Automatic injection device for automatically injecting product into injection site

Abstract

The automatic injection device (1) comprises a housing (10) extending along a longitudinal axis A and configured to receive a medical container (100) having a cartridge (101) defining a reservoir for containing a medical product, said cartridge (101) having a distal end provided with an injection needle and an open proximal end (103) configured to receive a plunger rod (20) for pushing a stopper (105) arranged within the cartridge (101). A needle cover (40) is coupled to the housing (10) and is axially movable relative to the housing between a first extended position, a retracted position, and a second extended position. The plunger rod (20) is axially movable within the housing (10) between an initial position and an end-of-injection position, the plunger rod (20) being configured to urge the stopper (105) to expel the medical product when moved from the initial position to the end-of-injection position. The automatic injection device (1) further comprises: a biasing member for biasing the plunger rod (20) in the distal direction towards the injection end position; and a holder (6) for maintaining the plunger rod (20) in the initial position against the action of the biasing member, the holder (6) comprising an elastic blocking member (7) that is radially deformable between a blocking position for blocking the plunger rod (20) in the initial position and a release position allowing movement of the plunger rod (20) in the distal direction. A locking ring (8) is coupled with the resilient blocking member and is axially movable relative to the resilient blocking member between a locked position for maintaining the resilient blocking member (7) in the blocking position and an unlocked position, axial movement of the locking ring (8) from the locked position to the unlocked position being caused by movement of the needle cover (40) from the first extended position to the retracted position.

Description

Technical Field

[0001] The present invention relates to an automatic injection device.

[0002] In this application, the distal end of a component or device should be understood as the end farthest from the user's hand, and the proximal end should be understood as the end closest to the user's hand. Similarly, in this application, the "distal direction" should be understood as the direction away from the user's hand, and the "proximal direction" should be understood as the direction toward the user's hand. Background Art

[0003] The automatic injection device is designed for automatically injecting a medical product into an injection site. The automatic injection device generally comprises a housing for receiving a medical container. The medical container has a barrel defining a reservoir for containing the medical product, the barrel having a distal end provided with an injection needle and an open proximal end receiving a plunger rod for pushing the stopper. The proximal end of the opening is generally provided with a flange.

[0004] The automatic injection device also includes a safety guard mechanism that moves from an extended position to a retracted position to respectively shield or reveal the needle and an injection mechanism for automatically injecting the drug into the injection site. The injection mechanism generally includes a plunger rod for pushing the stopper in the barrel of the medical container, and an initially compressed spring for moving the plunger in a distal direction. A locking member is provided for holding the plunger rod in an initial position, in which the plunger rod is axially blocked despite the action of the compressed spring. The release member is generally arranged to release the plunger from the locking member and allow the spring to push the plunger rod in a distal direction to implement the injection. The safety guard mechanism needs to be pre-shifted toward the retracted position to allow the release member to unlock the locking member and release the plunger rod.

[0005] Document EP2921191 discloses a device for automatically injecting a medical product into an injection site. The device comprises a two-part assembly having an upper subassembly assembled to a lower subassembly. The lower subassembly receives a syringe provided with an injection needle. The injection needle is covered by a rigid needle guard. The device also comprises a needle cover movable between an extended position and a retracted position relative to the housing. The plunger rod is coupled to a compressed spring and is held in an initial position by a deflectable retainer of an inner cylinder. A button is arranged at the proximal end of the device for releasing the plunger rod by deflecting the retainer outwardly. It is only possible to activate the button when the needle cover moves a predetermined distance in the proximal direction toward the retracted position. In addition, activation of the button requires the end user to press the button. That is, the end user must perform a specific additional operation to activate the device. In addition, the operation may not be so easy because the end user must simultaneously exert a distal force on the button and keep the automatic injection device pressed against his / her skin.

[0006] Document US2021125536 discloses a power unit used in an automatic injection device. Document US2021121633 discloses a drug delivery device, which includes a housing, a drug storage container, a plunger, and a container holder configured to support the drug storage container. Document US2020164456 discloses an automatic injection device, which includes a housing, a syringe carrier, a plunger, and a drive spring.

[0007] Therefore, there is a need for an automatic injection device that allows activation of the injection mechanism without requiring additional action by the end user.

[0008] In addition, in some prior art automatic injection devices, the retainer holding the plunger rod may creep over time under the stress of the compressed spring. Therefore, there is also a need for an automatic injection device that is less sensitive to material creep during long-term storage. Summary of the invention

[0009] One aspect of the present invention is an automatic injection device for automatically injecting a product into an injection site, the automatic injection device comprising:

[0010] a housing extending along a longitudinal axis A and configured to receive a medical container having a barrel defining a reservoir for containing a medical product, the barrel having a distal end provided with an injection needle and an open proximal end configured to receive a plunger rod for pushing a stopper arranged in the barrel;

[0011] a needle cover coupled to the housing and axially movable relative to the housing between a first extended position in which the needle cover at least partially shields the injection needle, a retracted position in which the needle cover is moved proximally relative to the housing, and a second extended position in which the needle cover is moved back in a distal direction to shield the injection needle;

[0012] a plunger rod axially movable within the housing between an initial position and an injection end position distally located relative to the initial position, the plunger rod being configured to push the stopper to expel the medical product when moving from the initial position to the injection end position;

[0013] a biasing member for biasing the plunger rod in a distal direction toward an end-of-injection position;

[0014] a retainer for maintaining the plunger rod in an initial position against the action of the biasing member, the retainer comprising an elastic blocking member which is radially deformable between a blocking position and a release position, in which the elastic blocking member axially abuts against a distal abutment surface of the plunger rod for blocking the plunger rod in the initial position, and in which the elastic blocking member is away from the distal abutment surface of the plunger rod to allow the plunger rod to move in a distal direction;

[0015] A locking ring is connected to the elastic blocking member and can be axially moved relative to the elastic blocking member between a locked position and an unlocked position, in which the locking ring radially abuts against a lateral blocking surface of the elastic blocking member to maintain the elastic blocking member in the blocking position, and in the unlocked position, the locking ring axially moves away from the lateral blocking surface of the elastic blocking member, the axial movement of the locking ring from the locked position to the unlocked position being caused by the needle cover moving from the first extended position to the retracted position.

[0016] The automatic injection device of the present invention allows for easier activation of the injection mechanism. In fact, there is no need to manually press the button, as it has been replaced by a slidable locking ring that automatically moves to the unlocked position when the needle cover is moved to the retracted position. The end user does not need to perform additional operations, the locking ring slides automatically because the needle cover is pressed against the user's skin.

[0017] The automatic injection device of the present invention may also include some or all of the following features.

[0018] In one embodiment, the needle cover has a push surface configured to abut against a distal abutment surface of the locking ring so as to move the locking ring into the unlocked position when the needle cover is moved towards the retracted position. Thus, the needle cover abuts directly against the locking ring without any intermediate components. Activation of the automatic injection device becomes easier for the user.

[0019] In one embodiment, before the automatic injection device is used, the push surface of the needle cover and the distal abutment surface of the locking ring are axially spaced a certain distance from each other, that is, when the needle cover is in the first extended position and the locking ring is in the locked position, there is an axial gap between the push surface of the needle cover and the proximal abutment surface of the locking ring.

