Autoinjector
A detent mechanism for controlling translation between two components in a longitudinal direction includes a resilient beam on one of the components and a rhomboid ramp member on the other component. The resilient beam is essentially straight when relaxed and has a first beam head and is arranged to interact in a ramped engagement with respectively one of two ramps. Each ramp is on one longitudinal side of the rhomboid ramp member such that application of a translative force between the components in one longitudinal direction with the first beam head engaged to one of the ramps in a first state deflects the resilient beam in one transversal direction and such that application of a translative force between the components in the other longitudinal direction with the first beam head engaged to the other one of the ramps deflects the resilient beam in the other transversal direction.
1 . An auto-injector, comprising:
a case adapted to receive a syringe with a needle, wherein the syringe has a container body and a stopper movably retained in the container body, and, in a state of the auto-injector as delivered, the needle is covered by a protective needle sheath;
a plunger arranged to move in a proximal direction relative to the syringe for dispensing a medicament from the syringe when the syringe is disposed in the case;
a plunger release mechanism actuatable to release the plunger to allow a proximal movement of the plunger relative to the syringe, wherein the plunger has a ramp engagement portion which, before the plunger is released, engages a ramp arranged within the case;
a drive spring configured to drive the plunger for dispensing the medicament from the syringe, wherein there is a gap between the stopper and the plunger before the plunger is released, the gap is closed when the plunger is enabled to drive the stopper proximally relative to the container body, and the drive spring is configured to bias the plunger proximally to move the ramp engagement portion of the plunger when the ramp engagement portion is in engagement with the ramp to rotate the plunger for releasing the plunger;
a blocking feature arranged to block a rotation of the plunger before the plunger is released, wherein the blocking feature releasably engages the plunger and is rotationally locked relative to the case; and
a cap operatively coupled to the protective needle sheath via a barb to remove the protective needle sheath together with the cap,
wherein the auto-injector is configured so as to rotate the plunger relative to the case to release the plunger for the proximal movement relative to the syringe.
2 . The auto-injector of claim 1 , wherein the auto-injector further comprises a chassis, wherein the case has a closed distal end and is configured to be moved proximally relative to the chassis to release the plunger.
3 . The auto-injector of claim 2 , wherein the chassis is configured to be pressed against an injection site at a body of a patient, and the chassis protrudes from the case in the state of the auto-injector as delivered.
4 . The auto-injector of claim 1 , wherein the blocking feature is axially movable relative to the case, and the blocking feature and the plunger are configured to be displaced relative to each other to release the engagement between the plunger and the blocking feature for releasing the plunger for the proximal movement relative to the syringe.
5 . The auto-injector of claim 1 , wherein the syringe is arranged within a syringe carrier, wherein the syringe carrier is arranged within the case.
6 . The auto-injector of claim 1 , wherein the cap is removably attached to the case at a proximal end of the case, and the protective needle sheath is attached to the needle.
7 . The auto-injector of claim 6 , wherein the cap and the case are operatively coupled by a profiled interface configured to allow rotation of the cap relative to the case when the cap is attached to the case, such that the cap is removed from the case when the cap is rotated relative to the case.
8 . The auto-injector of claim 7 , wherein the barb is connected to the cap in a manner allowing the barb and the cap to rotate independently so as to limit torque on the protective needle sheath when the cap is rotated.
9 . The auto-injector of claim 1 , wherein the auto-injector comprises a noise release mechanism configured to generate noise to indicate an end of a dose delivery operation such that during the dose delivery operation, a portion of the plunger engages at least one deflectable clip disposed within the case and the noise is generated when the portion has passed the at least one deflectable clip.
10 . The auto-injector of claim 1 , wherein the auto-injector is configured to deliver only one dose of the medicament.
11 . An auto-injector comprising:
a case adapted to receive a syringe comprising a needle with a protective needle sheath covering the needle of the syringe;
a plunger configured to move in a proximal direction relative to the syringe for dispensing a medicament from the syringe when the syringe is disposed in the case;
a plunger release mechanism actuatable to release the plunger to allow the plunger to move in the proximal direction relative to the syringe;
a blocking feature configured to releasably engage an outward protrusion of the plunger to limit a rotation of the plunger relative to the case while the plunger is rotationally biased towards the blocking feature by a ramp; and
a cap configured to be operatively coupled to the protective needle sheath via a barb such that removal of the cap from the case removes the protective needle sheath from the syringe,
wherein the auto-injector is configured such that a relative axial movement between the plunger and the blocking feature disengages the outward protrusion of the plunger from the blocking feature to allow the plunger to rotate relative to the case while the plunger is rotationally biased by the ramp to release the plunger such that the plunger moves in the proximal direction relative to the syringe to dispense the medicament from the syringe.
12 . The auto-injector of claim 11 , wherein the syringe has a container body and a stopper movably retained in the container body, there is a gap between the stopper and the plunger before the plunger is released, and the gap is closed when the plunger drives the stopper proximally relative to the container body.
13 . The auto-injector of claim 11 , further comprising a drive spring configured to drive the plunger for dispensing the medicament from the syringe, wherein the drive spring is configured to bias the plunger proximally to move the outward protrusion of the plunger, when the outward protrusion is in engagement with the ramp, to rotate the plunger for releasing the plunger.
14 . The auto-injector of claim 11 , wherein the blocking feature is arranged to limit the rotation of the plunger before the plunger is released, and the blocking feature is rotationally locked relative to the case.
15 . The auto-injector of claim 11 , wherein the cap and the case are operatively coupled by a profiled interface configured to allow rotation of the cap relative to the case when the cap is attached to the case such that the cap is removed from the case when the cap is rotated relative to the case, and the barb is connected to the cap in a manner allowing the barb and the cap to rotate independently so as to limit torque on the protective needle sheath when the cap is rotated.