DRUG INJECTION DEVICE WITH CARTRIDGE HOLDER AUTOMATICALLY OPERATING CLUTCH ALLOWING RESET OF DRIVE MECHANISM AND DRIVE SPRING RE-LOADING UPON CARTRIDGE EXCHANGE

Abstract

The present disclosure relates to an injection device for setting and dispensing of a dose of a medicament, the device comprising: an elongated main housing to accommodate a cartridge filled with the medicament and defining an axial direction, a piston rod arranged inside the main housing and extending in axial direction along a first axis to operably engage with a piston of the cartridge, a reset member axially displaceable inside the main housing between a proximal operating position and a distal reset position along a second axis radially offset from the first axis to switch the device between a reset mode and an operating mode, a cartridge holder releasably attachable to a distal end of the main housing on the first axis to accommodate a distal end of the cartridge, wherein the cartridge holder comprises a sidewall portion with a radially outwardly protruding lock member to axially engage with the reset member located radially adjacent the cartridge holder.

Claims

1. An injection device for setting and dispensing of a dose of a medicament, the device comprising: an elongated main housing (11) to accommodate a cartridge (6) filled with the medicament and defining an axial direction (3, 4), a piston rod (130) arranged inside the main housing (11) and extending in axial direction along a first axis (3) to operably engage with a piston of the cartridge (6), a reset member (40) axially displaceable inside the main housing (11) between a proximal operating position (0) and a distal reset position (R) along a second axis (4) radially offset from the first axis (4) to switch the device between a reset mode and an operating mode, a cartridge holder (140) releasably attachable to a distal end of the main housing (11) on the first axis (3) to accommodate a distal end of the cartridge (6), wherein the cartridge holder (140) comprises a sidewall portion (147) with a radially outwardly protruding lock member (144) to axially engage with the reset member (40) located radially adjacent the cartridge holder (130).

2. The injection device according to claim 1, wherein the reset member (40) is displaceable in distal direction and into the reset position (R) under the action of at least one spring element (70, 76).

3. The injection device according to claim 1 or 2, wherein a distal end (41) of the reset member (40) axially abuts with the inside of a distally located front face (14) of the main housing (11) when reaching the distal reset position (R).

4. The injection device according to any one of the preceding claims, wherein a cam portion (145) of lock member (144) tangentially engages a distal edge (42) of the reset member (40) such that the reset member (40) is displaced in proximal direction (2) towards the operating position (O) when the cartridge holder (140) is twisted relative to the main housing (11) with regard to the first axis (3).

5. The injection device according to claim 3 or 4, wherein the lock member (144) is axially sandwiched between the reset member (40) and the inside of the main housing's (11) front face (14) when the reset member (40) is in the operating position (O).

6. The injection device according to any one of the preceding claims, wherein the reset member (40) is axially engaged with a dose indicator (80) rotationally supported on the second axis (4) and having consecutive numbers or symbols showing up in a window (16) of the main housing (11) when subject to a dose incrementing rotation during dose setting or when subject to a dose decrementing rotation during dose dispensing.

7. The injection device according to claim 6, wherein the dose indicator (80) comprises a detent structure (82) at a distal end (81) to engage with a corresponding detent structure (17) of the main housing (11) when reaching the reset position (R).

8. The injection device according to any one of the preceding claims, further comprising a dispensing member (30) aligned along the second axis (4) with a distal shaft portion (31) and a proximal button portion (32), wherein the dispensing member (30) is displaceable in distal direction (1) against the action of a dispensing spring element (70) to switch from a dose setting mode (S) into a dose dispensing mode (D).

9. The injection device according to any one of the preceding claims, further comprising a drive sleeve (100) permanently rotationally coupled to the piston rod (130), rotationally biased by a mainspring (126), rotationally locked to the main housing (11) in dose setting mode (S) and rotationally released from the main housing (11) in dose dispensing mode (D).

10. The injection device according to any one of the preceding claim 8 or 9, further comprising a ratchet member (60) permanently axially and rotationally locked to the dispensing member (30).

11. The injection device according to claims 10, wherein the ratchet member (60) is alternately in a ratchet engagement: with the drive sleeve (100) when in dose setting mode, or with the reset member (40) when in a reset mode.

12. The injection device according to any one of the preceding claim 10 or 11, wherein the ratchet member (60) is rotationally locked to the dose indicator (80) when in dose setting mode (S) and wherein the ratchet member (60) is rotationally released from the dose indicator (80) when in dose dispensing mode (D).

13. The injection device according to any one of the preceding claims 10 to 12, wherein the reset member (40) axially engages with the ratchet member (60) when approaching the distal reset position (R), thereby distally displacing the ratchet member (60) into a reset position in which it is disengaged from the drive sleeve (100).

14. The injection device according to any one of the preceding claims 9 to 13, wherein the dispensing member (30) is in axial abutment with the drive sleeve (100) to displace the drive sleeve (100) into a distal reset position, in which the drive sleeve (100) is rotatably released from the main housing (11) and from the dose indicator (80).

15. The injection device according to any one of the preceding claims 9 to 14, wherein the dispensing member (30) axially intersects the hollow drive sleeve (100) and wherein a proximal head (44) of the reset member (40) located inside the dispensing member (40) engages with at least one latch member (33) of the dispensing element (30) during distally directed displacement towards the reset position (R) thereby activating a torque-proof clutch (C4) between drive sleeve (100) and the dispensing member (30).