[0020] In one embodiment, the blocking position of the elastic blocking member is a rest position. That is, the blocking member does not deform in the blocking position, but deforms when it moves to the release position. More specifically, the elastic blocking member extends parallel to the longitudinal axis A in the blocking position, while the elastic blocking member deflects radially in the release position, so that the axial stop of the elastic blocking member moves away from the distal abutment surface of the plunger rod, so that the plunger rod can move in the distal direction under the pressure of the biasing member.

[0021] In one embodiment, the retaining member is an axial sleeve arranged in the housing, and the elastic blocking member is an axially extending elastic blocking leg forming the distal end or the proximal end of the axial sleeve, and the blocking leg includes: an inward radial protrusion, which defines an axial stop member for abutting against the distal abutment surface of the plunger rod; and a relative outward radial protrusion, which defines a lateral blocking surface for abutting against the locking ring.

[0022] Preferably, the retaining member defines an inner cavity for receiving the plunger rod. The inner cavity may also receive a biasing member. The biasing member may be arranged outside or inside the plunger rod.

[0023] Possibly, the holder and the housing are made in one piece.

[0024] Preferably, the locking ring extends around the retaining member.The lateral blocking surface of the resilient blocking member is an outer lateral blocking surface, and the locking ring has a corresponding inner lateral blocking surface for abutting against said outer lateral blocking surface in the locked position.

[0025] In one embodiment, the locking ring includes a proximal portion and a distal portion separated by a distal shoulder portion, and the distal portion has an inner diameter D1 that is larger than an inner diameter D2 of the proximal portion. Therefore, the proximal portion prevents the retainer from deforming outwardly, while the distal portion allows the retainer to deform outwardly. The proximal portion can be configured to receive the elastic blocking member when the locking ring is in the locked position, and the distal portion can be configured to receive the elastic blocking member when the locking ring is in the unlocked position.

[0026] In one embodiment, when the locking ring is in the unlocked position and the elastic blocking member is in the released position, the distal shoulder of the locking ring and the outward radial projection of the elastic blocking member of the retainer are at an axial distance from each other. Therefore, the distal shoulder does not prevent the elastic blocking member from deflecting toward the released position.

[0027] In an embodiment, the outward radial protrusion of the resilient blocking member comprises a proximal stop configured to abut against a distal shoulder of the locking ring for preventing the locking ring from moving back to the blocking position.

[0028] In one embodiment, the locking ring includes one or more axial protective walls, which define a radial space for receiving the elastic barrier member in the release position. The protective wall can form the distal portion of the locking ring. The protective wall avoids interference between the elastic barrier member and other components of the automatic injection device, so that the injection process can be successfully completed. The protective wall can only partially extend in the circumferential direction, that is, the protective wall does not extend completely around the longitudinal axis A. Preferably, the distal abutment surface of the locking ring can be arranged at the distal end of the distal portion (i.e., the protective wall). In addition, the size of the distal portion (protective wall) can be set so that when the elastic barrier member is in the release position and the locking ring is in the unlocked position, the distal end of the locking ring is located distally relative to the distal end of the elastic barrier member. Therefore, the elastic barrier member does not interfere with the needle cover.

[0029] In one embodiment, the locking ring defines: an inner cavity for receiving the retainer, the inner cavity defining a centering surface for sliding against the retainer and guiding the locking ring to move along the longitudinal axis A; and an axial groove, the axial groove defining a lateral blocking surface for blocking the elastic blocking member of the retainer in the blocking position. The inner cavity of the locking ring has: a proximal opening, the proximal opening allows the locking ring to be installed around the retainer; and an opposite distal opening, the opposite distal opening allows the plunger rod to extend therethrough and move toward the injection end position. The inner cavity can be arranged at the proximal portion of the locking ring.

[0030] In one embodiment, the automatic injection device comprises a retaining member for retaining the locking ring assembled to the holder prior to activation of the automatic injection device.

[0031] In one embodiment, the retaining member comprises at least: a first blocking feature for blocking the axial movement of the locking ring in the distal direction; and a second blocking feature for blocking the axial movement of the locking ring in the proximal direction when the proximal force applied to the locking ring is below a predetermined threshold, i.e., before the automatic injection device is activated. When the locking ring is in the locked position, a second abutment portion can be formed by the second point of the locking ring axially abutting against the second stop of the retaining member.

[0032] In a possible embodiment, the inner cavity further comprises an axially extending flexible leg having a blocking feature configured to engage a corresponding blocking feature of the retainer to maintain the locking ring in a locked position when the proximal thrust exerted by the needle cover on the locking ring is below a predetermined threshold. Thus, when the automatic injection device is dropped on the floor with the cap facing upward, the automatic injection device will not be activated. Thus, the connection feature allows passing the drop test.

[0033] In one embodiment, the distal abutment surface of the locking ring is arranged at the distal end of the locking ring, and the push surface of the needle cover is arranged at the proximal end of the needle cover. More specifically, the distal abutment surface of the locking ring can be the most distal surface of the locking ring. Similarly, the push surface of the needle cover can be the most proximal surface of the needle cover.

[0034] In an embodiment, the needle cover has a radial tab engaging with the first slot of the rotatable cam, and the radial tab has a proximal surface at least partially forming a push surface of the needle cover.

[0035] In one embodiment, the locking ring comprises a guide member for preventing the locking ring from rotating about the longitudinal axis A. The guide member may include a groove, which may be arranged on the outer lateral surface of the locking ring for receiving the axial guide rib of the housing. The guide member of the locking ring may be arranged at the proximal portion of the locking ring.

[0036] In an embodiment, the housing comprises a connection piece for fixedly connecting the retaining piece to the housing, the connection piece defining a cutout for receiving the locking ring and a guide track for engaging a guide member of the locking ring. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The present invention and its resulting advantages will become clear from the following detailed description given with reference to the accompanying drawings:

[0038] Figure 1 is an exploded view of an automatic injection device according to an embodiment of the present invention,

[0039] Figure 2A and 2B is a perspective cross-sectional view of a top body of an automatic injection device according to an embodiment of the present invention,

[0040] Figure 3 is a perspective view of a needle cover of an automatic injection device according to an embodiment of the present invention,

[0041] Figure 4A is a perspective view of a locking ring of an automatic injection device according to an embodiment of the present invention,

[0042] Figure 4B is a perspective cross-sectional view of a locking ring of an automatic injection device according to an embodiment of the present invention,

[0043] Figure 4C is a top view of a locking ring of an automatic injection device according to an embodiment of the present invention,

[0044] Figure 5A and 5B is a cross-sectional view of an automatic injection device according to an embodiment of the present invention in a blocking position of a locking ring,

[0045] Fig. 6Aand 6B is a cross-sectional view of an automatic injection device according to an embodiment of the present invention in a released position of a locking ring,

[0046] Fig. 7A and 7B are a cross-sectional view and a perspective view respectively of a plunger rod of an automatic injection device according to an embodiment of the present invention,

[0047] Fig. 8A and 8B are perspective views of a locking ring and a retaining member of an automatic injection device according to an embodiment of the present invention, respectively,

[0048] Fig. 9A is a cross-sectional view of an automatic injection device according to an embodiment of the present invention,

[0049] Fig. 9B is a perspective view of a locking ring of an automatic injection device according to an embodiment of the present invention,

[0050] Fig. 9C is a partial perspective view of a holder of an automatic injection device according to an embodiment of the present invention,

[0051] Fig. 10A is a cross-sectional view of an automatic injection device according to an embodiment of the present invention,

[0052] Fig. 10B is a perspective view of a locking ring and a retaining member of an automatic injection device according to an embodiment of the present invention,

[0053] Fig.11A is a cross-sectional view of an automatic injection device according to an embodiment of the present invention, wherein the locking ring is in a locked position,

[0054] Fig. 11B yes Fig.11A Detail of the automatic injection device.

