WO2013078078A1

WO2013078078A1 - Linear drive and clutch assembly

Info

Publication number: WO2013078078A1
Application number: PCT/US2012/065420
Authority: WO
Inventors: Peter Prior; Robbie MULLIGAN
Original assignee: Tech Group Europe Ltd; West Pharmaceutical Services Inc
Current assignee: Tech Group Europe Ltd; West Pharmaceutical Services Inc
Priority date: 2011-11-22
Filing date: 2012-11-16
Publication date: 2013-05-30
Anticipated expiration: 2014-05-22

Abstract

Medical auto-injector with linear drive and clutch assembly comprising a manually tensioned torsion spring (12) as drive element, a lock gear assembly (14) connected to the spring and comprising a sleeve (26) and a gear (24), and a flexible lock ring (16) to engage and disengage the lock gear assembly. The auto-injector further includes a plunger rod (18) engaged with the lock gear sleeve (26) for advancing in a linear direction under the drive force of the spring. The flexible lock ring (16) is axially movable between an initial position in which the lock gear (24) is free to rotate (during dose expelling) and an engaged position for locking the lock gear (assembly) movement in a rotational direction with respect to the main injector housing, such that manual rotation of a proximally located housing section to which the other spring end is connected can serve to tension the spring.

Description

TITLE OF THE INVENTION

[000 lj Linear Drive and Clutch Assembly

BACKGROUND OF THE INVENTION

[0002] The present invention relates to a linear drive and clutch assembly. In particular, the present invention relates to a linear drive assembly having a torsion spring drive element and a gear clutch assembly that engages the torsion spring drive element. The linear drive and clutch assembly selectively provides a linear drive motion or drive force based upon the torsional spring drive element.

[0003] The present invention can be used, for example, in conventional automatic injection syringe devices, commonly referred to as autoinjectors. Typically, in conventional autoinjectors, a relatively large compression spring is used as the drive element for initiating movement of a plunger rod and/or a container within the autoinjector for activating an injection and dispensing a medicament from within the container. Such autoinjectors are also typically single or multiple use disposable autoinjectors that are provided to an end user in a ready-to-use or armed state. That is, conventional autoinjectors are supplied with the drive element e.g., a compression spring, already in a compressed i.e., energized state.

[0004] Conventional autoinjectors (which are mainly manufactured from plastic

components) are also manufactured to have a shelf life which can exceed a five year time period. Thus, conventional autoinjectors maintain their drive elements in a compressed state for extended periods of time. This can be problematic because the drive element, being in an energized state, imparts a biasing force on the various components of the autoinjector during its entire shelf life. Over time, the various components of the autoinjector can be detrimentally affected due to "plastic creep" of the various components of the autoinjector as a result of the biasing force being continuously applied to them. The detrimental effect of plastic creep upon the plastic components is further compounded by the fact that such autoinjector components are manufactured under strict dimensional tolerances, in order for the various plastic components to assemble and operate properly. As a result, slight variations in the dimensions of the various plastic components of conventional autoinjectors can have a significant impact upon the overall allowable tolerances necessary to ensure a properly functioning autoinjector.

[0005] Therefore, a need exists for a linear drive mechanism that can reliably provide a linear drive force, which can be manufactured with greater manufacturing variability, and which docs not stress the internal plastic components of the device itself. Such a need is met by the linear drive and clutch assembly of the present invention.

BRIEF SUMMARY OF THE INVENTION

[0006] In a preferred embodiment, the present invention provides a linear drive and clutch assembly that includes a rotational drive element, a lock gear assembly, a plunger rod, and a flexible lock ring. The rotational drive element provides a force to rotate the lock gear assembly. The plunger rod is slidingly engaged with the lock gear assembly. The flexible lock ring circumscribes the lock gear assembly and is engaged with a housing. The flexible lock ring is also moveable between an initial position disengaged with the lock gear assembly and a second expanded position engaged with the lock gear assembly. In the second expanded position, the lock gear assembly is locked from rotational movement.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0007] The foregoing summary, as well as the following detailed description of a preferred embodiment of the invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there is shown in the drawings an embodiment which is presently preferred. It should be understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown.