Description

BRIEF DESCRIPTION OF THE FIGURES

[0127] In the following, a non-limiting embodiment of the injection device with its drive mechanism is described in detail by making reference to the drawings, in which:

[0128] FIG. 1 shows a perspective view of the injection device,

[0129] FIG. 2 shows an exploded and perspective view of the various device components,

[0130] FIG. 3 is a cross-section through the injection device when in dose setting mode,

[0131] FIG. 4 is an enlarged view of a portion of the cross-section according to FIG. 3,

[0132] FIG. 5 shows a cross-section through the injection device in dose dispensing mode,

[0133] FIG. 6 is an isolated view of a main housing portion of the injection device,

[0134] FIG. 7 is a perspective illustration of the dose indicator,

[0135] FIG. 8 shows a dose indicating mechanism in a zero dose configuration,

[0136] FIG. 9 shows the dose indicating mechanism after a dose of a particular size has been set,

[0137] FIG. 10 shows another side view of the device according to FIG. 9,

[0138] FIG. 11 is a perspective and partially cut view through the proximal end of the device,

[0139] FIG. 12 is another perspective and partially cut view through a middle section of the

[0140] FIG. 13 shows a ratchet engagement between a portion of the main housing and a drive member during dose dispensing,

[0141] FIG. 14 shows the arrangement of a bias spring at a proximal end of the cartridge,

[0142] FIG. 15 shows an isolated and perspective view of the bias spring,

[0143] FIG. 16 shows the injection device just after removal of a cartridge holder,

[0144] FIG. 17a is an enlarged view of a distal portion of the cross-section according to FIG. 16,

[0145] FIG. 17b is an enlarged view of a middle section of the device according to FIG. 16,

[0146] FIG. 18 shows the device after reaching the reset position,

[0147] FIG. 19a is an enlarged view of a distal end of the device according to FIG. 18,

[0148] FIG. 19b is an enlarged view of the proximal end of the device according to FIG. 18,

[0149] FIG. 20 is illustrative of the device according to FIG. 18 during a reset operation,

[0150] FIG. 21 is illustrative of the device after replacement of the cartridge, and

[0151] FIG. 22 shows the device according to FIG. 21 with the cartridge holder connected thereto,

[0152] FIG. 23a shows the cartridge holder in an unlocked configuration,

[0153] FIG. 23b shows the cartridge holder when twisted towards a locking configuration thereby engaging a distal edge of the reset member with its cam portion and

[0154] FIG. 23c shows the cartridge holder when in locked configuration, thereby axially proximally displacing the reset member into the operating position.

DETAILED DESCRIPTION

[0155] The injection device 5 as illustrated in FIG. 1 is configured as an all mechanically implemented auto-injector. It comprises a housing 10 featuring a main housing 11 of elongated shape and extending in an axial direction. The main housing 11 comprises a distal end facing in a distal direction 1 and further comprising a proximal end facing in a proximal direction 2. The housing 10 comprises a proximal housing portion 12 that is connectable with a proximal end of the main housing 11. The proximal housing portion 12 serves as a kind of a lid closing the tubular-shaped main housing 11 in proximal direction 2. As shown in FIG. 2, the proximal housing portion 12 comprises a proximally extending socket portion 12a that serves as a support and a bearing for a dose dial 20 being rotatably supported on the housing 10. The dose dial is rotationally supported on the housing portion 12 but is axially fixed thereto by means of at least one clip member 21 as shown in FIG. 19b.

[0156] In distal direction 1 the main housing 11 terminates with a distal front face 14 from which a detachable cartridge holder 140 axially protrudes. The cartridge holder 140 comprises a threaded socket 141 to threadedly engage with a piercing assembly, typically comprising a needle hub with a double-tipped injection needle. The cartridge holder comprises a through opening 142 in its distal front face to receive the proximal end of the injection needle. The cartridge holder 140 further comprises an outer gripping surface 143 that allows and supports to releasably attach the cartridge holder 140 to the main housing 11 through a twisting motion with regard to a first axis 3 extending parallel to the longitudinal extension of the main housing 11.

[0157] As it becomes further apparent from FIGS. 2-5 there is provided a second axis 4 along which a series of further components of the drive mechanism 8 of the injection device 5 are arranged. Almost all mechanical components of the injection device 5 as they are illustrated in FIG. 2 are located concentrically about one of the two principal axes 3, 4.

[0158] Along the first axis 3 there are located the cartridge 6 and the piston rod 130. The piston rod 130 is rotatably engaged with a sleeve-shaped drive member 110 so that a rotation of the drive member 110 axially fixed to the main housing 11 leads to a distally directed displacement of the piston rod 130. This distally advancing displacement may be obtained through a splined interconnection of piston rod 130 and drive member 110 and further by a threaded engagement of the piston rod 130 with a threaded flange portion 9 of the main housing 11. The piston rod 130 extends into the interior of the hollow drive member 110.

[0159] In an alternative embodiment it is also conceivable, that the piston rod 130 is in splined engagement with the main housing 11, i.e. the piston rod 130 is free to be axially displaced relative to the main housing 11 but is for instance threadedly engaged with the hollow drive member 110.

[0160] The drive member 110 is in permanent rotational engagement with a drive sleeve 100 which is arranged radially adjacent to the drive member 110. As can be seen from FIGS. 2 and 3, the drive member 100 is arranged along the second principal axis 4. Concentrically arranged with this second axis 4 there is further provided the sleeve-shaped dispensing member 30, the dose dial 20, a gauge element 90, the dose indicator 80, the ratchet member 60 as well as the reset member 40.