[0055] Fig. 11C Is from Fig.11A A cross-sectional view of an automatic injection device according to an embodiment of the present invention after being rotated 90°,

[0056] Fig.11D yes Fig. 11C Detailed picture of

[0057] Fig.11E is a cross-section of an automatic injection device according to an embodiment of the present invention, wherein the locking ring is in an unlocked position,

[0058] Fig.11F yes Fig.11E Detailed picture of

[0059] Fig.11G Is from Fig.11FA cross-sectional view of an automatic injection device according to an embodiment of the present invention after being rotated 90°,

[0060] Fig.11H is a perspective view and a partial cross-sectional view of an automatic injection device according to an embodiment of the present invention,

[0061] Fig.11I is a perspective view of a locking ring of an automatic injection device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0062] refer to Figure 1 , shows an automatic injection device 1 according to an embodiment of the present invention. The automatic injection device 1 is designed for automatically injecting a product into an injection site. The automatic injection device 1 extends along a longitudinal axis A. The automatic injection device 1 comprises a housing 10, the housing comprising a top body 11 and a bottom body 12, the top body and the bottom body being assembled with each other by any suitable fixing member (e.g., a snap-fit ​​member).

[0063] The bottom body 12 is configured to receive a medical container 100, such as a syringe, for example a prefilled syringe. The medical container 100 has a tubular barrel 101, which defines a reservoir for containing a medical product to be injected. The barrel 101 has a distal end, which is provided with an injection needle (not shown) and a needle shield 102 removably attached to the distal end for protecting and sealing the injection needle. The barrel 101 has an open proximal end 103, which can be provided with a flange 104 and is configured to receive a plunger rod 20 pushed in a distal direction by an injection spring 30. The plunger rod 20 is configured to push a stopper 105 arranged in the barrel 101, thereby discharging the medical product.

[0064] To this end, the plunger rod 20 can be in the housing 10, in the initial position ( Figure 5A 105. The plunger rod 20 is axially moved between an initial position (or 5B) and an injection end position distally located relative to the initial position. In the initial position, the injection spring 30 is compressed; the distal end 21 of the plunger rod 20 can be axially away from the stopper 105. In the injection end position, the injection spring 30 is extended; the distal end 21 of the plunger rod 20 can press the stopper 105 against the distal end 106 of the reservoir defined by the barrel 101. The movement of the plunger rod 20 from the initial position to the injection end position is caused by the injection spring 30 pushing the plunger rod 20 in the distal direction.

[0065] The plunger rod 20 comprises a distal abutment surface 22 which may be arranged at the distal side of the outer flange 23 for abutting against the axial stop 71, thereby axially blocking the plunger rod 20 in the initial position. The proximal side of the outer flange 23 may serve as a support for the distal end 31 of the injection spring 30. Figures 1 to 6BIn the embodiment shown, the injection spring 30 is external to the plunger rod 20 and extends around the plunger rod 20 .

[0066] The automatic injection device 1 further comprises: a cap 2 removably attached to the distal end 13 of the bottom body 12; a needle cover 40 arranged inside the bottom body 12; a safety spring 3 for pushing the needle cover 40 in the distal direction; and a cam 50 pivotally mounted around the needle cover 40, the cam 50 having a first slot 51 engaged by a radial tab 41 of the needle cover 40 and having a second slot 52 engaged by a ring 4 fixed to the medical container 100, for blocking axial movement of the medical container 100 in the distal direction before activating the automatic injection device 1.

[0067] Figure 3 A needle cover 40 is shown. The needle cover 40 is axially movable along the longitudinal axis A relative to the base body 12 between a first extended position (pre-use position) in which the needle cover 40 at least partially or completely shields the injection needle, a retracted position (injection position) located proximally relative to the first extended position, and a second extended position (safety position) in which the needle cover 40 is moved back in the distal direction to safely shield the injection needle. The needle cover 40 has a distal end 42 designed to be pressed against an injection site, an opposite proximal end 43 defining a push surface 44 (the function of which will be further explained below), and one or more radial tabs 41 for engaging a first slot 51 of a rotatable cam 50. The movement of the needle cover 40 from the first extended position to the retracted position is caused by the user pressing the distal end 42 of the needle cover 40 against the injection site, while the movement of the needle cover 40 from the retracted position to the safety position is caused by the safety spring 3 pushing the needle cover 40 back in the distal direction.

[0068] Figure 2A and 2B The top body 11 is shown. The top body 11 has lateral walls 14, an open distal end 15, and a closed proximal end 16. In the illustrated embodiment, the proximal end 16 of the top body 11 is closed by a top cap 5 fixed to the top body 11. The top cap 5 can be a separate component that can be fixed to the top body 11 by a suitable fixing member (e.g., a snap member), or can be made into an integral piece with the top body 11. Still referring to Figure 2A and 2B, the top body 11 comprises a retainer 6 configured to retain the plunger rod 20 in an initial position before the automatic injection device 1 is activated. The retainer 6 may take the form of a tubular sleeve 60 fixed to the lateral wall 14 by a connection 17. The sleeve 60 and the top body 11 may be made in one piece. Thus, the retainer 6 is fixed relative to the housing 10.

[0069] The tubular sleeve 60 defines an inner cavity 61 for receiving the plunger rod 20 and the injection spring 30. The sleeve 60 includes an open distal end 62, which provides a passage for the plunger rod 20, and an opposite proximal end 63, which may be closed by a transverse wall 64, for providing support for the proximal end 32 of the injection spring 30.

[0070] The distal end 62 of the sleeve 60 has one or more elastic blocking members 7, which may be in the form of axially extending elastic blocking legs 70 for blocking the plunger rod 20 in the initial position. To this end, the blocking legs 70 include axial stops 71 for abutting against the distal abutment surface 22 of the plunger rod 20 in the initial position ( Figure 5A The blocking leg 70 can be in a blocking position (which is a resting position, Figure 5A ) and the release position (which is the deformation position, Figure 6B ), in which the axial stop 71 of the blocking leg axially abuts against the distal abutment surface 22 of the plunger rod 20, and in which the blocking leg 70 is radially deflected outwardly so that the axial stop 71 of the blocking leg moves out of the path of the plunger rod 20. The movement of the blocking leg 70 from the rest position to the deformed position is caused by the injection spring 30 pushing the plunger rod 20 in the distal direction.

