Clutch Mechanism

• US 20130112521A1
• Filed: 02/16/2011
• Published: 05/09/2013
• Est. Priority Date: 02/18/2010
• Status: Active Grant

• Current Assignee: Sanofi-Aventis Deutschland GmbH (Sanofi )
• Original Assignee: Sanofi-Aventis Deutschland GmbH (Sanofi )
• Inventors: Ekman, Matthew, Barrow-Williams, Timothy Donald, Hourmand, Yannick
• Granted Patent: US 9,572,937 B2
• Time in Patent Office: Days
• US Class Current: 192/69.8
• CPC Class Codes: A61M 2005/206 With automatic needle insertion
• CPC Class Codes: A61M 2005/208 Release is possible only when device is pushed against the skin, e.g. using a trigger which is blocked or inactive when the device is not pushed against the skin
• CPC Class Codes: A61M 2005/3247 Means to impede repositioning of protection sleeve from needle covering to needle uncovering position
• CPC Class Codes: A61M 2205/581 by audible feedback
• CPC Class Codes: A61M 5/20 Automatic syringes, e.g. with automatically actuated piston rod, with automatic needle injection, filling automatically A61M5/142 , A61M5/46 take precedence; hypodermic projectiles F42B12/54
• CPC Class Codes: A61M 5/326 Fully automatic sleeve extension, i.e. in which triggering of the sleeve does not require a deliberate action by the user
• CPC Class Codes: A61M 5/46 having means for controlling depth of insertion

Abstract

The invention relates to a clutch mechanism for the transmission of a rotary movement from a gear arrangement comprising a first gear member and a second gear member. The first gear member is rotatable about a longitudinal axis but axially fixed wherein the first gear member, upon rotation, is arranged for translatively moving a second gear member which is prevented from rotating. The clutch mechanism comprises a circumferential shoulder arranged at the second gear member and at least one or a number of resilient clutch fingers with respective inclined inner surfaces arranged at the first gear member, the shoulder arranged for increasingly pressing against the inclined surfaces thereby flexing the clutch fingers outward when the shoulder reaches the clutch fingers in the course of its translation. The clutch mechanism further comprises tube arranged around the clutch fingers, the tube having a number of internal longitudinal splines for engaging the flexed-out clutch fingers.

Claims

1-15. -15. (canceled)

16. Clutch mechanism for transmission of a rotary movement from a gear arrangement comprising a first gear member and a second gear member, the first gear member rotatable about a longitudinal axis but axially fixed wherein the first gear member, upon rotation, is arranged for translatively moving a second gear member which is prevented from rotating, wherein the clutch mechanism comprises a circumferential shoulder arranged at the second gear member and at least one resilient clutch finger with a respective inclined inner surface arranged at the first gear member, the shoulder arranged for increasingly pressing against the inclined surface thereby flexing the clutch finger outward when the shoulder reaches the clutch finger in the course of its translation, wherein the clutch mechanism further comprises a tube arranged around the clutch finger, the tube having a number of internal longitudinal splines for engaging the flexed-out clutch finger.

17. Clutch mechanism according to claim 16, characterized in that the internal longitudinal splines are arranged in a manner to form a ratchet when engaged with the clutch fingers.

18. Clutch mechanism according to claim 16, characterized in that each clutch finger has a respective external tooth arranged for engaging the longitudinal splines.

19. Clutch mechanism according to claim 16, characterized in that the second gear member is a piston rod having an external lead screw thread, wherein the first gear member is a lead nut engaged with the external lead screw thread.

20. Clutch mechanism according to claim 19, characterized in that the lead nut is provided with an internal lead screw thread or with at least one pin or with at least one ball bearing for engaging the external lead screw thread.

21. Clutch mechanism according to claim 19, characterized in that the external lead screw thread has a variable pitch.

22. Auto-injector for administering a dose of a liquid medicament (M) comprising a clutch mechanism according to claim 16, the auto-injector further comprising:

an elongate housing arranged to contain a syringe with a hollow needle and a bung for sealing the syringe and displacing the medicament (M), the elongate housing having a distal end (D) and a proximal end (P) with an orifice intended to be applied against an injection site, wherein the syringe is slidably arranged with respect to the housing,

a torsion spring capable of, upon activation, pushing the needle from a covered position inside the housing into an advanced position through the orifice and past the proximal end (P) as well as operating the syringe to supply the dose of medicament (M), the torsion spring arranged around the tube,

activating means arranged to lock the torsion spring in a pressurized state prior to manual operation and capable of, upon manual operation, releasing the torsion spring for injection,

wherein the torsion spring is grounded at one end in the housing and at the other end in the first gear member, wherein the second gear member is a piston rod coupled to the bung in order to push it towards the proximal end (P), the piston rod having an axial bore for slidably arranging the piston rod on a shaft attached to the housing, the axial bore and the shaft having corresponding non-circular profiles, wherein the first gear member is engaged with the activating means prior to manual operation in a manner to prevent rotation and disengaged from the activating means upon manual operation, wherein an essentially tube-shaped needle shroud is arranged around the syringe in the housing, the needle shroud slideable between at least a drawn back position with the needle shroud almost hidden inside the housing and an advanced position with the needle shroud protruding from the proximal end (P) and covering the hollow needle in its advanced position, wherein the needle shroud is biased by a second spring means towards the advanced position and locked in the drawn back position by a locking means which is releasable by rotary movement transmitted by the clutch mechanism which is engaged by the second gear member shortly before the second gear member is fully advanced during an injection stroke.

23. Auto-injector according to claim 22, characterized in that the locking means has the shape of a bayonet fit between the needle shroud and an outer rear tube arranged around the torsion spring and attached to the tube at their distal ends, wherein the needle shroud is guided in the housing in a manner to prevent relative rotation, wherein the bayonet fit comprises a bayonet pin arranged at one of the outer rear tube or the needle shroud and a pin track arranged in the other one of the outer rear tube or the needle shroud.

24. Auto-injector according to claim 22, characterized in that a locking mechanism is provided for locking the needle shroud in its advanced position.

25. Auto-injector according to claim 22, characterized in that an interlock mechanism is arranged for locking the activating means and preventing it from being manually operated, wherein the interlock mechanism is coupled to the needle shroud, wherein the interlock mechanism is releasable by pushing the needle shroud a small distance into the housing from the needle shroud'"'"'s retracted position.

26. Auto-injector according to claim 22, characterized in that the activating means is a trigger button, laterally arranged at the housing and operable by being pressed transversally with respect to the longitudinal axis.

27. Auto-injector according to claim 26, characterized in that the trigger button has a locking pin engageable with at least one dog tooth provided at the first gear member for preventing rotation thereof in order to lock the spring means in its pressurized state.

28. Auto-injector according to claim 25, characterized in that the interlock mechanism comprises respective catches provided at the needle shroud and the trigger button.

29. Auto-injector according to claim 22, characterized in that the syringe is arranged in a syringe carrier and supported by the syringe carrier at a proximal end, wherein the syringe carrier is slidably arranged in the needle shroud and wherein an abutment is provided in the needle shroud defining a maximum forward position of the syringe carrier.

30. Auto-injector according to claim 22, characterized in that at least one viewing window for inspecting the syringe is provided in the housing.