[0161] The dose dial 20 is axially fixed to the housing 10, in particular to the proximal housing portion 12, e.g. by way of mutually engaging latch or clip members 21, e.g. positively locked and positively engaged with a corresponding recess of the proximal housing portion 12. In this way, the dose dial 20 is rotatable relative to the housing 10. The dose dial is permanently rotatably locked to the dispensing member 30 having a proximal button portion 32 at least slightly proximally protruding from the proximal end of the dose dial 20 when in dose setting mode (S).

[0162] The dispensing member 30 further has a shaft portion 31 extending along the second axis 4. The dispensing member 30 comprises at least one, typically several radially outwardly biased snap members 34 at its distal end to permanently axially engage with a ratchet member 60. In this way, the dispensing member 30 and the ratchet member 60 are permanently axially and rotatably locked to each other. Axial displacement as well as a rotation of the dispensing member 30 equally transfers to the ratchet member 60; and vice versa.

[0163] There is further provided a drive sleeve 100 having a detent structure 102 at a proximally facing socket portion engaging with a correspondingly-shaped detent structure 18 of the housing 10. The detent structures 18, 102 form a first clutch C1 by way of which the drive sleeve 100 is rotationally locked to the housing 10 when in proximal dose setting position (S). The drive sleeve 100 further comprises a geared section 103 near or at its proximal end as shown in FIGS. 2 and 11. The geared section 103 is in permanent engagement with a correspondingly-shaped geared section 113 of the drive member 110. The geared engagement of drive sleeve 100 and drive member 110 is even invariant to slight axial displacement of the drive sleeve 100 relative to the drive member 110.

[0164] The drive sleeve 100 is axially intersected by the shaft portion 31 of the dispensing member 30. The drive sleeve 100 further comprises a threaded section 104 near its distal end which is threadedly engaged with a correspondingly threaded last dose limiting member 50 as shown in FIG. 12. The last dose limiting member 50 is furthermore in splined engagement with the inside facing portion of the dose indicator 80 through which the drive sleeve 100 axially extends. During dose setting the dose indicator 80 rotates relative to the rotationally locked drive sleeve 100, thereby inducing a corresponding rotation of the last dose limiter 50, which upon the threaded engagement with the drive sleeve 100 travels in axial direction, e.g. in proximal direction as a dose of increasing size is set.

[0165] There are provided mutually corresponding stop features on the outer circumference of the drive sleeve 100 and the last dose limiter 50. When reaching an end of content configuration, in which the dose to be set would exceed the amount of medicament left in the cartridge, the last dose limiter 50 is blocked from rotating further relative to the drive sleeve 100 thereby inhibiting any further dose incrementing rotation of the dose dial 20.

[0166] The ratchet member 60 as it is shown in FIGS. 2 and 12 comprises a proximal rim 61 and a distal rim 62 that are interconnected by at least one bridging portion 63. The proximal rim 61 comprises a toothed profile 64 on its radially outwardly facing circumference to selectively engage with a correspondingly toothed profile 84 of the dose indicator 80. In this way, ratchet member 60 and dose indicator 80 form a torque-proof clutch C3 as indicated in FIG. 3 that is releasable through a distally directed displacement of the ratchet member 60 relative to the main housing 11 and hence relative to the dose indicator 80.

[0167] The proximally facing surface of the proximal rim 61 features a ratchet profile 65 that is in engagement with a correspondingly-shaped ratchet profile 105 located at a distal end face of the drive sleeve 100.

[0168] In addition, the ratchet member 60 is axially biased by a dispensing spring 70 implemented as a compression spring and extending axially between the proximal rim 61 and a reset member 40 that is axially fixed inside the main housing 11 as long as the drive mechanism 8 is in operating mode O.

[0169] In FIGS. 6 and 7 there are shown the sleeve-shaped dose indicator 80 as well as the gauge element 90. The gauge element 90 comprises an elongated and opaque structure with a dose indicating window 91 through which dose indicating numbers of the dose indicator 80 are visible from outside the device. The gauge element 90 is splined to the interior of the main housing 11. It is rotationally locked to the main housing 11 but is free to slide in axial direction relative to the main housing 11. A distal portion of the dose indicator 80 comprises a threaded or helical section 85 that mates and engages a helical section 95 on the inside facing surface portion of the gauge element 90. A rotation of the dose indicator 80 therefore leads to an axial displacement of the gauge element 90. The dose indicator 80 further comprises a zero dose stop 86 as well as a maximum dose stop 87 at axially opposite end sections of the helical section 85. When reaching a minimum or maximum dose configuration the dose indicator 80 with its stops 86, 87 tangentially abuts with correspondingly-shaped stop features of the gauge element 90. In addition the dose indicator 80 comprises a click element 88 to audibly engage with a correspondingly-shaped click element 98 of the gauge element 90 when reaching an initial, hence a zero dose configuration, thereby audibly indicating to a user, that a zero dose configuration, typically at the end of a dispensing procedure has been reached.