[0071] The axial stop 71 of the blocking leg 70 may be arranged at the proximal side of the inward radial protrusion 72, which is preferably located at the distal end 73 of the blocking leg 70. The proximal end 77 of the blocking leg 70 may be fixed to the sleeve 60. The axial stop 71 may be angled relative to the longitudinal axis A so that the plunger rod 20 easily passes over the axial stop 71 when the automatic injection device 1 is activated. The distal abutment surface 22 of the plunger rod 20 may also be angled, or even parallel to the axial stop 71, so that their shapes complement each other. In the embodiment shown, the axial stop 71 and the distal abutment surface 22 have a frustoconical shape.

[0072] Blocking leg 70 can comprise lateral blocking surface 74, and described lateral blocking surface can be limited by outward radial projection 75, is used for abutting on locking ring 8, thereby blocking leg 70 is maintained in its rest position.The lateral blocking surface 74 can be parallel to longitudinal axis A, so that locking ring 8 can slide along proximal direction.Outward radial projection 75 can be arranged to be radially opposite to inward radial projection 72, that is, be in the same level with inward radial projection 72.Outward radial projection 75 is configured to engage with the axial groove 80 of locking ring 8, as shown below.

[0073] The tubular sleeve 60 may include a number of blocking legs 70 regularly distributed in the circumferential direction, such as two diametrically opposed blocking legs 70, although this number may vary. The tubular sleeve 60 may also include one or more axially extending centering legs 65, such as two diametrically opposed centering legs 65, for providing support for the locking ring 8 so that the locking ring 8 can be centered relative to the central longitudinal axis A and can slide along the sleeve 60. The centering legs 65 do not have any inward protrusions and therefore do not hinder the axial movement of the plunger rod 20. The centering legs 65 may include a connecting feature 66, such as a point protruding from the outer side surface 67 of the centering legs 65, for engaging a corresponding connecting feature 81 of the locking ring 8, as will be explained in further detail below. The point may have a rounded shape. The centering legs 65 and the blocking legs 70 may be separated from each other by an axial slit 68, such as Figure 2A Or as shown in 2B.

[0074] Still refer to Figure 2A and 2B , the connector 17 may be in the form of a radial wall extending parallel to the longitudinal axis A. The connector may define: an axial cutout 170 to allow the locking ring 8 to slide therein; and a guide rail 171 in the form of an axial rib, which may extend along the inner surface of the lateral wall 14 of the top body 11 for guiding the proximal movement of the locking ring 8.

[0075] FIG. 4A to FIG. 4C A locking ring 8 is shown. The locking ring 8 is arranged on the retainer 6 for retaining the axial stop 71 of the retainer 6 against the distal abutment surface 22 of the plunger rod 20. Thus, the locking ring 8 helps to retain the plunger rod 20 in the initial position despite the action of the injection spring 30. The needle cover 40 and the locking ring 8 may be separate components. Likewise, the retainer 6 and the locking ring 8 are also separate components.

[0076] The locking ring 8 is coupled to the sleeve 60 and can be in a locked position ( Figure 5A) and an unlocked position located proximally relative to the locked position, in which the lateral blocking surface 82 of the locking ring 8 abuts against the lateral blocking surface 74 of the retaining member 6 to prevent the blocking leg 70 from moving to its release position, and in which the locking ring 8 allows the blocking leg 70 to move to its release position ( Fig. 6A , 6B). The automatic injection device 1 does not have any spring that biases the locking ring 8 in the distal or proximal direction. That is, except for a retaining member that temporarily maintains the locking ring 8 in the locked position and a needle cover 40 configured to push the locking ring 8 in the proximal direction, the locking ring 8 slides freely along the sleeve 60.

[0077] The movement of the locking ring 8 from the locked position to the unlocked position is caused by the push surface 44 of the needle cover 40 abutting against the distal abutment surface 83 of the locking ring 8. This occurs when the needle cover 40 moves toward the retracted position. In order to increase the reliability of the contact between the needle cover 40 and the locking ring 8, the push surface 44 of the needle cover 40 can be at least partially defined by the top (proximal) surface of the radial tab 41, such as Figure 3 That is, the top surface of the radial tab 41 is at the same level as the push surface 44. Preferably, the push surface 44 is the most proximal surface of the needle cover 40 and may be arranged at the proximal ends 45 of the two proximally extending legs 46 of the needle cover 40. The needle cover 40 directly pushes the locking ring 8, i.e., directly contacts the locking ring 8, without any intermediate component to transmit the axial movement of the needle cover 40 to the locking ring 8.

[0078] refer to FIG. 4A to FIG. 4C The distal abutment surface 83 of the locking ring 8 can be arranged at the distal end 840 of one or more (e.g. two diametrically opposite) axially extending protective walls 84. The protective wall 84 is designed to define a radial space 85 for receiving the deformed blocking leg 70 so that the blocking leg does not hinder the movement of other components such as the needle cover 40. The distal abutment surface 83 can be the most distal surface of the locking ring 8. The distal abutment surface 83 of the locking ring 8 can be flat, orthogonal to the longitudinal axis A, and can extend longitudinally in the circumferential direction.

[0079] like Figure 5AAs shown, the needle cover 40 in the first extended position and the locking ring 8 in the locked position may be axially separated by a predetermined axial gap 90. The axial gap 90 allows the assembly of the automatic injection device 1 without the need to push the locking ring 8 with the needle cover 40 during the assembly process. It should be noted that the needle cover 40 directly abuts against the locking ring 8, that is, no intermediate component is required between the needle cover 40 and the locking ring 8. This direct contact allows reducing the force required to trigger the injection and further prevents any axial looseness when activating the automatic injection device 1. The push surface 44 of the needle cover 40 may extend in the circumferential direction separately from the top surface of the tab 41, and the top surface of the tab may define a radial portion of the push surface 44 for ensuring abutment between the needle cover 40 and the locking ring 8.

[0080] Still refer to Figures 4A-4C , the locking ring 8 comprises a tubular wall defining an inner cavity 86 for receiving the retainer 6. The inner cavity 86 leads to a proximal opening 861 allowing the insertion of the retainer 6 and to an opposite distal opening 862 providing a passage for the plunger rod 20 to move toward the end-of-injection position. The inner side of the tubular wall may define one or more centering surfaces 87, such as two diametrically opposed centering surfaces 87, whose shape is complementary to the centering legs 65 of the retainer 6, so as to correctly position the locking ring 8 relative to the longitudinal axis A during the assembly process of the automatic injection device 1. The tubular wall also defines one or more (e.g. two) diametrically opposed axial grooves 80, the bottom of which defines the lateral blocking surface 82 of the locking ring 8. Therefore, the shape of the axial groove 80 is arranged to receive the outward radial protrusion 75 of the blocking leg 70 and allow the locking ring 8 to translate along the blocking leg 70. The diameter D2 defined between the lateral blocking surfaces 82 is smaller than the diameter D1 between the two protective walls 84. Furthermore, the axial length of the distal portion of the locking ring 8 (protective wall 84 ) may be shorter than the axial length of the proximal portion of the locking ring 8 (tubular wall 86 ).

[0081] The automatic injection device 1 may include a maintaining member for temporarily maintaining the locking ring 8 in the locked position before using the automatic injection device 1. The maintaining member may be configured to release the locking ring 8 so that once a predetermined proximal force is applied on the locking ring 8 (via the needle cover 40), the locking ring 8 moves from the locked position to the unlocked position.