[0008] In the drawings:

[0009] Fig. 1 is a partially broken away perspective view of an autoinjector having a linear drive and clutch assembly in accordance with a preferred embodiment of the present invention;

[0010] Fig. la is a greatly enlarged partially broken away perspective view of a proximal region of the autoinjector of Fig. I ;

[0011] Fig. 2 is an exploded perspective view of various components of the linear drive and clutch assembly of Fig. 1 ;

[0012] Fig. 3 is an enlarged perspective view of some of the components of the linear drive and clutch assembly of Fig. 2;

[0013] Fig. 4 is a greatly enlarged top perspective view of a lock gear of the linear drive and clutch assembly of Fig. 1 ;

[0014] Fig. 5 is a bottom perspective view of the lock gear of Fig. 4;

[0015] Fig. 6 is a perspective view of a bearing of the linear drive and clutch assembly of Fig. 1 ;

[0016] Fig. 7 is a cross-sectional perspective view of the bearing of Fig. 6; [0017] Fig. 8 is a perspective view of a bushing of the linear drive and clutch assembly of Fig. 1 ; and

[0018] Fig. 9 is a bottom perspective view of a button housing of the linear drive and clutch assembly of Fig. 1. DETAILED DESCRIPTION OF THE INVENTION

[0019] Reference will now be made in detail to a preferred embodiment of the invention illustrated in the accompanying drawings. Wherever possible, the same or like reference numbers are used throughout the drawings to refer to the same or like features. It should be noted that the drawings are in simplified form and are not drawn to precise scale. In reference to the disclosure herein, for purposes of convenience and clarity only, directional terms such as top, bottom, above, below and diagonal, are used with respect to the accompanying drawings. Such directional terms used in conjunction with the following description of the drawings should not be construed to limit the scope of the invention in any mamier not explicitly set forth. Unless specifically set forth herein, the terms "a," "an" and "the" are not limited to one element but instead should be read as meaning "at least one." The terminology includes the words noted above, derivatives thereof and words of similar import.

[0020] In a preferred embodiment, the present invention provides a linear drive and clutch assembly 10 as embodied in an autoinjector 100, as shown in Figs. 1-9. The linear drive and clutch assembly 10 includes a rotational drive element 12, a lock gear assembly 14, a lock ring 16, a plunger rod 18, a housing 20, and a button housing 22. Fig. 1 illustrates the lock gear and clutch assembly 10 in an assembled configuration while Fig. 2 illustrates the lock gear and clutch assembly 10 in an exploded view. The present linear drive and clutch assembly 10 is described herein as embodied in an autoinjector for exemplary purposes and not by way of limitation. For example, the linear drive and clutch assembly 10 can be applied to any device requiring a linear drive force.

[0021] Referring now to Figs. 1-3, the rotational drive element 12 provides stored

mechanical energy when it is twisted or rotated about a central axis. Preferably the rotational drive element 12 is a torsion spring constructed as a rolled ribbon of spring steel or some other suitable material. The rotational drive element 12 is formed to have an inner end attachable to the lock gear assembly 14 and an outer end attachable to the button housing 22. The rotational drive element 12 is also preferably sized to allow for up to about 10 to 20 complete rotations upon tensioning. More preferably, the rotational drive element 12 is sized to allow for up to about 5 complete rotations, with increments of about 90 degrees of revolution, in order to effectuate a complete linear drive motion.

[0022] The rotational drive element 12 can, for example, be attached to the lock gear assembly 14 at one end (e.g., inner end) and the button housing 12 at an opposite end (e.g., outer end) by folded end segments 12a and 12b, respectively, as shown in Fig. 3. The inner end segment of the rotational drive element 12 is attached to a lock gear 24 of the lock gear assembly 14 by insertion of the folded end segment 12a into an opening 36 (see Fig. 4) of the lock gear 24. The outer end segment of the rotational drive element 12 is attached to the button housing 22 by insertion of the folded end segment 12b into an opening 83 (see Fig. 9) of the button housing 22.

[0023] Referring now to Figs. 1-5, the lock gear assembly 14 includes the lock gear 24, a lock gear sleeve 26, a lead screw nut (not shown), and a lock nut 30. The lock gear 24 includes a substantially hollow body 32 and a radially outwardly extending planar member 34 extending from a distal end of the body 32, as best shown in Fig. 4. The body 32 includes radially outwardly extending generally annular ledges 33a, 33b about its proximal and distal ends forming an annular recess 35 therebetween configured to receive the rotational drive element 12 therein. About a lateral wall of the body 32 within the annular recess 35 is the opening 36 which is configured to receive the inner end segment 12a of the rotational drive element 12. As can be seen in Fig. 1, when the rotational drive element 12 is assembled to the lock gear 24, the annular recess 35 is sized to facilitate retention and positioning of the rotational drive element 12.