[0170] The opaque gauge element 90 is radially sandwiched between the dose indicator 80 and a dose indicating window 16 of the main housing 11 as shown in FIGS. 1, 8 and 9. During a dose setting, in particular during a dose incrementing rotation of the dose indicator 80, the gauge element 90 travels in proximal direction 2, thereby displacing the window 91 to reveal consecutively increasing numbers of the dose indicator 80. At the same time also a distal portion 93 of the gauge element 90 travels in proximal direction 2 which is visible through another window 16a of the main housing 11. The distal portion 93 of the gauge element 90 is of particular use to provide an additional user feedback of the actual dose position of the device. This is of particular use during dose dispensing, namely when the gauge element 90 returns into its distal position as shown in FIG. 8, in which the additional window 16a is completely covered by the gauge element 90. As the gauge element 90 moves in proximal direction during setting of a dose it reveals a further surface underneath as shown in FIG. 9. The axial size of the windows 16, 16a is directly correlated to the maximum size of a dose to be set and dispensed. During the dose dispensing procedure, the progress of dose dispensing is immediately apparent through a comparison of the actual position of the window 91 within the window 16 or by the edge of the distal portion 93 inside the window 16a.

[0171] The axial size of the surface portion 96 as illustrated in FIGS. 9 and 10 is proportional to the dose position of the device and is therefore indicative of the size of the dose currently dialled. The visible surface portion 96 therefore provides an analogue indication or analogue gauge of the size of the dose dialled. As becomes apparent from a comparison of the opposite views of the device according to FIGS. 9 and 10, the additional window 16a may be provided on both sides of the device, which helps to improve overall handling of the device 5 and which helps to improve patient safety.

[0172] The analogue gauge provided by the additional window 16a and the distal portion 93 of the gauge element 90 is of particular use during dispensing of a dose. The number digit display provided by the rotating dose indicator 80 may change too quickly for individual dose position markings to be legible. It may be therefore difficult for the user to estimate the rate at which the dose is actually dispensed and the amount of medicament still to be dispensed.

[0173] In the following setting of a dose is described. For setting of a dose a user starts to rotate the dose dial 20 in a dose incrementing direction, e.g. clockwise relative to the housing 10. This causes the dispensing member 30 to rotate since dose dial 20 and dispensing member 30 are in permanent rotational interlock. The rotation of the dispensing member 30 equally transfers to a rotation of the ratchet member 60, which due to the ratchet engagement with the ratchet profile 105 of the drive sleeve 100 starts to shuttle axially every time correspondingly-shaped teeth of the ratchet profiles 65, 105 mutually engage.

[0174] In this way dialling or setting of a dose is accompanied by an audible click sound as well as by the button portion 32 that shuttles back and forth in axial direction. Since the ratchet member 60 is also rotatably locked to the dose indicator 80 when the drive mechanism 8 is in dose setting mode S also the dose indicator 80 starts to rotate in a dose incrementing direction. In this way a sequence of increasing numbers shows up in the window 91 of the gauge element 90 travelling in proximal direction. During dose setting the drive sleeve 100 is rotatably locked to the main housing 11 through the clutch C1 as illustrated in FIG. 3.

[0175] The ratchet member 60 and the dispensing member 30 are biased in proximal direction 2 by means of the dispensing spring 70 extending axially between a radially widened shoulder 46 of the reset member 40 and a distal end face of the ratchet member 60, in particular a distal end face of the ratchet member's 60 proximal rim 61.

[0176] In this way, since the drive sleeve 100 is rotationally locked and since the dose indicator 80 rotates in a dose incrementing direction the last dose limiter 50 travels in axial direction as the dose indicator 80 is rotated. In case that the amount of medicament left in the cartridge is smaller than the size of the dose to be set the last dose limiter 50 gets in abutment with a stop element on the outer surface of the drive sleeve 100, thereby preventing any further dose incrementing rotation of the dose indicator 80. The dispensing spring 70 is designed to bias the ratchet member 60 onto the distal end face of the drive sleeve. This axial load acts to maintain the mutually corresponding ratchet profiles 65, 105 in engagement.

[0177] A torque required to overhaul the ratchet is governed by the axial load provided by the dispensing spring 70, the ramp angle of the ratchet and the friction coefficient between the mating surfaces and the mean radius of the ratchet profiles 65, 105. As the user rotates the dose dial 20 in a dose incrementing direction, e.g. clockwise, the ratchet member 60 rotates relative to the drive sleeve 100 by consecutive ratchet teeth. Every time a ratchet tooth re-engages into a next detented position an audible click is generated by the mutually engaged ratchet profiles 65, 105. At the same time a tactile feedback is given to the user by the change in torque input required for rotating the dose dial 20.

[0178] For increasing a selected dose, the dose dial 20 is simply rotated further, e.g. in clockwise direction. Every time the dose is incremented by a discreet step the re-engagement of the ratchet profiles 65, 105 provides audible and tactile feedback to the user. If the user continues to increase the dose until a maximum dose limit is reached the dose indicator 80 engages with its maximum dose stop 87 with the gauge element 90 thereby preventing any further rotation of the dose indicator 80 and hence any further rotation of the ratchet member 60, the dispensing member 30 and the dose dial 20.

[0179] Once a dose of respective size has been set or selected the user is also able to de-select or to decrement the dose. De-selecting of a dose is achieved by the user rotating the dose dial 20 in a dose decrementing direction, e.g. counter-clockwise. The torque to be applied to the dose dial 20 is sufficient to overhaul the ratchet between the ratchet member 60 and the drive sleeve 100 in the dose decrementing direction. When the ratchet is overhauled counter-clockwise also the dose indicator rotates in the opposite direction, thereby consecutively illustrating a sequence of decreasing numbers in the window 91. Also the last dose limiter 50 travels in the opposite axial direction towards its initial position.

