, i.e., H 1 =H 2 , when the dosage indicator sleeve  40  assumes its zero-dosage position. 
     To select the dosage, the dosing sleeve  7  is rotated about the longitudinal axis L relative to the rear casing portion  2 , wherein the dosing and activating button  8  is also rotated due to its engagement, secured against rotating, with the dosing sleeve  7 . Due to these connections, secured against rotating, the transfer element  10  and therefore also the split dosing member are also necessarily rotated together. Since the piston rod  4  is axially and linearly guided by the piston rod holder  6 , the rotational movement of the split dosing member causes a dosing movement of the piston rod  4  directed in the advancing direction, via the threaded engagement. This shortens the slight distance H 1  between the piston rod  4  and the piston K by a length corresponding to the selected product dosage; it does not alter the slight distance H 2 . 
     Due to its engagement, secured against rotating, the dosage indicator sleeve  40  is slaved or driven correspondingly by the dosing sleeve  7  during the rotational dosing movement and rotated about the longitudinal axis L relative to the mechanism holder  5 . Due to the threaded engagement between the mechanism holder  5  and the dosage indicator sleeve  40 , an axial movement counter to the advancing direction V is superimposed on the rotational movement of the dosage indicator sleeve  40 . As an aside, it may be mentioned that the pitch of the engaged threads  42  and  53  of the dosage indicator sleeve  40  and mechanism holder  5  is greater than the pitch of the engaged threads of the piston rod  4  and split dosing member. Correspondingly, the axial path which the dosage indicator sleeve  40  travels per revolution is larger than the axial path by which the piston rod  4  is moved per revolution of the split dosing member. This benefits the legibility of the dosage scale  41 . As soon as the dosage indicator sleeve  40  has been moved, relative to the mechanism holder  5 , out of its zero-dosage position by at least one dosage unit, the blocking ring  45  is free from the reset cam  44 . The dosage value which can be read on the dosage scale  41  through the window  3  corresponds to the axial length by which the distance H 1  is shortened by the dosing movement. 
     In order to deliver the selected product dosage through the outlet A of the reservoir R, the dosing and activating button  8  is pressed in the advancing direction V, into the rear casing portion  2 , i.e., it is activated. The advancing direction V is therefore also simultaneously the activating direction of the dosing and activating button  8 . Activating the dosing and activating button  8  also moves the components which are connected, secured against shifting axially, to the dosing and activating button  8 , namely the transfer element  10 , the split dosing member and, due to the threaded engagement also the piston rod  4 , in the advancing direction V by the stroke length H 2 . During this stroke movement, the piston K is advanced in the advancing direction V by a path length which corresponds to the length by which the slight distance H 1  between the piston rod  4  and the piston K is shortened as compared to the stroke H 2  by selecting the dosage. 
       FIG. 2  shows the exemplary device in an end state in which, after repeated administering, the maximum product amount which can be delivered from the reservoir R with the aid of the device has been delivered, i.e., the reservoir R has been emptied. The dosing and activating button  8  has been pressed into the rear casing portion  2  by the stroke length H 2 . In this axial position of the dosing and activating button  8 , its groove  9  is in radial alignment below the blocking ring  45 . The groove  9  is slightly wider in the radial direction than the blocking ring  45 , in order to still be able to accommodate the blocking ring  45  when the dosing and activating button  8  is spring-deflected. For the pressure from the user, required for activating the dosing and activating button  8 , spring-deflects the dosing and activating button  8  a little way into itself, in the front end position of the transfer element  10  and the piston rod  4 , which is regarded as touch-sense pleasant. Since the blocking ring  45  is tensed against the outer surface area of the dosing and activating button  8  by the spring element  49 , the blocking ring  45  is inserted radially into the groove  9  which is then accessible for it. The larger width of the groove  9  as compared to the blocking ring  45 , in combination with the axial spring-deflection of the dosing and activating button  8 , increases the reliability that the blocking ring  45  will indeed be inserted into the groove  9  and the dosing and activating means blocked. The blocking ring  45  forms an axial stopper for the spring-deflection movement of the dosing and activating button  8 . Diametrically opposite the spring element  49 , inserting the blocking ring  45  moves its counter reset cam  46  radially towards the inner surface area of the dosage indicator sleeve  40 . Since the blocking ring  45  is connected to the mechanism holder  5  such that it cannot move axially in the blocking ring holder  47 , the dosing and activating button  8  and therefore the piston rod  4  together cannot be moved back again counter to the advancing direction V, i.e., the blocking ring  45  and the dosing and activating button  8  are in a blocking engagement. Thus, in the foremost position of the dosing and activating means, the blocking-engaged blocking ring  45  seated in the groove  9  forms an axial block for the dosing and activating means, the split dosing member and the piston rod  4 . In this end state, the restoring spring  36  is axially pressure-tensed. The restoring spring  36  is prevented from being relieved by the axial block formed by the blocking ring  45 . This axial block ensures that the product can only be selected anew from a defined position of the dosage indicator sleeve  40 . This defined position is preferably—as in the exemplary embodiment—the zero-dosage position, i.e., the position in which the zero-dosage can be read on the dosage scale  41  through the window  3 . 