[0082] exist Figures 4A-4C and Figure 5B In the illustrated embodiment, the maintaining member includes: a first blocking feature 660, 810 for blocking the axial movement of the locking ring 8 in the distal direction; and a second blocking feature 661, 811 for blocking the axial movement of the locking ring 8 in the proximal direction when the proximal force applied to the locking ring 8 is lower than a predetermined threshold.

[0083] More specifically, the first blocking feature comprises one proximal protrusion or first point 810 and a proximal side or first stop 660 of the protrusion 66 of the retainer 6. The second blocking feature comprises two distal protrusions or second points 811 and a distal side or second stop 661 of the protrusion 66 of the retainer 6. The first point 810 and the second point 811 may be offset from each other in the circumferential direction; they do not face each other in the axial direction and may therefore form the vertices of a triangle. These blocking features 66, 81 form snap or clamping members for removably fixing the locking ring 8 to the retainer 6. That is, before the automatic injection device 1 is activated, the blocking features 66, 81 temporarily maintain the locking ring 8, which is in the locked position, assembled to the retainer 6.

[0084] More specifically, the first dot 810 prevents the removal of the locking ring 8 and the retaining member 6, while the second dot 811 prevents the locking ring 8 from moving to the unlocked position, for example when the automatic injection device 1 falls on the floor (e.g. during a "cap up" drop test). Thus, the second dot 811 prevents the automatic injection device 1 from being accidentally activated. However, the blocking feature 81 of the locking ring 8 and the blocking feature 66 of the retaining member 6 are configured to disengage when the needle cover 40 pushes against the locking ring 8 during use of the automatic injection device 1. To this end, the dots 810, 811 may have a rounded shape. In addition, the second dot 811 may also be arranged to abut against the blocking structure 66 of the retaining member 6 when the locking ring 8 is in the locked position. Thus, when the needle cover 40 abuts against the locking ring 8, i.e., once the needle cover 40 begins to push the locking ring 8 away from the locked position, the user will feel a resistance. This resistance informs the user that further pushing the automatic injection device 1 against the injection site will trigger the device and the injection process. This also helps prevent the autoinjector 1 from being activated during a drop test.

[0085] In addition, the locking ring 8 may include an axially extending flexible leg 88, and the blocking feature 81 of the locking ring 8 may be arranged on the axially extending flexible leg 88. The flexible leg 88 is configured to deflect radially outward so that the second point 811 can pass over the blocking feature 66 of the retainer 6. The flexible leg 88 may have a fixed proximal end 880 and an opposite free distal end 881. Figure 4C As can be seen, the flexible legs 88 can be arranged in the axial recess 883. The locking ring 8 can include one or more (e.g., two diametrically opposed) flexible legs 88. The diameter D3 between the flexible legs 88 can be greater than the diameter D4 between the centering surfaces 87 and less than the diameter D2 between the lateral blocking surfaces 82 of the locking ring 8.

[0086] The lock ring 8 cannot rotate around the longitudinal axis A and can only move in the axial direction. The lock ring 8 also includes a guide member 89 in the form of an axially extending guide groove defined by two axial ribs 890 protruding from the outer side of the lateral wall 86 of the lock ring 8, for guiding the sliding of the lock ring 8 relative to the sleeve 60 and the top body 11. The guide member 89 also prevents the lock ring 8 from rotating around the longitudinal axis A. The groove 89 is configured to engage with the axial rib 171 of the connector 17 of the top body 11. The lock ring 8 includes one or more guide members 89, such as Figure 4C As shown, two diametrically opposed guide members 89. The groove may have an open proximal end and a distal end closed by a radial flange 890 of the locking ring 8.

[0087] The lateral wall 86 is arranged proximally of the protective wall 84 of the locking ring 8, so that the lateral wall 86 can form a proximal portion of the locking ring 8, while the protective wall 84 can form a distal portion of the locking ring 8. The lateral wall 86 and the protective wall 84 can be separated by a radial flange 890 defining a distal shoulder 891. In the unlocked position, the distal shoulder 891 of the locking ring 8 can be axially away from the outward radial protrusion 75 of the retaining member 6, as shown in FIG. Figure 6B As shown, the distal shoulder 891 does not hinder the blocking leg 70 from moving toward its release (deformed) position. More specifically, the distal shoulder 891 is axially away from the proximal stop 76, which is defined at the proximal side of the outward radial protrusion 75 of the blocking leg 70. The proximal stop 76 is configured to abut against the distal shoulder 891 of the locking ring 8 to prevent the locking ring 8 from moving back to the blocking position when the needle cover 40 moves away from the locking ring 8 toward the safety position.

[0088] Figure 7A-7B There is shown a plunger rod 20 according to another embodiment of the automatic injection device 1. Similar features to other embodiments are indicated by the same reference numerals. Figure 7A-7B The plunger rod 20 is similar to Figure 1 A-6B plunger rod 20, except that the injection spring 30 is arranged in the inner cavity 24 of the plunger rod 20. The distal end 31 of the injection spring 30 can abut against the distal end 240 of the inner cavity 24 of the plunger rod 20. The distal abutment surface 22 of the plunger rod 20 is arranged at the distal side of the radial window 25 here. The plunger rod 20 may include two radial windows 25 that are diametrically opposed. The shape of the inward radial protrusion 72 of the blocking leg 70 is designed to engage with the radial window 25 of the plunger rod 20.

[0089] FIG. 8A to FIG. 8BA retaining member and a holder 6 of a locking ring 8 according to another embodiment are shown. The retaining member comprises: a first blocking feature 660, 810 for blocking the axial movement of the locking ring 8 in the distal direction; and a second blocking feature 661, 811 for blocking the axial movement of the locking ring 8 in the proximal direction when the proximal force applied to the locking ring 8 is below a predetermined threshold. In this embodiment, the retaining member and the locking ring 8 (preferably each flexible leg 88) comprise only one second stop 811, instead of two. The first point 810 and the second point 811 may be offset from each other in the circumferential direction (i.e., not facing each other in the axial direction). It is conceivable that the flexible leg 88 may have two opposite fixed ends 880, 881, instead of one fixed proximal end 880 and one free distal end 881. In addition, the holder 6 comprises two protrusions 66, instead of one. The two protrusions 66 of the retaining member 6 form a first point 660 and a second point 661, which can protrude from the outer surface of the centering leg 65. Figure 8B As shown, the first dot 660 is arranged on one of the two centering legs 65, while the second dot 661 is arranged on the other of the two diametrically opposite centering legs 65. The first dot 660 of the retainer 6 is configured to abut proximally on the first dot 810 of the locking ring 8 for preventing distal movement of the locking ring 8 (and thus preventing removal of the locking ring 8 from the retainer 6). The second dot 661 of the retainer 6 is configured to abut distally on the second dot 811 of the locking ring 8 for preventing accidental proximal movement of the locking ring 8 (and thus preventing accidental activation of the device). Preferably, when the locking ring 8 is in the locked position, the second dot 661 of the retainer 6 abuts against the second dot 811 of the locking ring 8. Thus, the user gets feedback that the injection process is about to start. This also helps to prevent the automatic injection device 1 from being activated during a drop test.

