Detent mechanism

Patent metadata

Field	Value
Publication number	US-9687607-B2
Application number	US-201213983807-A
Country	US
Kind code	B2
Filing date	Feb 16, 2012
Priority date	Feb 18, 2011
Publication date	Jun 27, 2017
Grant date	Jun 27, 2017

Abstract

The invention relates to a detent mechanism for controlling translation between two components in a longitudinal direction (P, D), the detent mechanism comprising at least one clip on one of the components arranged to be in a ramped engagement with a recess in the other one of the components in an initial state in such a manner that translation between the components is constrained and that application of a translative force between the components in one longitudinal direction (P, D) with the clip engaged with the recess deflects the clip out of the recess when a predetermined value of the translative force, at least depending on the resilience of the clip, is overcome so as to allow translation between the components.

First claim

The invention claimed is:

1. An auto-injector for administering a dose of a liquid medicament (M), comprising:
a tubular chassis telescopable in a tubular case,
a carrier subassembly comprising a tubular carrier slidably arranged relative to the chassis inside the case, the carrier adapted to contain a syringe with a hollow injection needle, a drive spring and a plunger for forwarding load of the drive spring to a stopper of the syringe, wherein the syringe is lockable for joint axial translation with the carrier,
a trigger button arranged to advance the carrier in the proximal direction (P),
a detent mechanism for controlling translation of the carrier relative to the chassis, wherein the chassis and the carrier are initially coupled for joint axial translation relative to the case, wherein the detent mechanism is arranged to decouple the chassis from the carrier upon actuation of the trigger button thus allowing the carrier to move relative to the chassis, wherein the detent mechanism is attached to the carrier and the chassis, wherein the detent mechanism comprises at least one clip on one of the chassis and the carrier arranged to be in a ramped engagement with a recess in the other one of the chassis and the carrier in an initial state in such a manner that translation between the chassis and the carrier is constrained and that application of a translative force between the chassis and the carrier in one longitudinal direction (P, D) with the clip engaged with the recess deflects the clip out of the recess when a predetermined value of the translative force, at least depending on the resilience of the clip, is overcome so as to allow translation between the chassis and the carrier.

2. The auto-injector according to claim 1 wherein the detent mechanism comprises a second clip arranged as a resilient beam on the carrier extending in the distal direction (D) with a third beam head for abutting the chassis for preventing translation of the carrier in the distal direction (D) from an initial position, wherein the third beam head exhibits a proximal ramp for inwardly deflecting the second clip allowing assembly of the carrier into the chassis in the proximal direction (P) before the syringe is inserted into the carrier, wherein the second clip is arranged to be inwardly supported by the inserted syringe so as to prevent inward deflection of the second clip.

3. The auto-injector according to claim 1 , wherein:
a control spring arranged around the carrier,
a needle insertion control collar for coupling a proximal end of the control spring to either the carrier for advancing it for needle insertion or to the chassis for needle retraction depending on the relative axial position of the carrier and the chassis,
a plunger release arm arranged for releasing the plunger for injection when the carrier has at least almost reached an injection depth during needle insertion,
a syringe retraction control collar arranged for coupling a distal end of the control spring to either the carrier for needle retraction or to the case otherwise,
wherein the needle insertion control collar is allowed to switch the proximal end of the control spring to the carrier for needle insertion when the chassis is decoupled from the carrier by the detent mechanism upon actuation of the trigger button.

4. The auto-injector according to claim 3 , wherein the needle insertion control collar comprises a first collar biased by the control spring in a proximal direction (P), wherein at least one resilient beam is proximally arranged on the first collar, wherein respective recesses are arranged in the carrier and case, wherein a transversal extension of a head of the at least one resilient beam is wider than a gap between the carrier and the chassis causing the head of the at least one resilient beam to abut a distal face on the recess in the chassis while being prevented from deflecting in an inward direction (I) by the carrier or to abut a distal face on the recess in the carrier while being prevented from deflecting in an outward direction (0) by the chassis thereby forwarding load from the control spring to the carrier, wherein the at least one resilient beam is arranged to be switched between the chassis and the carrier by ramped engagement of the head to the distal faces under load of the control spring depending on the relative longitudinal position between the chassis and the carrier.

5. The auto-injector according to claim 3 , wherein the plunger release arm comprises at least one resilient arm on the carrier arranged to be in a ramped engagement to the plunger so as to disengage them under load of the drive spring, wherein a peg protrudes from a distal end face of the trigger button in the proximal direction (P) in a manner to support the at least one resilient arm preventing disengagement of the carrier from the plunger and thus release of the drive spring when the carrier is in a distal position, wherein the trigger button is arranged to remain in position relative to the case when the carrier is translated for advancing the needle so as to pull the at least one resilient arm away from the peg thus allowing deflection of the at least one resilient arm due to the ramped engagement under load of the drive spring for disengaging the plunger from the carrier and releasing the drive spring for drug delivery when the carrier has reached a predefined position during needle advancement.

6. The auto-injector according to claim 2 , wherein a rib for preventing deflection of the resilient beam is arranged on the case so as to lock the detent mechanism prior to being translated in the proximal direction (P) relative to the chassis, and so as to unlock the detent mechanism when the case is translated into an advanced position in the proximal direction (P).

7. The auto-injector according to claim 2 , wherein the distally arranged trigger button is at least initially coupled to the carrier, wherein the case is arranged to abut the trigger button in an initial state preventing depression of the trigger button, wherein on translation of the case into an advanced position the trigger button remains coupled to the carrier thus emerging from the case so as to allow depression for starting an injection cycle.

8. The auto-injector according to claim 3 , wherein the syringe retraction control collar comprises a second collar bearing against the distal end of the control spring and having a resilient proximal beam with a second beam head having an inward boss, wherein the second beam head is arranged to be in a ramped engagement with a second case detent in the case in a manner ramping the second beam head in the inward direction (I) under load of the control spring in the distal direction (D), wherein the inward boss is arranged to inwardly abut the carrier for preventing inward deflection of the second beam head and keep the second collar locked to the case, wherein a third recess is arranged in the carrier for allowing the inward boss to be inwardly deflected on translation of the case in the distal direction (D) relative to the carrier.

9. The auto-injector according to claim 3 , wherein the trigger button is arranged distally, wherein the case is arranged as a wrap-over sleeve trigger having a closed distal end face covering the trigger button, wherein in an initial state a clearance is provided between the distal end face of the sleeve trigger and the trigger button allowing for some travel of the sleeve trigger against the bias of the control spring in the proximal direction (P) in a first phase before abutting the trigger button.

10. The auto-injector according to claim 2 , wherein a releasable noise component comprises an elongate portion and an end plate, the releasable no

Assignees

• Brereton Simon Francis
• Kemp Thomas
• Burnell Rosie
• Ekman Matthew
• Sanofi Aventis Deutschland

Inventors

• Brereton Simon Francis
• Kemp Thomas
• Burnell Rosie
• Ekman Matthew

Classifications

• A61M5/46

  having means for controlling depth of insertion · CPC title

• A61M5/326

  Fully automatic sleeve extension, i.e. in which triggering of the sleeve does not require a deliberate action by the user · CPC title

• A61M2205/581

  by audible feedback · CPC title

• A61M2205/582

  by tactile feedback · CPC title

• Y10T403/32475

  having detent · CPC title