[0024] Referring now to Figs. 4 and 5, the planar member 34 has a substantially flat proximally facing surface 34a and an indented annular shoulder 37 extending distally from the substantially flat proximally facing surface 34a. The indented shoulder 37 has an overall diameter that is slightly smaller than the overall diameter of the substantially flat proximally facing surface 34a, and an axial through hole 39 (Fig. 5) that is coaxial with the hollow body 32. A plurality of splines 38 extending in the axial direction are circumferentially and equally spaced apart about the indented shoulder 37. The distal ends of each spline 38 are tapered terminating generally in a crest 38a. As will be described further below, the splines 38 engage the lock ring 16 when the lock ring 16 is moved to an engaged or second position to lock the lock ring 16 in position relative to the button housing 22.

[0025] Referring back to Figs. 1 and 2, the lock gear sleeve 26 includes a substantially tubular body 40 sized to allow and receive the plunger rod 18 to pass therethrough. About a proximal end of the lock gear sleeve 26 are male threads 27 for threadably engaging threads of the lock nut 30, after passing through the lock gear 24. About a midsection of the lock gear sleeve 26 is a generally annular rib 42 extending radially outwardly from the body 40. The rib 42 provides a stop for the assembly of the lock gear sleeve 26 with the lock gear 24.

[0026] The lead screw nut (not shown) is connected to a distal end of the lock gear sleeve 26, for example, by an adhesive or ultrasonic welding. Female threads are configured about the interior surface of the lead screw nut for correspondingly engaging male threads on the plunger rod 18 to drive the plunger rod 18 in an axial direction, as further described below. As will be appreciated by one of ordinary skill in the art, the lock gear and clutch assembly 10 is adapted to be used with conventional plunger drive components well known in the art, such as the lead screw nut (not shown).

[0027] The lock gear assembly 14 has been described with respect to the lock gear 24, lock gear sleeve 26, lead screw nut and lock nut 30, as separate components to be assembled together. However, the foregoing lock gear 24, lock gear sleeve 26 and lead screw nut are preferably formed as a single piece, integrally formed component. When formed as an integral component, the lock nut 30 is not necessary for comprising the lock gear assembly 14.

[0028] Referring now to Fig. 1 a, the plunger rod 18 is generally elongated and has a proximal end and a distal end. The plunger rod 18 includes male threads 44 that engage corresponding female threads of the lead screw nut. Optionally, one or more axially extending splines (not shown) are configured to extend along a majority of the external axial length of the plunger rod 18.

[0029] Referring now to Figs, la, 2, 6 and 7, a bearing 50 is provided to seat on top of the ridge 42 of the lock gear sleeve 26. The bearing 50 includes an inner cylindrical member 52 and an outer cylindrical member 54, along with a plurality of ball bearings 56 in between the outer and inner cylindrical members 52, 54 that reside within a race formed by facing cavities in the inner and outer cylindrical members 52, 54. The bearing 50 facilitates rotational movement of the lock gear sleeve 26 relative to a stationary bushing 58.

[0030] The bearing 50 can be an optional component of the linear drive and clutch assembly 10. In such a configuration, the space occupied by the bearing 50 can be replaced by material from the lock gear sleeve 26 and/or the bushing 58, as further discussed below.

[0031] Referring now to Figs. 1, la, 2 and 8, assembled over the bearing 50 is the bushing 58. The bushing 58 is substantially of an annular configuration that includes a hollow body 59 having an inwardly extending annular flange 60 about its proximal end for engaging a proximal surface of the bearing 50. The outer surface of the hollow body 59 is configured to have a frustroconical shape, such that the outer surface tapers radially outwardly in the proximal direction. The bushing 58 also includes one or more latching members 62 extending distally from the hollow body 59 for latching onto the housing 20 in an assembled state (see Fig. 1). Preferably, the bushing 58 includes four latching members 62 circumferentially and equally spaced apart. Additionally, the bushing 58 includes one or more releasable detents 59a, such as e.g., bumps (Fig. 8), to releasably retain the lock ring 16 in the expanded or second position, as described in more detail below.