[0180] Once a dose of required size has been set the drive mechanism 8 may be switched into a dose dispensing mode D by depressing the dispensing member 30 in distal direction 1. When the button portion 32 of the dispensing member 30 is depressed as illustrated for instance in FIG. 5, the ratchet member 60 advances in distal direction 1 against the action of the dispensing spring element 70. The ratchet engagement of the ratchet profiles 65, 105 is disengaged. In addition the clutch C3 between the ratchet member 60 and the dose indicator 80 is disengaged since the ratchet member 60 is displaced axially relative to the dose indicator 80.

[0181] Moreover and due to the axial abutment of dispensing member 30 and drive sleeve 100 also the drive sleeve 100 is displaced in distal direction 1 so that the clutch C1 between drive sleeve 100 and main housing 11 is disengaged or released. Upon axial displacement of the dispensing member 30 a radially widened shoulder portion 35 thereof axially abuts against a correspondingly-shaped shoulder portion 106 of the drive sleeve 100 thereby disengaging the detent structure 102 from the detent structure 18 of the main housing 11 as illustrated in FIG. 5.

[0182] Consequently, the drive sleeve 100 is free to rotate under the action of the mainspring 126. With the distally directed displacement of the drive sleeve 100 also a clutch C2 between drive sleeve 100 and dose indicator 80 is engaged.

[0183] During dose dispensing the drive sleeve 100 then rotates in a dose decrementing direction, e.g.

[0184] counter-clockwise. This rotation is equally transferred to a dose decrementing rotation of the dose indicator 80. Hence, during dose dispensing the dose indicator 80 returns into its initial position and the gauge element 90 returns into its initial position as illustrated in FIG. 1. The process of dose dispensing is terminated when the zero dose stop 86 of the dose indicator 80 abuts with a correspondingly-shaped stop of the gauge element 90.

[0185] There are further provided mutually engaging click elements 88 and 98 on the dose indicator 80 and the gauge element 90 that audibly engage when the zero dose configuration has been reached. The click element 88 may comprise a flexible arm which may be radially outwardly biased by the axial and distal displacement of the ratchet member 60, in particular of its distal rim 62. In this way, the click element 88 of the dose indicator 80 may be radially outwardly biased by the ratchet member 60 when switched into the dose dispensing mode D. In this way, a rather loud and distinct click noise is generated directly indicating to a user, that dose dispensing has terminated.

[0186] The drive sleeve 100 is permanently rotatably engaged via the geared section 103, 113 with the drive member 110. As already explained a rotation of the drive member 110 in dose decrementing direction leads to a distally directed displacement of the piston rod 130. In addition the drive member 110 comprises a radially outwardly protruding click element 112 engaging with a correspondingly-shaped toothed profile on the interior surface of the main housing 11. In this way, delivery of a dose and hence a rotation of the drive member 110 is also accompanied by an audible click sound with each dose increment delivered.

[0187] Delivery and dispensing of a dose continues as described above while the user keeps the dispensing member 30 in a depressed position. If the user releases the dispensing member 30, the dispensing member 30 immediately returns into its initial and proximal dose setting position under the effect of the dispensing spring 70. Consequently, also the ratchet member 60 and the drive sleeve 100 return into their dose setting positions, thereby engaging the clutches C1, C3 but releasing the clutch C2.

[0188] During dose dispensing the dose indicator 80 and the drive sleeve 100 rotate together. Since there is no relative rotation between the drive sleeve 100 and the dose indicator 80 the last dose limiter 50 remains in its axial position relative to the drive sleeve 100 and the dose indicator 80.

[0189] Once the dispensing procedure is stopped by the dose indicator 80 getting in abutment with the gauge element 90 the mainspring-driven rotation of the drive sleeve 100 stops. When the user releases the dispensing member 30, in particular its button portion 32 the drive sleeve 100 will re-engage with the main housing 11 and the ratchet member 60 will re-engage with the dose indicator 80.

[0190] As it is further illustrated in FIGS. 14 and 15 the injection device 5 comprises a bias spring 150 arranged in axial abutment with the proximal end of the cartridge 6 as shown in FIG. 14. The bias spring 150 as shown in FIG. 15 comprises two snap features 151 by way of which the bias spring 150 is axially fixable to the main housing 11. The bias spring 150 further comprises an annular rim 152 that gets in direct axial abutment with a proximal end of the cartridge 6. It is actually the rim 152 that forms or comprises a compression spring element acting in axial direction.

[0191] In this way the bias spring 150 exerts a distally directed bias onto the cartridge 6 which helps to reduce or to remove any detrimental effect arising from geometry tolerances of the cartridge length. Moreover, by means of the bias spring 150 a cartridge removal may be facilitated. Upon releasing and removing of the cartridge holder 140 the cartridge 6 may be axially displaced in distal direction 1 under the effect of the bias spring 150.

[0192] The rim 152 of the bias spring 150 comprises an inner diameter that is larger than the radial extent of a bearing 132 rotatably attached to the distal end of the piston rod 130. The bearing 132 acts as a pressure piece and gets in direct axial abutment with the proximal thrust receiving surface of the piston 7 of the cartridge 6. The bearing 132 is free to rotate with regard to the first axis on the distal end of the piston rod 130. In this way, a rotation of the piston rod 130 during dose dispensing does not transfer to the piston 7 of the cartridge 6.