     In order to exchange the emptied reservoir R for a new reservoir R, the two casing portions  1 ,  2  are screwed apart. Due to the screwing procedure, the casing portions  1 ,  2  are moved axially relative to each other. During the movement of casing portions  1 ,  2  which lengthens the casing, the tensed reservoir holding spring  37  presses the reservoir holder  30  relative to the piston rod holder  6  in the advancing direction V until it abuts a stopper formed by the rear casing portion  2 . Before the screwing movement is begun, a sufficiently large, slight distance remains axially between a front end of the reservoir holder  30  and the stopper formed by the rear casing portion  2 , to enable the reservoir holder  30  to move axially relative to the piston rod holder  6 . 
     As the reservoir holder  30  moves axially relative to the piston rod holder  6 , it slaves the slaving means  25  and the sliding sleeve  20 . Due to the axial movement of the sliding sleeve  20 , the two sliding pieces  15 ,  16  move radially outwards on the oblique guiding rails  21 ,  22  of the sliding sleeve  20 . As they move radially outwards in this way, the sliding pieces  15 ,  16  are linearly guided by the mechanism holder  5  and the piston rod holder  6 . Since the stays  17  of the sliding piece  15  grip behind the first dosing member  11  and the stays  17  of the sliding piece  16  grip behind the second dosing member  12 , the first dosing member  11  and the second dosing member  12  are moved radially apart in the same way, and are thus moved out of their threaded engagement with the piston rod  4 . The axial movement which the rear casing portion  2  performs relative to the front casing portion  1  in order to release the engagement between the piston rod  4  and the dosing members  11 ,  12  may be referred to as a disengaging movement. The disengaging movement moves each of the dosing members  11 ,  12  to a position retracted from the piston rod  4 . In the opposite, engaging movement, in which the rear casing portion  2  performs an axial movement in the reverse direction relative to the front casing portion  1 , the dosing members  11 ,  12  are moved back into engagement with the piston rod  4  by the cam gear formed by sliding sleeve  20  and the sliding pieces  15 ,  16 . Starting with the casing portions  1 ,  2  completely screwed together, the disengaging movement and the engaging movement occur in a first portion of the screwing movement. This first portion of the screwing movement is complete when the reservoir holding spring  37  has pressed the reservoir holder  30  against the stopper formed by the rear casing portion  2 . 
       FIG. 3  shows the device in a state in which the threaded engagement between the split dosing member and the piston rod  4  has been released and the piston rod  4  can thus be freely shifted axially in the piston rod holder  6 . The rear casing portion  2  has just completed its disengaging movement. In the state shown, the piston rod  4  has already been reset to its rearmost position. The piston rod  4  can thus slide back, guided by the piston rod holder  6 , to the end position shown, for example by gently tilting the entire device. At the rear end of the dosing button  8 , a rubber stopper projects inwards in the advancing direction V and gently damps or stops the sliding movement of the piston rod  4 . 
     As the casing portions  1 ,  2  are screwed further apart, the positions assumed by the dosing members  11 ,  12 , the sliding pieces  15 ,  16 , the sliding sleeve  20  and the reservoir holder  30  relative to the rear casing portion  2  are no longer altered. This is ensured by the reservoir holder  30  abutting the rear casing portion  2 . The two casing portions  1 ,  2  can be screwed completely apart and the spent reservoir R exchanged for a new one. After a new reservoir R has been inserted into the front casing portion  1 , the two casing portions  1 ,  2  are screwed back together. In the final portion of the screwing movement, the rear casing portion  2  performs its engaging movement relative to the front casing portion  1 , in which the reservoir holder  30  comes into contact with the reservoir R or a reservoir holder and is pressed by the latter axially towards the piston rod holder  6 , against the spring force of the reservoir holding spring  37 . As it axially moves, the reservoir holder  30  also presses the sliding sleeve  20 , via the slaving means  25 , backwards counter to the advancing direction V. This moves the sliding pieces  15 ,  16  radially inwards via their guiding engagement with the sliding sleeve  20 , until the synchronous engagement between the dosing members  11 ,  12  and the piston rod  4  is re-established. 