[0032] Referring now to Figs. 1-3, the housing 20 is generally configured as a substantially cylindrical housing for receiving a portion of the linear drive and clutch assembly 10 therein. The housing 20 includes a substantially tubular and proximally extending portion 64 having a plurality of axially extending slots 66 (Fig. 2) circumferentially and equally spaced apart. The extending portion 64 is spaced radially inwardly from the exterior lateral surface of the housing 20 such that a radially outwardly extending annular surface 20a facing in the proximal direction is provided. As will be further described below, the radially outwardly extending surface 20a is configured to allow for the lock ring 16 to seat thereon. In addition, the housing 20 includes a radially inwardly extending flange member 67 configured for engaging the latching members 62 of the bushing 58. The flange member 67 can be configured as circular flange member or a partial arc shaped flange member. The foregoing housing 20, bushing 58 and bearing 50 have been described as separate components, however, the bushing 58, housing 20 and bearing 50, or combinations thereof, can optionally be formed as one or more integrally formed components.

[0033] Referring back to Figs. 1, 1a, and 3 to assemble the linear drive and clutch assembly 10, the plunger rod 18 is inserted into the lock gear sleeve 26 and threaded through the lead screw nut. Then, the lock ring 16 is assembled onto the housing 20 circumscribing the flange 64, such that the lock ring splines 72 slide within the slots 66. Thereafter, the bearing 50 is assembled onto the proximal end of the lock gear sleeve 26 followed by the bushing 58 and the lock gear 24. Afterwards, the rotational drive element 12 is attached to the opening 36 of the lock gear 24, as described above and the entire assembly is secured in place by the lock nut 30. The lock nut 30 engages the proximal threads of the lock gear sleeve 26 to securely hold the bearing 50, bushing 58, and lock gear 24 in place. Lastly, the button housing 22 is assembled to cover the proximal end of the lock gear assembly 14 and attached to the lock ring 16 (as further described below) and rotational drive element 12, as shown in Fig. 1.

[0034] Referring now to Figs. 2, 3 and 9, the lock ring 16 is a flexible ring-shaped locking element that includes a plurality of alternating curved segments 70 and substantially planar segments 71 forming the links of the lock ring 16. The curved segments 70 also each include a radially inwardly extending flange 74 that extends in the axial direction. Being formed out of a pliable or flexible, yet durable polymeric material (plastic), the curved segments 70 allow the lock ring 16 to move between a first retracted position (shown in Figs. 2 and 3) having a first overall diameter to a second expanded position (not shown) having a second overall diameter that is larger than the first overall diameter. That is, the lock ring 16 is a flexible locking ring that can expand from its initial retracted position to an expanded position due to the flexible nature of the curved segments 70. Preferably, the lock ring 16 includes six (6) curved segments that are circumferentially and equally spaced apart.

[0035] The planar segments 71 each include a radially inwardly extending spine 72. The splines 72 extend in the axial direction and extend further inwardly about its distal end relative to its proximal end so as to have a slight taper. The tapered splines 72 engage and slide along the frustro conical outer surface of the bushing 58 such that as the lock ring 16 moves in the proximal direction the splines 72 slidingly engage with the outer surface of the bushing 58 to cause the lock ring 16 to move to its expanded position.

[0036] The lock ring 16 also includes a plurality of substantially horizontal slots 76 extending through the lateral sides of the lock ring 16 for engaging an annular flange 80 of the button housing 22 (Fig. 9). This engagement between the slots 76 and annular flange 80 retains the lock ring 16 on the button housing 22. When assembled on the button housing 22, the curved segments 70 of the lock ring 16 are engagable with a plurality of ratcheting bumps 81 formed about the inner circumference of the button housing 22 above and below the annular flange 80. Engagement between the lock ring 16 and ratcheting bumps 81 to retain the liner drive and clutch assembly 10 in a static position when the rotational drive element 12 is energized occurs when the lock ring 16 is pulled proximally to its expanded position, as further discussed below. The lock ring 16 is moved to and maintained in the expanded position as it slides upon the outer tapered surface of the bearing hollow body 59. Rotation of the button housing 22 relative to the lock ring 16, when the lock ring 16 is in the expanded position and engaged with the lock gear 24 (i.e., shifted in the proximal direction by a user), can only occur by application of a rotational force on the button housing 22 by a user. Such rotational force necessary to ratchet the button housing 22 relative to the lock ring 16 is greater than any rotational force supplied by the rotational drive element 12.