[0090] Figures 9A-9CA maintenance member of an automatic injection device 1 according to another embodiment is shown. The maintenance member comprises: a first blocking feature 660, 810 for blocking the axial movement of the locking ring 8 in the distal direction; and a second blocking feature 661, 811 for blocking the axial movement of the locking ring 8 in the proximal direction when the proximal force applied to the locking ring 8 is below a predetermined threshold. The locking ring 8 has a first dot 810 and a second dot 811, which are arranged in each of the axial grooves 80. That is, the first dot 810 and the second dot 811 are configured to engage with the blocking leg 70 of the retainer 6, and more specifically, with the outward radial protrusion 75 of the blocking leg 70. The blocking leg 70 of the retainer 6 in fact has a first stop 660 which may be orthogonal to the longitudinal axis A, and a second stop 661 which may form an inclined surface at the distal end of the blocking leg 70 so that once the thrust exerted by the needle cover 40 on the locking ring 8 exceeds a predetermined threshold, the second stop 661 allows the locking ring 8 to move axially. In the locked position of the locking ring 8, the first stop 660 abuts against the first point 810 (thereby preventing disassembly) and the second stop 661 abuts against the second point 811 (thereby preventing accidental activation). The first stop 660 and the second stop 661 of the retainer 6 are arranged here on the blocking leg 70 so that the centering leg 65 of the retainer 6 can have a smooth outer surface without any protrusions. The inclined surface formed by the second stop 661 makes it possible to increase the resistance to the drop test, since any movement of the locking ring 8 in the proximal direction causes the blocking legs 70 to deform inwardly against the action of the injection spring 30, which is compressed and thus prevents accidental activation of the device.

[0091] like Fig. 9B As shown, the locking ring 8 here has no flexible legs 88. Instead, the locking ring 8 has two enlarged centering surfaces 87 extending between the two axial grooves 80. The first point 810 and the second point 811 may be offset from each other in the circumferential direction; they are not axially aligned.

[0092] like Fig. 9C As shown, the outward radial protrusion 75 may include an axial slit 750 for improving the flexibility of the blocking leg 70. Thus, the outward radial protrusion 75 is divided into two parallel parts; the first stop 660 may be located on one of the two parts, and the second stop 661 may be located on the other of the two parts. It should also be noted that the width w of the blocking leg 70 may decrease towards its distal end. This may also be applicable to other embodiments of the automatic injection device 1 to improve the flexibility of the blocking leg 70.

[0093] FIG. 10A to FIG. 10C shows a maintenance member of an automatic injection device 1 according to another embodiment. The maintenance member comprises: a first blocking feature 660, 810 for blocking the axial movement of the locking ring 8 in the distal direction; and a second blocking feature 661, 811 for blocking the axial movement of the locking ring 8 in the proximal direction when the proximal force applied to the locking ring 8 is below a predetermined threshold. Here, the maintenance member of the locking ring 8 comprises: a proximal end of the locking ring 8, the proximal end forming a second point 811 for preventing the proximal movement of the locking ring 8 (and thus preventing unintentional activation); and a retainer 6 having a second stop 661 arranged on a resilient arm 662. The proximal end (second point 811) of the locking ring 8 can be configured to abut against the second stop 661 of the retainer 6 when the locking ring 8 is in the locked position, so as to provide feedback to the user that the automatic injection device 1 is about to be activated and limit the risk of accidental activation during the drop test.

[0094] like Figures 10A-10B As shown, the elastic arm 662 is arranged on the centering leg 65 and can be complementary in shape to the axial groove 883 of the locking ring 8. The elastic arm 662 is configured to deform radially inward to allow the locking ring 8 to move toward the unlocked position under the pressure applied by the needle cover 40. To this end, the arm 662 is separated from the sleeve by a radial gap 663. The arm 662 can have two opposite ends fixed to the sleeve 60, so that the radial gap 663 forms a closed loop. Figures 10A-10B As shown, the centering leg 65 of the retaining member 6 may also include an axial rib 664 located distally of the elastic arm 662, and the axial rib 664 is configured to complementarily engage with two diametrically opposite axial grooves 883 of the locking ring 8. The bottom of the axial groove 883 thus forms the centering surface 87 of the locking ring 8. The axial groove 80 of the locking ring 8 may have a radial protrusion forming a first point 810 of the locking ring 8. Figures 9A-9C In a manner similar to the embodiment shown in , the first point 810 of the locking ring 8 is configured to abut distally against the first stop 660 defined by the outward radial protrusion 75 of the blocking leg 70 (thus preventing disassembly).

[0095] The operation of the automatic injection device 1 is as follows.

[0096] Before the automatic injection device 1 is activated, the needle cover 40 is in the first extended position, the plunger rod 20 is in its initial position, the injection spring 30 is in its compressed state, the locking ring 8 is in the locked position, and the blocking leg 70 is in its blocking (resting) position. Therefore, the inward radial protrusion 72 of the blocking leg 70 prevents the plunger rod 20 from moving in the distal direction ( Figure 5A , 5B).

[0097] The user first withdraws the cap 2 from the bottom body 12. This withdrawal requires the removal of the needle shield 102. During the cap removal process, the fixing ring 4 can abut against the proximal shoulder 53 of the cam 50 to prevent the medical container 100 from moving distally.

[0098] The user then places the automatic injection device 1 against the injection site. The distal end 42 of the needle cover 40 is against the injection site. As the user presses the automatic injection device 1 against the injection site, the needle cover 40 moves from the first extended position to the retracted position. This movement of the needle cover 40 in the proximal direction causes the tab 41 of the needle cover 40 to slide against the upper slope 511 of the inclined portion 510 of the first slot 51 of the cam 50. This causes the cam 50 to rotate so that the fixing ring 4 now axially faces the lower slope 520 of the second slot 52 and causes the tab 41 to move at the proximal end 513 of the axial portion 512 of the first slot 51 of the cam 50. The proximal movement of the needle cover 40 toward the retracted position also causes the push surface 44 of the needle cover 40 to abut against the locking ring 8 and thus pushes the locking ring 8 in the proximal direction toward the unlocked position ( Fig. 6A ).

[0099] Therefore, the radially outward projection of the blocking leg 70 is located outside the axial groove 80 of the locking ring 8. Now, since the lateral blocking surface 82 of the locking ring 8 has been axially moved away, the blocking leg 70 is free to deflect radially outward. Since the injection spring 30 applies a distal force on the plunger rod 20, and due to the contact between the plunger rod 20 and the axial stop 71 of the blocking leg 70, the blocking leg 70 is deflected outwardly. The axial stop 71 moves away from the distal abutment surface 22 of the plunger rod 20, and the distal abutment surface of the plunger rod can be moved to the injection end position under the action of the injection spring 30. The plunger rod 20 connected with the stopper 105 first pushes the medical container 100 so that the injection needle reaches the injection site, and then pushes the stopper 105 in the barrel 101 to discharge the medical product. When the stopper 105 finally abuts on the distal end 106 of the reservoir defined by the barrel 101, the injection is completed. An indicator (eg, a visual, tactile, or audible indicator) may inform the user that the injection is complete.