     Where, in the above, resetting the piston rod  4  is only described for a completely spent reservoir R, it should be noted that the piston rod  4  can also be reset in accordance with the invention from any other axial position of the piston rod  4  in which the piston rod  4  has been moved out of its rearmost position shown in  FIG. 1  by a rotational dosing movement by the split dosing member. 
     When the dosing and activating button  8  is pressed into in the rear casing portion  2  to its foremost position, as in  FIGS. 2 and 3 , there is no longer a block against rotating between the dosing sleeve  7  and the dosing and activating button  8 , i.e., the dosing sleeve  7  can be freely rotated about the longitudinal axis L relative to the dosing and activating button  8  and rear casing portion  2 . However, the block against rotating between the dosing sleeve  7  and the dosage indicator sleeve  40  still exists. In order to return the dosing and activating button  8  and, therefore, the dosing and activating means and split dosing member together to the dosage selection position, the dosing sleeve  7  is rotated about the longitudinal axis L in a rotational direction which guides the dosage indicator sleeve  40  back to the zero-dosage position. During this rotational movement, the dosage indicator sleeve  40  is rotated relative to the mechanism holder  5 . As a result of the threaded engagement with the mechanism holder  5 , the dosage indicator sleeve  40  completes a translational and rotational movement relative to the mechanism holder  5  and rear casing portion  2 , towards its zero-dosage position. In a final movement portion before reaching the zero-dosage position, the length of which corresponds to a single settable dosage unit, the reset cam  44  of the dosage indicator sleeve  40  radially overlaps with the counter reset cam  46  of the blocking ring  45 . The reset cam  44  is tapered in the circumferential direction on the side which presses against the counter reset cam  46  while the dosage indicator sleeve  40  is rotated back. Tapering enables the two cams  44  and  46  to gradually and gently slide over each other. The reset cam  44 , which gradually lengthens radially inwards in its tapered region, moves the blocking ring  45  radially out of the groove  9 , against the restoring force of the spring element  49 . The axial block is thus released, and the restoring spring  36  presses the dosing and activating means, together with the piston rod  4 , back to the initial position shown in  FIG. 1 . 
     The sequence of selecting the dosage, delivering the selected dosage by activating the dosing and activating means, axially blocking with the blocking ring  45  via the cam  46 , rotating the dosage indicator sleeve  40  back to the zero-dosage position and thus releasing the axial block and springing the dosing and activating means  7 / 8 / 10  back to the initial position, can be repeated until the reservoir R has been emptied. The cam  46  and reset cam  44  co-operating couples the movement of the dosing and activating means back to the initial position, from which a dosage can be selected anew, to the zero-dosage position of the dosage indicator sleeve  40 . This coupling is advantageously configured such that the movement of the dosing and activating means is only possible when the dosage indicator sleeve  40  assumes its zero-dosage position, and no other hand operations are required in order to trigger the resetting movement of the dosing and activating means. 
     In one embodiment of the present invention, the product delivery device of the exemplary embodiment may be used with or provided for an inhaler such as those known to those skilled in art, using which insulin is administered via the airways. The device of the invention serves to dose and deliver the product into an atomising chamber. The product thus provided in doses in the atomising chamber is atomised by an atomising means and administered through a chamber outlet via the airways, preferably orally. The front end of the front casing portion  1  is provided with a connector G formed as a thread, in order to be able to connect the device to the atomising chamber by threaded engagement. 
     In some embodiments of the present invention, the device can also easily be used directly as an injection apparatus, by screwing a needle holder comprising an integrated injection needle of preferably 30 G or thinner, for example 31G, onto the front end of the front casing portion  1 . 
     In some embodiments, the device in accordance with the present invention could also be used with or provided for a pressure injector and, in this instance, be connected to a discharge means of the pressure injector. The device would supply the selected product dosage to the discharge means and the discharge means would discharge said product dosage at high pressure through an injection nozzle. 
     In the foregoing description, embodiments of the present invention, including preferred embodiments, have been presented for the purpose of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms and steps disclosed. Obvious modifications or variations are possible in light of the above teachings. The embodiments were chosen and described to provide the best illustration of the principals of the invention and its practical application, and to enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the invention as determined by the appended claims when interpreted in accordance with the breadth they are fairly, legally, and equitably entitled.