[0037] The lock ring 16 slides on/engages the housing 20 by aligning the splines 72 with the slots 66 of the housing 20. The radially inwardly extending tapered splines 72 remain within the slots 66 at all times, thereby assuring that the lock ring 16 does not rotate. The lock ring 16, however, does move in the axial direction to a position slightly spaced from the housing's radially outwardly extending surface 20a. However, due to the taper of the flange 72 about its distal end, as the lock ring 16 is expanded and spaced axially from the housing 22, the flange 72 remains within the slot 66.

[0038] Preferably, the lock ring 16 is formed from a high temperature, durable and pliable polymeric material or plastic. More preferably, the plastic is polyetheretherketone (PEEK), polyphenylene sulfide (PPS) and the like.

[0039] One of the key advantages of the present invention is that the linear drive and clutch assembly 10 is provided to an end user in an initial position with the rotational drive element 12 in an unenergized state or a partially energized state (e.g., a preloaded state of about 3

revolutions of the rotational drive element 12). As a result, the autoinjector 100 having the linear drive and clutch assembly 10 is not subjected to a substantial biasing force generated by a fully energized rotational drive element 12 during its shelf life.

[0040] In the fully assembled configuration, the lock ring 16 is in the retracted, unexpanded or relaxed position/state. To then energize or fully energize the linear drive and clutch assembly 10 a user pulls on the button housing 22 in the proximal direction, which causes the lock ring 16 to move in the proximal direction and slidingly engage with the bushing 58. As the lock ring 16 engages the bushing 58, owing to the expanding taper on the bushing 58, the lock ring 16 is moved to its expanded position thereby allowing the lock ring 16 to engage with the splines 38 of the lock gear 24. That is, the splines 72 and flanges 74 of the lock ring 16 are positioned between the splines 38 on the lock gear 24 to prevent the lock gear 24 from rotating. The lock ring 16 and button housing 22 are held in the second or expanded position owing to the detents 59a on the bushing 58. Then, the user rotates the button housing 22 to energize the drive element 12 to the desired extent, while the lock gear sleeve 26 is being held stationary by the engagement of the lock ring 16 with the lock gear 24. After the rotational drive element 12 is fully energized, the linear drive and clutch assembly 10 is ready to be activated. The fully energized rotational drive element 12 is held in position and prevented from unwinding due to the engagement of the lock ring 16 with the ratcheting bumps 81 on the button housing 22.

[0041] In other words, when the lock ring 16 is in the initial position, the splines 76 are positioned within the slots 66 of the housing 20. Then, when the user activates the device and pulls on the button housing 22, the lock ring 16 and button housing 22 are moved in the proximal direction a fixed amount, e.g., about 1.0 to 2.0 mm and preferably about 1.5 mm, to a second or expanded position. In moving the lock ring 16 in the proximal direction to the second position, the splines 72 and flanges 74 engage the splines 38 of the lock gear 24. In the second position, the splines 72 of the lock ring are engaged with both the splines 38 of the lock gear 24 and the slot 66 of the housing 20. As such, the lock gear 24 is prevented from rotating relative to the housing 20 or otherwise locked from rotating.

[0042] Then, to activate the linear drive and clutch assembly 10, a user depresses the button housing 22 to move the button housing 22 and lock ring 16 distally until the lock ring 16 abuts the housing 20 (i.e., back to the initial position). This causes disengagement of the lock ring 16 from the lock gear 24 and allows the lock gear 24 and lock gear sleeve 26 to rotate as a result of the drive force supplied by the rotational drive element 12. As the lock gear assembly 14 rotates, due to the engagement of the lead screw nut with the plunger rod 18, the plunger rod 18 moves in the distal direction as a result of its threaded engagement with the lead screw nut.

[0043] Referring back to Figs. 1 and la, the autoinjector 100 further includes a distal housing 102, and a vial housing 104 slidingly received within the distal housing 102. Within the vial housing 104 is a container or vial 106 for storing a medicament, as well known in the art. The container 106 includes a distal end configured to attach to a needle hub assembly (not shown), in a manner well known in the art. The autoinjector 100 also includes a piston assembly 107 having a piston 108. The piston 108 is preferably an elastomeric piston, as commonly known in the art.