[0100] Then, the user moves the automatic injection device 1 away from the injection site. The needle cover 40 slides in the axial portion 512 of the cam 50 and moves from the retracted position to the second extended (safety) position under the action of the safety spring 3. The locking mechanism can lock the needle cover 40 in the safety position to prevent needle stick injuries.

[0101] Figures 11A-11I An automatic injection device 1 according to another embodiment is shown. Features similar to those of other embodiments are indicated by the same reference numerals. Instead of being located at the distal end of the retaining member 6, the locking ring 8 is here arranged at the proximal end of the retaining member 6. In addition, the retaining member 6 here provides support for the proximal end of the injection spring 30. Fig.11D As shown, the centering leg 65 of the retaining member 6 defines a distal shoulder 650 which serves as a support for the proximal end 32 of the injection spring 30, see Fig. 11C , 11D The automatic injection device 1 also defines a space 160 below its proximal end 16 to allow the locking ring 8 to move to an unlocked position. In the unlocked position, the locking ring 8 can abut against the proximal end 16, more specifically, against the top cap 5 forming the proximal end 16 of the automatic injection device 1.

[0102] The retaining member comprises: a first blocking feature 660, 810 for blocking the axial movement of the locking ring 8 in the distal direction; and a second blocking feature 661, 811 for blocking the axial movement of the locking ring 8 in the proximal direction when the proximal force applied to the locking ring 8 is below a predetermined threshold. The retaining member comprises a first point 810 formed by a distal shoulder 892 of the locking ring 8 abutting against a first stop 660 formed by the proximal end of the connecting piece 17. In addition, the retaining member comprises a second point 811 formed by a radial protrusion in the axial groove 80 of the locking ring 8 for abutting against a second stop 661, which forms a ramp surface at the distal end of the blocking leg 70 and more specifically at the distal end of the outward radial protrusion 75.

[0103] refer to FIG. 11A to FIG. 11B , the locking ring 8 is in the locked position. The proximal end 63 of the tubular sleeve is open and forms a blocking leg 70. The blocking leg 70 can be in the blocking position (which is the rest position, Fig.11A ) and a release position (which is a deformed position) in which the axial stops 71 of the blocking legs 70 axially abut against the distal abutment surface 22 of the plunger rod 20, and in which the blocking legs 70 are radially deflected outwardly so that their axial stops 71 move away from the path of the plunger rod 20. The movement of the blocking legs 70 from the rest position to the deformed position is due to the injection spring 30 pushing the plunger rod 20 in the distal direction. The axial stops 71 of the blocking legs 70 can be arranged at the proximal side of the inward radial protrusion 72, which is located at the proximal end 77 of the blocking legs 70. The distal end 73 of the blocking legs can be fixed to the sleeve 60. The blocking legs 70 can include lateral blocking surfaces 74, which can be defined by outward radial protrusions 75, for abutting against the locking ring 8, thereby keeping the blocking legs 70 in their rest position.

[0104] refer to Figures 11C-11DThe tubular sleeve 60 may also include one or more axially extending centering legs 65 for providing support for the locking ring 8 so that the locking ring 8 can be centered relative to the central longitudinal axis A and can slide along the sleeve 60. The centering legs 65 here do not include the connection features 66 of the retainer 6, but are provided by the outward radial protrusions 75 and the connector 17, as explained above. The centering legs 65 also include a distal shoulder 650, thereby forming a support for the injection spring 30.

[0105] The connecting member 17 may be in the form of a radial wall extending parallel to the longitudinal axis A. Fig.11H As shown, the connecting member 17 has a lateral surface forming a guide rail 171 for guiding the proximal movement of the locking ring 8. More specifically, the two edges 843 arranged on the locking ring 8 are configured to abut against the guide rail 171 along the circumferential direction for guiding the proximal movement of the locking ring 8.

[0106] like Fig. 11C As shown, the needle cover 40 in the first extended position and the locking ring 8 in the locked position can be axially separated by a predetermined axial gap 90. It is worth noting that the needle cover 40 directly abuts against the locking ring 8, as shown in FIG. Fig.11G shown.

[0107] Fig.11I The locking ring 8 is shown. The locking ring 8 is coupled to the sleeve 60 and can be in a locked position ( Figures 11A-11D ) and an unlocked position located proximal to the locked position ( Figures 11E-11F ), in which the locking ring 8 allows the blocking legs 70 to move to their release positions. The movement of the locking ring 8 from the locked position to the unlocked position is caused by the push surface 44 of the needle cover 40 abutting against the distal abutment surface 83 of the locking ring 8. The distal abutment surface 83 of the locking ring 8 can be arranged at the distal end 840 of one or more (e.g. two diametrically opposite) distally extending legs 845. The distal abutment surface 83 can be the most distal surface of the locking ring 8.

[0108] Still refer to Fig.11I The locking ring 8 includes a tubular wall defining an inner cavity 86 for receiving the retaining member 6. The inner side of the tubular wall may define one or more centering surfaces 87, the shape of which is complementary to the centering legs 65 of the retaining member 6. The tubular wall also defines one or more axial grooves 80, the bottom of which defines the lateral blocking surface 82 of the locking ring 8. Therefore, the shape of the axial groove 80 is designed to receive the outward radial protrusion 75 of the blocking leg 70 and allow the locking ring 8 to translate along the blocking leg 70. Fig.11AAs shown, the proximal portion (tubular wall 86) of the locking ring 8 is separated by the distal shoulder 891, and the distal portion of the locking ring 8 defines a radial space 85 for accommodating the blocking leg 70 deformed outward. Here, the axial length of the distal portion (protective wall 84) of the locking ring 8 can be longer than the axial length of the proximal portion (tubular wall 86) of the locking ring 8. Fig.11I As shown, the distal portion of the locking ring 8 further comprises an axial leg 845 which projects distally from the distal shoulder 892 so as to extend along the path of the needle cover 40 and transmit the axial movement of the needle cover 40 to the locking ring 8 by abutting against the needle cover 40 .

[0109] The locking ring 8 cannot rotate about the longitudinal axis A but can only move in the axial direction. The locking ring 8 also includes a guide member 89, which is in the form of two circumferential walls 842, which define two edges 843 for abutting and sliding on the guide track 171 formed by the lateral surface of the connecting piece 17. The edges 843 of the circumferential wall 842 prevent the locking ring 8 from rotating in the first direction. The opposite edge 841 of the leg 845 also abuts on the connecting piece 17 circumferentially to prevent the locking ring 8 from rotating in the opposite direction. The circumferential wall 842 can extend circumferentially from the leg 845, and it can be shorter than the leg 845 in the axial direction to avoid interfering with other parts of the automatic injection device 1. It should also be noted that the locking ring 8 can include an axial rib 844, which protrudes from the inner surface of the protective wall 84 and is configured to abut on the outer surface of the sleeve 60 and slide. The axial rib 844 provides axial guidance for the locking ring 8 while reinforcing the protective wall 84.