[0193] The mainspring 126 providing a mechanical energy storage and providing sufficient torque to expel the amount of medicament contained in the cartridge 6 comprises an elongated strip of material that has been rolled or coiled such that its natural state is to form a tightly wound spiral with a comparatively small inner diameter. One end of the elongated material strip is engaged and connected to the drive sleeve 100. The drive sleeve 100 comprises a respective coil portion 107 axially constrained by flange portions 108 as shown in FIG. 11 that allows for a smooth and well-defined coiling of the elongated material strip of the mainspring 126.

[0194] There is further provided a storage spool 120 radially adjacent to the coil portion 107 of the drive sleeve 100. The storage spool 120 is axially intersected by the drive member 110 and is free to rotate on the outer circumference of the drive member 110. Also the storage spool comprises a distal and a proximal flange portion 122 in order to axially constrain the mainspring 126. The mainspring 126, hence the elongated strip of material, tends to coil itself onto the storage spool 120. Since one end of the mainspring 126 is anchored to the drive sleeve 100 the mainspring 126 is chargeable by rotating the drive sleeve 100 in a dose incrementing direction thereby coiling up the elongated strip of material onto the coil portion 107 of the drive sleeve 100. Once charged the majority of material of the mainspring 126 is wrapped around the drive sleeve 100. During consecutive dispense procedures the elongated strip of material transfers back to the storage spool 120 thereby inducing a number of dose decrementing rotations of the drive sleeve 100.

[0195] In the following the reset functionality of the drive mechanism 8 is described. To reset the mechanism and to replace an empty cartridge 6 by a new one the cartridge holder 140 is disconnected from the main housing 11, typically by way of a twisting motion. Such a configuration is shown in FIG. 16, where the cartridge holder 140 and the cartridge 6 have already been removed.

[0196] The cartridge holder 140 as shown in FIGS. 23a-23c comprises a somewhat cylindrical shape with a sidewall portion 147 from which a lock member 144 radially outwardly protrudes. This lock member 144 is provided with a cam portion 145 at a tangential end. A comparison of FIGS. 21 and 22 reveals that the lock member 144 enters a recess 15 adjacent to a distal front face 14 of the main housing 11. As shown in FIG. 22 the lock member 144 and hence the cam portion 145 is axially sandwiched between a distal end 41 of a reset member 40 and the proximally facing inside of the front face 14.

[0197] The reset member 40 is located radially adjacent to the cartridge 6 and also radially adjacent to a receptacle 13 of the main housing 11 that serves to accommodate a major proximal portion of the cartridge 6. By means of twisting the cartridge holder 140 with regard to the first axis 3 and relative to the main housing 11 distal displacement of the reset member 40 is no longer blocked by the lock member 144 and the reset member 40 is allowed to advance in distal direction 1 under the combined action of the dispensing spring 70 and the reset spring 76.

[0198] The reset member comprises a tubular-shaped receptacle that is open towards the distal direction and which accommodates the reset spring 76. One end of the reset spring is attached to a proximally located bottom portion of the receptacle 47 while the oppositely located end of the reset spring 76 is fastened to the front face 14 of the main housing 11. In the present embodiment the reset spring 76 is configured as an extension spring and serves to drag the reset member 40 in distal direction and to bring the reset member 40 in axial abutment with the front face 14 of the main housing 11.

[0199] The axial displacement of the reset member 40 is apparent from a comparison of FIGS. 16 and 17a. Near its distal end the reset member 40 comprises radially outwardly and proximally extending clips 43 that engage with a circumferential groove 89 of the dose indicator 80. In this way, the reset member 40 and the dose indicator 80 are axially engaged. At least one of the clips 43 extending radially outwardly from the tubular-shaped receptacle 47 of the reset member 40 may be splined to the housing and may be axially guided in a correspondingly-shaped groove 19 of the main housing 11 as shown in FIG. 19a.

[0200] In this way the reset member 40 is rotationally locked to the main housing 11. The dose indicator 80 further comprises a detent structure 82, e.g. in form of a crown wheel at its distal front face. This detent structure 82 is configured to engage with a correspondingly-shaped detent structure 17 located at an inside portion of the front face 14 of the main housing 11. As the reset member 40 advances in distal direction 1 the dose indicator 80 experiences a corresponding or equal axial displacement bringing the detent structure 82 and the detent structure 17 in mutual engagement. In this way the dose indicator 80 is rotationally locked to the main housing 11 when the injection device 5 is switched into the reset mode. Hence, a clutch C5 is engaged as indicated in FIG. 18. As a result of the axial displacement of the dose indicator 80, the window 91 of the gauge element 90 advances in distal direction so that it may be no longer visible in the window 16 of the main housing 11, thereby indicating to the user, that a reset procedure is actually in progress.

[0201] The reset member 40 is also selectively axially engageable with the ratchet member 60, in particular with the distal rim 62 of the ratchet member 60. The reset member 40 comprises a distally facing ratchet profile 48 on its outer circumference. The reset member 40 further comprises a receptacle 47 which is open in distal direction and which serves to receive a reset spring 76 as shown in detail in FIG. 4. The distally advancing reset member 40 then axially engages with a correspondingly-shaped ratchet profile 68 of the ratchet member 60, in particular of the distal rim 62 of the ratchet member 60. The ratchet profile 68 faces in proximal direction so as to engage the distally facing corresponding ratchet profile 48 of the reset member 40.