[0044] In operation, the piston assembly 107 operates similar to any conventional piston of a syringe or medicament containing container that operates to expel fluid from within the container. However, the present autoinjector 100 is preferably configured as a reusable assembly such that the piston assembly 107 and linear drive and clutch assembly 10 can be reused with another vial in a subsequent injection. This can be accomplished by removing the piston assembly 107 from the vial 106 after use. Upon removal of the piston assembly 107, drive components are moved away from engagement with the plunger rod 18 to allow the plunger rod 18 to freely rotate. Then to re-position the plunger rod 18 within the lock gear sleeve 26 a user pushes the piston assembly 107 in the proximal direction which causes the piston rod 18 to move proximally while the lock gear assembly 14 rotates, owing to the engagement of the piston rod threads 44 with the lead nut screw threads. Operation of the autoinjector 100 can then function as previously described above.

[0045] It will be appreciated by those skilled in the art that changes could be made to the embodiment described above without departing from the broad inventive concept thereof. It is understood, therefore, that this invention is not limited to the particular embodiment disclosed, but it is intended to cover modifications within the spirit and scope of the present invention as defined by the invention described above and by the appended claims.

Claims

CLAIMS What is claimed is:

1. A linear drive and clutch assembly comprising:

(a) a first housing;

(b) a rotational drive element;

(c) a lock gear assembly engageable with the rotational drive element and having a lock gear and a lock gear sleeve, at least a portion of the lock gear assembly being disposed within the first housing;

(d) a plunger rod engaged with the lock gear sleeve and configured to advance in a linear direction under a drive force of the rotational drive element; and

(e) a flexible lock ring movable in the linear direction between an initial position and an engaged position, wherein when the flexible lock ring is in the initial position, the lock gear assembly is free to rotate with respect to the first housing, and when the flexible lock ring is in the engaged position, the flexible lock ring prevents rotation of the lock gear assembly with respect to the first housing.

2. The linear drive and clutch assembly of claim 1, wherein the flexible lock ring includes at least one spline extending radially inwardly.

3. The linear drive and clutch assembly of claim 2, further comprising a bushing coupled to the first housing and having a tapered outer surface and at least one releasable detent.

4. The linear drive and clutch assembly of claim 3, wherein when the flexible lock ring is in the engaged position, the at least one spline of the flexible lock ring engages the at least one detent of the bushing.

5. The linear drive and clutch assembly of claim 2, wherein the first housing includes at least one axially extending slot, and wherein when the lock ring is in the initial position, the at least one spline engages the at least one axially extending slot of the first housing.

6. The linear drive and clutch assembly of claim 1 , wherein the rotational drive element includes a first end attached to the lock gear assembly and a second end attached to a second housing.

7. The linear drive and clutch assembly of claim 6, wherein the first end is a folded end segment inserted into an opening of the lock gear.

8. The linear drive and clutch assembly of claim 7, wherein the second end is a folded end segment inserted into an opening of the second housing.

9. The linear drive and clutch assembly of claim 1 , wherein the flexible lock ring includes a plurality of slots formed in the outer periphery thereof.

10. The linear drive and clutch assembly of claim 9, wherein the second housing includes a plurality of ratcheting bumps formed on an inner surface thereof, the ratcheting bumps releasably engaging respective ones of the plurality of slots when the flexible lock ring is in the engaged position.

11. The linear drive and clutch assembly of claim 1 , wherein the flexible lock ring is made from a polymeric material.

12. The linear drive and clutch assembly of claim 1 1, wherein the flexible lock ring is one of polyetheretherketone (PEEK) or polyphenylene sulfide (PPS).

13. The linear drive and clutch assembly of claim 1 , wherein when the flexible lock ring is in the initial position, the second housing is a first distance from the first housing and when the flexible lock ring is in the engaged position, the second housing is a second distance from the first housing, the second distance being greater than the first distance.

14. The linear drive and clutch assembly of claim 1, wherein the flexible lock ring has a first diameter in the initial position and a second diameter in the engaged position, the second diameter being greater than the first diameter.

15. The linear drive and clutch assembly of claim 1 , wherein the second housing rotatably coupled to the first housing.

16. The linear drive and clutch assembly of claim 1 , wherein the rotational drive element is a torsion spring constructed as a rolled ribbon of spring steel.

An autoinjector syringe comprising the linear drive and clutch assembly of claim