[0110] like Fig.11F As shown, in the unlocked position, the distal shoulder 891 of the locking ring 8 can be axially away from the outward radial protrusion 75 of the retainer 6, so that the inner distal shoulder 892 does not hinder the movement of the blocking leg 70 toward its release (deformed) position. More specifically, in the unlocked position, the distal shoulder 891 is axially away from the proximal stopper 76 of the blocking leg 70. The proximal stopper 76 is configured to abut against the distal shoulder 891 of the locking ring 8 to prevent the locking ring 8 from moving back to the blocking position when the needle cover 40 moves away from the locking ring 8 toward the safety position.

[0111] Figures 11A-11I The automatic injection device 1 may also include some or all of the other compatible features of the above-mentioned embodiments.

[0112] It is easy to understand from the above description that the automatic injection device 1 of the present invention can reduce the steps required to trigger the injection (the user does not need to press a button, and the locking ring 8 automatically slides when the automatic injection device 1 is pressed against the user's skin). Since the needle cover 40 directly abuts against the locking ring 8 and they both move in the axial direction, the force required to activate the automatic injection device 1 is smaller than that in the prior art.

[0113] It should be understood that the present invention is not limited to the embodiments described above and shown in the drawings; on the contrary, those skilled in the art will recognize that many changes and modifications are possible within the scope of the appended claims.

Claims

1. An automatic injection device (1) for automatically injecting a product into an injection site, the automatic injection device (1) comprising: A housing (10) extending along a longitudinal axis A and configured to receive a medical container (100) having a barrel (101) defining a reservoir for containing a medical product, the barrel (101) having a distal end provided with an injection needle and an open proximal end (103) configured to receive a plunger rod (20) for pushing a stopper (105) arranged in the barrel (101); a needle cover (40) coupled to the housing (10) and axially movable relative to the housing between a first extended position, in which the needle cover (40) at least partially shields the injection needle, a retracted position, in which the needle cover (40) is moved proximally relative to the housing (10), and a second extended position, in which the needle cover (40) is moved back in the distal direction to shield the injection needle; a plunger rod (20) which is axially movable within the housing (10) between an initial position and an injection end position distal to the initial position, the plunger rod (20) being configured to push the stopper (105) to discharge the medical product when moving from the initial position to the injection end position, a biasing member for biasing the plunger rod (20) in a distal direction toward the injection end position, a retaining member (6) fixed relative to the housing (10) for maintaining the plunger rod (20) in the initial position against the action of the biasing member, the retaining member (6) comprising an elastic blocking member (7) which is radially deformable between a blocking position and a release position, in which the elastic blocking member (7) axially abuts against a distal abutment surface (22) of the plunger rod (20) for blocking the plunger rod (20) in the initial position, and in which the elastic blocking member (7) is away from the distal abutment surface (22) of the plunger rod (20) to allow the plunger rod (20) to move in the distal direction, A locking ring (8) is arranged on the fixed retaining member (6) and is axially movable relative to the elastic blocking member (7) of the retaining member (6), so that the locking ring (8) can slide along the retaining member (6) between a locked position and an unlocked position without rotating, in which the locking ring (8) radially abuts against a lateral blocking surface (74) of the elastic blocking member (7) to retain the elastic blocking member (7) in the blocking position, and in the unlocked position, the locking ring (8) axially moves away from the lateral blocking surface (74) of the elastic blocking member, and the axial movement of the locking ring (8) from the locked position to the unlocked position is caused by the needle cover (40) moving from the first extended position to the retracted position.

2. Automatic injection device (1) according to the preceding claim, wherein: The needle cover (40) has a push surface (44) configured to abut against a distal abutment surface (83) of the locking ring (8) to move the locking ring (8) into the unlocked position when the needle cover (40) moves toward the retracted position.

3. Automatic injection device (1) according to the preceding claim, wherein: Before using the automatic injection device (1), the pushing surface (44) of the needle cover (40) and the distal abutment surface (83) of the locking ring (8) are axially spaced apart from each other by a distance.

4. An automatic injection device (1) according to any one of the preceding claims, wherein: The blocking position of the elastic blocking member (7) is a rest position.

5. An automatic injection device (1) according to any one of the preceding claims, wherein: The retaining member (6) is an axial sleeve (60) arranged in the housing (10), and the elastic blocking member (7) is an axially extending elastic blocking leg (70) forming the distal end or the proximal end of the axial sleeve (60), and the elastic blocking leg (70) includes: an inward radial protrusion (72), the inward radial protrusion defines an axial stop member (71) for abutting against the distal abutment surface (22) of the plunger rod (20); and a relative outward radial protrusion (75), the relative outward radial protrusion defines the lateral blocking surface (74) for abutting against the locking ring (8).

6. An automatic injection device (1) according to any one of the preceding claims, wherein: The locking ring (8) comprises a proximal portion and a distal portion separated by a distal shoulder (891), and the inner diameter D1 of the distal portion is greater than the inner diameter D2 of the proximal portion.

7. The automatic injection device (1) according to claim 5 and claim 6, wherein: The distal shoulder (891) of the locking ring (8) and the outward radial protrusion (75) of the elastic blocking member (7) of the retaining member (6) are axially distanced from each other when the locking ring (8) is in the unlocked position and the elastic blocking member (7) is in the released position.

8. The automatic injection device (1) according to claim 5 and claim 6 or 7, wherein: The outward radial protrusion (75) of the resilient blocking member (7) includes a proximal stop (76) configured to abut against the distal shoulder (891) of the locking ring (8) to prevent the locking ring (8) from moving back to the blocking position.

9. An automatic injection device (1) according to any one of the preceding claims, wherein: The locking ring (8) comprises one or more axial protective walls (84) defining a radial space (85) for receiving the elastic blocking member (7) in the release position.

10. An automatic injection device (1) according to any one of the preceding claims, wherein: The locking ring (8) defines: an inner cavity (86) for receiving the retaining member (6), the inner cavity (86) defining a centering surface for sliding against the retaining member (6) and guiding the locking ring (8) to move along the longitudinal axis A; and an axial groove (80) defining a lateral blocking surface for blocking the elastic blocking member (7) of the retainer (6) in the blocking position.

11. An automatic injection device (1) according to any one of the preceding claims, wherein: The automatic injection device (1) comprises a retaining member for retaining the locking ring (8) assembled to the retainer (6).

12. Automatic injection device (1) according to the preceding claim, wherein: The maintaining member includes at least: a first blocking feature (660, 810) for blocking the axial movement of the locking ring (8) in the distal direction; and a second blocking feature (661, 811) for blocking the axial movement of the locking ring (8) in the proximal direction when the proximal force applied to the locking ring (8) is lower than a predetermined threshold.

13. An automatic injection device (1) according to any one of the preceding claims when dependent on claim 2, wherein: The distal abutment surface (83) of the locking ring (8) is arranged at the distal end of the locking ring (8), and the push surface (44) of the needle cover (40) is arranged at the proximal end of the needle cover (40).

14. An automatic injection device (1) according to any one of the preceding claims when dependent on claim 2, wherein: The needle cover (40) has a radial tab (41) which engages in a first slot (51) of a rotatable cam (50) and has a proximal surface which at least partially forms the push surface (44) of the needle cover (40).

15. An automatic injection device (1) according to any one of the preceding claims, wherein: The locking ring (8) has a guide member (89) for preventing the locking ring (8) from rotating about the longitudinal axis A.

Images