[0202] Once a mutual axial abutment has been reached between reset member 40 and ratchet member 60 as shown for instance in FIG. 17a, a further distally directed displacement of the reset member 40 under the combined action of the dispensing spring 70 and the reset spring 76 leads to a further axial and distal displacement of the ratchet member 60. Since the ratchet member 60 is axially locked to the dispensing member 30 also the dispensing member 30 is moved in distal direction 1 as becomes apparent from a comparison of FIGS. 16 and 18. The button portion 32 of the dispensing member 30 is retracted axially into the main housing 11 and radially flushes with the proximal end of the dose dial 20.

[0203] The distally directed displacement of the dispensing member 30 transfers to a respective distally directed displacement of the drive sleeve 100 so that the clutch C1 disengages without engaging of the clutch C2. Hence, the distally directed displacement of reset member 40, ratchet member 60, dispensing member 30 and drive sleeve 100 is such that the drive sleeve 100 is rotationally disengaged from the main housing 11 but does not engage with the dose indicator 80. A re-engagement of drive sleeve 100 and dose indicator 80 is effectively prevented, since the dose indicator is also moved in distal direction due to its axial engagement with the reset member 40.

[0204] In contrast to the dose dispensing action the dose indicator 80 also travels in distal direction. The distal displacement of the dose indicator in distal direction is even larger than the distal displacement of the ratchet member 60 in distal direction. This is attained through the fact that in operating position 8 as illustrated in FIG. 4 there exists an at least small axial gap between the mutually corresponding ratchet profiles 48, 68 of reset member 40 and ratchet member 60. When reaching the reset position the dose indicator 80 has advanced in distal direction in comparison to the ratchet member 60, thereby disengaging the clutch C3 so that the ratchet member 60 and the dispensing member 30 are free to rotate relative to the dose indicator 80.

[0205] Before the clutch C1 is disengaged a torque-proof clutch C4 as shown in FIG. 17b between dispensing member 30 and drive sleeve 100 is engaged. In this way the dispensing member 30 and hence the dose dial 20 is rotatably locked to the drive sleeve 100. This is not only to prevent an uncontrolled release of mechanical energy from the mainspring 126 upon releasing of the clutch C1 but also to provide a torque-proof engagement between the dose dial 20 and the drive sleeve 100. Activation of the clutch C4 is obtained by means of a head portion 44 located at a distal end of the reset member 40.

[0206] The head portion 44 is located inside the hollow shaft of the dispensing member 30. The head portion 44 is furthermore arranged at a proximal end of the reset member. The reset member 40 comprises a tubular shaped receptacle 47 at its distal end and further has a longitudinal shaft portion 49 extending in proximal direction 2. At the proximal end of the shaft portion 49 the head portion 44 is located protruding radially outwardly from the shaft portion and having at least bevelled or conical surface facing in distal direction 1. The shoulder portion 46 forms a transition between the distal receptacle 47 and the proximal shaft portion 49. The shaft portion 49 further supports and axially intersects the dispensing spring 70.

[0207] Axial displacement of the reset member 40 in distal direction 1 brings the radially widened head 44 in axial and radial abutment with resilient latch elements 33 that extend radially inwardly from an inside facing sidewall portion of the dispensing member's 30 shaft portion 31. Due to the axial distal displacement of the reset member 40 and hence of its head portion 44 relative to the dispensing member 30 at the beginning of the reset member's distally directed displacement the latch elements 33 are urged radially outwardly to engage with correspondingly-shaped recesses 101 provided on the inside facing portion of the hollow drive sleeve 100. In this way a torque-proof and rotational engagement of dispensing member 30 and drive sleeve 100 is obtained.

[0208] In this reset position R as shown in FIG. 18 the dose dial 20 is rotatable in dose incrementing direction, e.g. clockwise. This rotation transfers to the dispensing member 30 and to the ratchet member 60. The ratchet engagement between the ratchet member 60 and the reset member 40 is overhauled when sufficient torque is applied to the dose dial 20. Clockwise and anti-clockwise ramp angles of the ratchet profiles 48, 68 of the reset member 40 and the ratchet member 60 respectively are designed such that the user may rotate the dose dial 20 and hence the dispensing member 30 and the drive sleeve 100 in dose incrementing direction so as to charge the mainspring 126 but that stored spring energy does not cause the drive sleeve 100 to rotate in the opposite direction, hence in dose decrementing direction. Hence, for resetting the dose dial 20 has to be twisted and rotated in the same direction as for increasing a dose in dose setting mode.

[0209] Since the dose indicator 80 is rotationally locked to the main housing 11 and since the drive sleeve 100 rotates in dose decrementing direction the last dose limiter 50 returns into its initial zero dose position. Rotation of the drive sleeve 100 during the reset operating is equally transferred to the drive member 110 thereby inducing a proximally directed retraction and displacement of the piston rod 130. The outer thread 133 of the piston rod is threadedly engaged with a threaded web or flange portion 9 of the main housing 11 as for instance shown in FIG. 20.

[0210] The reset operation terminates when the bearing 132 axially abuts with a stop face 22 of the main housing 11 as shown in FIG. 21.

[0211] In such a configuration a new cartridge 6 can be fitted into the receptacle 13 so that a proximal thrust receiving surface of the cartridge's piston 7 axially abuts with a distal thrust exerting surface of the bearing 132. In addition the cartridge 6 can be axially inserted into the receptacle 13 against the action of the bias spring 150. Once the cartridge 6 has been assembled inside the main housing 11 the cartridge holder 140 can be placed over the distal end of the cartridge 6 and can be locked to the main housing 11 as shown in FIGS. 22-23c.

[0212] The cartridge holder 140 arranged along the first axis 3 is fitted over the distal end of the cartridge 6 so that a radially widened rim of its gripping surface 143 axially abuts in proximal direction 2 against the outside facing portion of the front face 14 of the main housing 11. It is then due to a twisting motion of the cartridge holder 140 that the lock member 144 radially outwardly protruding from a substantially tubular-shaped sidewall portion 147 enters a recess 15 thereby engaging a tilted cam portion 145 with a distal edge 42 of the reset member 40 as shown in FIG. 23b. A further twisting motion of the cartridge holder 140 leads to the configuration as shown in FIG. 23c. The distal edge 42 of the reset member 40 travels along the tilted cam portion 145 until a proximally facing surface of the lock member 144 axially abuts with the distally facing front face 41 of the reset member 40.

[0213] In this way, the twisting motion of the cartridge holder 140 during re-attachment of the cartridge holder 140 to the main housing 11 induces a proximally directed displacement of the reset member 40 against the combined action of the dispensing spring 70 and the reset spring 76 thereby switching the drive mechanism 8 from the reset mode R into the operating mode 0.

[0214] As indicated in FIG. 23b the lock member 144 is arranged at a well-defined axial distance to the radially thickened gripping surface 143. In other words, there is provided an axial gap 146 between the lock member 144 and the gripping surface 143 extending in tangential direction that matches with the axial thickness of the front face 14 of the main housing 11. Upon twisting of the cartridge holder 140 into a locked configuration as shown in FIGS. 22 and 23c the cartridge holder 140 axially engages with the main housing 11, in particular with its front face 14. When the front face 14 enters the axial and tangential slit 146 the cartridge holder 140 is automatically axially fixed and locked to the main housing 11.

[0215] By means of the lock member 144 radially outwardly protruding from the sidewall portion 146 of the cartridge holder 140 a twisting motion of the cartridge holder 140 is transferable to an axial displacement of the reset member 40 which is located radially offset to the cartridge holder 140 and which is arranged in a radially non-overlapping configuration to the cartridge holder 140. A proximally facing abutment surface 148 of the lock member 144 engages and abuts with the distal end face 41 of the reset member 40.

[0216] As the reset member 40 is displaced into its proximal operating position O the drive sleeve 100 returns into its operating position, hence into its dose setting position in which the clutch C1 is engaged. Thereafter, upon a further proximally directed displacement of the reset member 40 the clutch C4 disengages, the dose indicator 80 is rotationally released from the main housing 11 and the ratchet member 60 re-engages with the drive sleeve 100 via the ratchet engagement and further rotationally locks to the dose indicator 80.

[0217] The dispensing spring 70 ensures that the ratchet member 60, the dispensing member 30 and the drive sleeve 100 are displaced axially in proximal direction with regard to the reset member 40.

LIST OF REFERENCE NUMERALS

[0218] 1 distal direction

[0219] 2 proximal direction

[0220] 3 axis

[0221] 4 axis

[0222] 5 injection device

[0223] 6 cartridge

[0224] 7 piston

[0225] 8 drive mechanism

[0226] 9 flange

[0227] 10 housing

[0228] 11 main housing

[0229] 12 proximal housing portion

[0230] 12a socket portion

[0231] 13 receptacle

[0232] 14 front face

[0233] 15 recess

[0234] 16 window

[0235] 16a window

[0236] 17 detent structure

[0237] 18 detent structure

[0238] 19 groove

[0239] 20 dose dial

[0240] 21 clip member

[0241] 22 stop face

[0242] 30 dispensing member

[0243] 31 shaft portion

[0244] 32 button portion

[0245] 33 latch element

[0246] 34 snap member

[0247] 35 shoulder portion

[0248] 40 reset member

[0249] 41 distal end

[0250] 42 distal edge

[0251] 43 clip

[0252] 44 head

[0253] 46 shoulder

[0254] 47 receptacle

[0255] 48 ratchet profile

[0256] 49 shaft portion

[0257] 50 last dose limiter

[0258] 60 ratchet member

[0259] 61 proximal rim

[0260] 62 distal rim

[0261] 63 bridge portion

[0262] 64 toothed profile

[0263] 65 ratchet profile

[0264] 68 ratchet profile

[0265] 70 dispensing spring

[0266] 76 reset spring

[0267] 80 dose indicator

[0268] 81 distal end

[0269] 82 detent structure

[0270] 84 toothed profile

[0271] 85 helical section

[0272] 86 stop

[0273] 87 stop

[0274] 88 click element

[0275] 89 groove

[0276] 90 gauge element

[0277] 91 window

[0278] 93 distal portion

[0279] 95 helical section

[0280] 96 surface portion

[0281] 98 click element

[0282] 100 drive sleeve

[0283] 101 recess

[0284] 102 detent structure

[0285] 103 geared section

[0286] 104 threaded section

[0287] 105 ratchet profile

[0288] 106 shoulder portion

[0289] 107 coil portion

[0290] 108 flange portion

[0291] 110 drive member

[0292] 112 click element

[0293] 113 geared section

[0294] 120 storage spool

[0295] 122 flange portion

[0296] 126 mainspring

[0297] 130 piston rod

[0298] 132 bearing

[0299] 133 outer thread

[0300] 140 cartridge holder

[0301] 141 threaded socket

[0302] 142 through opening

[0303] 143 gripping surface

[0304] 144 lock member

[0305] 145 cam portion

[0306] 146 gap

[0307] 147 sidewall portion

[0308] 148 abutment face

[0309] 150 bias spring

[0310] 151 snap feature

[0311] 152 rim